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Anatomy_Gray. Fig. 4.98 This oblique radiograph demonstrates contrast passing through a colonic stent that has been placed to relieve bowel obstruction prior to surgery. Fig. 4.99 This double-contrast barium enema demonstrates numerous small outpouchings throughout the distal large bowel predominantly within the descending colon and the sigmoid colon. These small outpouchings are diverticula and in most instances remain quiescent. Fig. 4.100 Axial CT of inflamed sigmoid colon in patient with diverticulitis. Fig. 4.101 Position of the liver in the abdomen. Fig. 4.102 Surfaces of the liver and recesses associated with the liver. Fig. 4.103 Diaphragmatic surface of the liver. Fig. 4.104 Visceral surface of the liver. A. Illustration. B. Abdominal computed tomogram, with contrast, in the axial plane.


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Anatomy_Gray. Fig. 4.103 Diaphragmatic surface of the liver. Fig. 4.104 Visceral surface of the liver. A. Illustration. B. Abdominal computed tomogram, with contrast, in the axial plane. Left lobe of liverLeft lobe of liverRight lobeof liverCaudate lobeRight lobe of liverQuadrate lobeQuadrate lobeGallbladderAnteriorPosteriorFundusBodyNeckCystic ductPorta hepatisPortal veinFissure for ligamentum teresFissure for ligamentumvenosumHepatic artery properHepatic ductsBile ductABGallbladderPortal veinInferior vena cavaStomachNeck of pancreasSpleenLeft kidneyAortaRight crusLeft crus Fig. 4.105 Posterior view of the bare area of the liver and associated ligaments. Inferior vena cavaSuprarenal impressionLeft lobe of liverRight lobe of liver Renal impressionCaudate lobeGastric impressionEsophageal impressionColic impressionQuadrate lobeFalciform ligamentGallbladderPorta hepatisAnterior coronary ligamentPosterior coronary ligamentRight triangularligamentLeft triangular ligamentBare areaFundusBodyNeck


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Anatomy_Gray. Fig. 4.106 Arterial supply to the liver and gallbladder. A. Schematic. B. Laparoscopic surgical view of cystic duct and cystic artery. Fig. 4.107 Pancreas. Fig. 4.108 Abdominal images. A. Abdominal computed tomogram, with contrast, in the axial plane. B. Abdominal ultrasound scan. GallbladderPancreasPortal veinSplenic veinStomachLeft colonic flexureSpleenLeft kidneyAortaInferior vena cavaRight lobe of liverRight crusALeft crus Left lobe of liverBSplenic arterySuperior mesenteric arteryPancreasLeft renal veinAortaInferior vena cavaVertebra Fig. 4.109 Pancreatic duct system. Fig. 4.110 Arterial supply to the pancreas. Posterior view. Fig. 4.111 Bile drainage. A. Duct system for passage of bile. B. Percutaneous transhepatic cholangiogram demonstrating the bile duct system. GallbladderCystic ductBile ductBile ductRight hepatic ductLeft hepatic ductCommon hepatic ductCystic ductNeedleCommonhepatic ductMain pancreatic ductDescending part of duodenumDescending part of duodenumAB


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Anatomy_Gray. Fig. 4.112 Spleen. Fig. 4.113 Splenic ligaments and related vasculature. Fig. 4.114 Surfaces and hilum of the spleen. Fig. 4.115 Arterial supply to the spleen. Fig. 4.116 Division of the liver into segments based upon the distributions of the bile ducts and hepatic vessels (Couinaud’s segments). Fig. 4.117 Gallbladder containing multiple stones. Ultrasound scan. Fig. 4.118 Magnetic resonance cholangiopancreatography (MRCP) in the coronal plane. Fig. 4.119 Endoscopic retrograde cholangiopancreatography (ERCP) of biliary system. Endoscope with side-viewing optic mechanismStent in common bile duct Fig. 4.120 Coronal CT of the abdomen containing a massively enlarged spleen (splenomegaly). Fig. 4.121 Anterior branches of the abdominal aorta. Fig. 4.122 Divisions of the gastrointestinal tract into foregut, midgut, and hindgut, summarizing the primary arterial supply to each segment.


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Anatomy_Gray. Fig. 4.121 Anterior branches of the abdominal aorta. Fig. 4.122 Divisions of the gastrointestinal tract into foregut, midgut, and hindgut, summarizing the primary arterial supply to each segment. Fig. 4.123 Celiac trunk. A. Distribution of the celiac trunk. B. Digital subtraction angiography of the celiac trunk and its branches. Fig. 4.124 Arterial supply to the pancreas. Fig. 4.125 Distribution of the common hepatic artery. Fig. 4.126 Initial branching and relationships of the superior mesenteric artery. Fig. 4.127 Superior mesenteric artery. A. Distribution of the superior mesenteric artery. B. Digital subtraction angiography of the superior mesenteric artery and its branches. Fig. 4.128 Inferior mesenteric artery. A. Distribution of the inferior mesenteric artery. B. Digital subtraction angiography of the inferior mesenteric artery and its branches. Fig. 4.129 Arterial supply to the abdominal parts of the gastrointestinal system and to the spleen.


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Anatomy_Gray. Fig. 4.129 Arterial supply to the abdominal parts of the gastrointestinal system and to the spleen. Fig. 4.130 Enlarged marginal artery connecting the superior and inferior mesenteric arteries. Digital subtraction angiogram. Fig. 4.131 Portal vein. Fig. 4.132 Venous drainage of the abdominal portion of the gastrointestinal tract. Fig. 4.133 Portosystemic anastomoses. LiverSpleenSplenic veinSuperior mesenteric veinSuperior rectal veinInferior rectal veinsInferior vena cavaInferior mesenteric veinLeft gastric veinPortal veinRectumStomachTributaries to azygos veinSuperficial veinson abdominal wallExternal iliac veinInternal iliac veinCommon iliac veinPara-umbilical veinsthat accompany theligamentum teres Fig. 4.134 Lymphatic drainage of the abdominal portion of the gastrointestinal tract. Fig. 4.135 Sympathetic trunks. Fig. 4.136 Splanchnic nerves. Fig. 4.137 Abdominal prevertebral plexus and ganglia.


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Anatomy_Gray. Fig. 4.135 Sympathetic trunks. Fig. 4.136 Splanchnic nerves. Fig. 4.137 Abdominal prevertebral plexus and ganglia. Fig. 4.138 Parasympathetic innervation of the abdominal portion of the gastrointestinal tract. Fig. 4.139 The enteric system. Fig. 4.140 Posterior abdominal region. Fig. 4.141 Osteology of the posterior abdominal wall. Fig. 4.142 Muscles of the posterior abdominal wall. Fig. 4.143 Diaphragm. Left phrenic nerveRight phrenic nerveInferior phrenicarteryAortaThoracic ductEsophagus with anteriorand posterior vagal trunksLIVLIIILIILISuperior epigastric arteryCentral tendonInferior vena cavaHemi-azygos veinGreater splanchnic nerveLesser splanchnic nerveLeast splanchnic nerveLeft crusSympathetic trunkRight crus Fig. 4.144 Crura of the diaphragm. Fig. 4.145 Right and left domes of the diaphragm. Chest radiograph. Fig. 4.146 Fetal diaphragmatic hernia in utero. T2-weighted MR image. Fetus in coronal plane, mother in sagittal plane.


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Anatomy_Gray. Fig. 4.145 Right and left domes of the diaphragm. Chest radiograph. Fig. 4.146 Fetal diaphragmatic hernia in utero. T2-weighted MR image. Fetus in coronal plane, mother in sagittal plane. Fetal vertebralcolumnFetal abdominalcontents (fluid-filledloops of intestine)in left side ofthoracic cavityFetal headNormal fetal lung development on rightside of thoracic cavityFetal diaphragmdeveloped onright sideMaternal lumbarvertebra Fig. 4.147 Lower esophagus and upper stomach showing a hiatal hernia. Radiograph using barium. Fig. 4.148 Coronal CT of hiatal hernia. Fig. 4.149 Retroperitoneal position of the kidneys in the posterior abdominal region. Inferior vena cavaDiaphragmRight suprarenal glandLeft suprarenal glandRight kidneyLeft kidneyCut edges of peritoneumAbdominal aortaEsophagus Fig. 4.150 Structures related to the anterior surface of each kidney.


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Anatomy_Gray. Fig. 4.150 Structures related to the anterior surface of each kidney. StomachLiverPancreasDescending colonSmall intestineSpleenJejunumRight colic flexureLeft colic flexureDescending part of duodenumRight suprarenal glandLeft suprarenal gland Fig. 4.151 Structures related to the posterior surface of each kidney. Fig. 4.152 Organization of fat and fascia surrounding the kidney. Fig. 4.153 Internal structure of the kidney. Renal arteryRenal veinPyramid in renal medullaRenal sinusMinor calyxRenal cortexRenal papillaRenal columnRenal pelvisMajor calyxUreterHilum of kidney Fig. 4.154 A. Renal vasculature. B. CT image showing long left renal vein crossing the midline. Fig. 4.155 Ureters. Internal iliac arteryExternal iliac arteryCommon iliac arteryGonadal arteriesLeft kidneyLeft renal arteryRight renal arteryRight kidneyAbdominal aortaBladderUreterThird constriction—entrance to bladderSecond constriction—pelvic inletFirst constriction—ureteropelvic junctionUreter


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Anatomy_Gray. Fig. 4.156 Low-dose axial CT of urinary tract (CT KUB) displays stone in left renal pelvis. Fig. 4.157 Tumor in the right kidney growing toward, and possibly invading, the duodenum. Computed tomogram in the axial plane. Fig. 4.158 Tumor in the right kidney spreading into the right renal vein. Computed tomogram in the axial plane. Fig. 4.159 Transitional cell carcinoma in the pelvis of the right kidney. Coronal computed tomogram reconstruction. Fig. 4.160 This radiograph demonstrates a double-J stent (anteroposterior view). The superior aspect of the double-J stent is situated within the renal pelvis. The stent passes through the ureter, describing the path of the ureter, and the tip of the double-J stent is projected over the bladder, which appears as a slightly dense area on the radiograph.


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Anatomy_Gray. Fig. 4.161 Kidney transplant. A. This image demonstrates an MR angiogram of the bifurcation of the aorta. Attaching to the left external iliac artery is the donor artery for a kidney that has been transplanted into the left iliac fossa. B. Abdominal computed tomogram, in the axial plane, showing the transplanted kidney in the left iliac fossa. AAbdominal aortaCommon iliac arteryExternal iliacarteryInternal iliacarteryThe left external iliac arteryhas been used to connectto the donor kidneyTransplant kidneyin the left iliacfossa Fig. 4.162 Coronal view of 3-D urogram using multidetector computed tomography. Fig. 4.163 Arterial supply to the suprarenal glands. Fig. 4.164 Abdominal aorta.


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Anatomy_Gray. Fig. 4.162 Coronal view of 3-D urogram using multidetector computed tomography. Fig. 4.163 Arterial supply to the suprarenal glands. Fig. 4.164 Abdominal aorta. Fig. 4.165 Volume-rendered reconstruction using multidetector computed tomography of patient with an infrarenal abdominal aortic aneurysm before (A) and after (B) endovascular aneurysm repair. Note the image only demonstrates the intraluminal contrast and not the entire vessel. White patches in the aorta represent intramural calcium. Fig. 4.166 Inferior vena cava. Fig. 4.167 Lumbar veins. Fig. 4.168 Abdominal lymphatics. Inferior vena cavaIntestinal trunkRight lumbar trunk with lateral aortic (lumbar) nodesLeft lumbar trunk withlateral aortic (lumbar) nodesExternal iliac nodesExternal iliac nodesInternal iliac nodesCommon iliac nodesCeliac nodesSuperior mesenteric nodesInferior mesenteric nodesCisterna chyliPre-aortic nodes Fig. 4.169 Sympathetic trunks passing through the posterior abdominal region.


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Anatomy_Gray. Fig. 4.169 Sympathetic trunks passing through the posterior abdominal region. Fig. 4.170 Prevertebral plexus and ganglia in the posterior abdominal region. Fig. 4.171 Nerve fibers passing through the abdominal prevertebral plexus and ganglia. Fig. 4.172 Prevertebral ganglia associated with the prevertebral plexus. Fig. 4.173 Lumbar plexus. T12L1L2L3L4To lumbosacral trunkObturator nerveFemoralnerveTo iliacusmuscleLateral cutaneousnerve of thighGenitofemoralnerveIlio-inguinal nerveIliohypogastricnerve Fig. 4.174 Lumbar plexus in the posterior abdominal region. Subcostal nerveIliohypogastric nerveIlio-inguinal nerveLateral cutaneous nerve of thighFemoral nerveGenitofemoral nerveObturator nerveSubcostal nerve (T12)Iliohypogastric nerve (L1)Psoas major muscleIlio-inguinal nerve (L1)Lateral cutaneous nerve of thigh (L2,L3)Femoral nerve (L2 to L4)Genitofemoral nerve (L1,L2)Iliacus muscleObturator nerve (L2 to L4)Lumbosacral trunks(L4,L5)


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Anatomy_Gray. Fig. 4.175 Cutaneous distribution of the nerves from the lumbar plexus. L1T12T12T12T11T11T10T10Ilio-inguinal nerve (L1)Ilio-inguinal nerve (L1)Genitofemoral nerve (L1,L2)Lateral cutaneous nerve of thigh (L2,L3)Obturator nerve (L2 to L4)Cutaneous branch of obturator nerve (L2 to L4)Femoral nerve (L2 to L4)Lateral cutaneous branchof iliohypogastric nerve (L1)Anterior cutaneous branchof iliohypogastric nerve (L1)Femoral branch of genitofemoral nerve (L1,L2)Lateral cutaneous nerve of thigh (L2,L3)Intermediate cutaneous from femoral nerveMedial cutaneous fromfemoral nerveSaphenous nerve from femoral nerve Fig. 4.176 Interior view of the abdominal region of a man. Palpable bony landmarks, the inguinal ligament, and the position of the diaphragm are indicated. Fig. 4.177 Groin. A. In a man. B. In a woman. C. Examination of the superficial inguinal ring and related regions of the inguinal canal in a man.


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Anatomy_Gray. Fig. 4.177 Groin. A. In a man. B. In a woman. C. Examination of the superficial inguinal ring and related regions of the inguinal canal in a man. Deep inguinal ringAponeurosis of external obliqueAponeurosis of external obliqueSuperficial inguinal ringPosition of pubic symphysisABCAnterior superior iliac spineSpermatic cordInguinal ligamentFemoral arteryDeep inguinal ringSuperficial inguinal ringPosition of pubic symphysisAnterior superior iliac spineRound ligament of uterusInguinal ligamentFemoral artery Fig. 4.178 Landmarks used for establishing the positions of lumbar vertebrae are indicated. Anterior view of the abdominal region of a man. End of ninth costal cartilageLower edge of tenthcostal cartilageHighest point on iliac crestLILIILIIILIVLVPubic symphysisTubercle of crest of iliumJugular notchTranspyloric planeSubcostal planeSupracristal planeIntertubercular planeUmbilicus910


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Anatomy_Gray. Fig. 4.179 LI vertebral level and the important viscera associated with this level. Anterior view of the abdominal region of a man. KidneyEnd of ninth costal cartilageLI9Pubic symphysisJugular notchDuodenumTranspyloric planeNeck of pancreasSuperior mesenteric artery Fig. 4.180 Major vessels projected onto the body’s surface. Anterior view of the abdominal region of a man. Upper border of LICeliac trunkAortaLower border of LISuperior mesenteric arteryLIII Inferior mesenteric arteryLIV Bifurcation of aortaLV Joining of common iliacveins to form the inferiorvena cavaLII Approximate originof renal arteryLITXIILIILIIILIVLVPubic symphysisJugular notchTranspyloric planeSubcostal planeSupracristal planeIntertubercular planeUmbilicusInferior vena cava910 Fig. 4.181 Abdominal quadrants and the positions of major viscera. Anterior view of a man. Fig. 4.182 The nine regions of the abdomen. Anterior view of a woman.


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Anatomy_Gray. Fig. 4.181 Abdominal quadrants and the positions of major viscera. Anterior view of a man. Fig. 4.182 The nine regions of the abdomen. Anterior view of a woman. Fig. 4.183 Surface projection of the kidneys and ureters. Posterior view of the abdominal region of a woman. Fig. 4.184 Surface projection of the spleen. Posterior view of a man. eFig. 4.187 Transjugular liver biopsy needle in the right hepatic vein. Radiograph. eFig. 4.188 Subphrenic collection of pus and gas. Computed tomogram in the axial plane. Subphrenic collection of pus and gas eFig. 4.189 Position of a transjugular intrahepatic portosystemic shunt stent. Radiograph. eFig. 4.190 Functioning transjugular intrahepatic portosystemic shunt. Venogram. Fig. 4.185 Tumor in the head of the pancreas. Computed tomogram in the axial plane. eFig. 4.191 A computed tomogram, in the axial plane, of the pelvis demonstrates a loop of sigmoid colon with numerous diverticula and a large abscess in the pelvic cavity.


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Anatomy_Gray. eFig. 4.191 A computed tomogram, in the axial plane, of the pelvis demonstrates a loop of sigmoid colon with numerous diverticula and a large abscess in the pelvic cavity. Fig. 4.186 This postcontrast computed tomogram, in the axial plane, demonstrates two metastases situated within the right lobe of the liver. The left lobe of the liver is clear. The larger of the two metastases is situated to the right of the middle hepatic vein, which lies in the principal plane of the liver dividing the left and right sides of the liver. Table 4.1 Abdominal wall muscles Table 4.2 Posterior abdominal wall muscles Table 4.3 Branches of the abdominal aorta Table 4.4 Lymphatic drainage Table 4.5 Referred pain pathways (visceral afferents) Table 4.6 Branches of the lumbar plexus In the clinic


Anatomy_Gray

Anatomy_Gray. Table 4.3 Branches of the abdominal aorta Table 4.4 Lymphatic drainage Table 4.5 Referred pain pathways (visceral afferents) Table 4.6 Branches of the lumbar plexus In the clinic Access to the abdomen and its contents is usually obtained through incisions in the anterior abdominal wall. Traditionally, incisions have been placed at and around the region of surgical interest. The size of these incisions was usually large to allow good access and optimal visualization of the abdominal cavity. As anesthesia has developed and muscle-relaxing drugs have become widely used, the abdominal incisions have become smaller. Currently, the most commonly used large abdominal incision is a central craniocaudad incision from the xiphoid process to the symphysis pubis, which provides wide access to the whole of the abdominal contents and allows an exploratory procedure to be performed (laparotomy). In the clinic


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Anatomy_Gray. In the clinic Laparoscopic surgery, also known as minimally invasive or keyhole surgery, is performed by operating through a series of small incisions no more than 1 to 2 cm in length. As the incisions are much smaller than those used in traditional abdominal surgery, patients experience less postoperative pain and have shorter recovery times. There is also a favorable cosmetic outcome with smaller scars. Several surgical procedures such as appendectomy, cholecystectomy, and hernia repair, as well as numerous orthopaedic, urological, and gynecological procedures, are now commonly performed laparoscopically.


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Anatomy_Gray. During the operation, a camera known as a laparoscope is used to transmit live, magnified images of the surgical field to a monitor viewed by the surgeon. The camera is inserted into the abdominal cavity through a small incision, called a port-site, usually at the umbilicus. In order to create enough space to operate, the abdominal wall is elevated by inflating the cavity with gas, typically carbon dioxide. Other long, thin surgical instruments are then introduced through additional port-sites, which can be used by the surgeon to operate. The placement of these port-sites is carefully planned to allow optimal access to the surgical field.


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Anatomy_Gray. Laparoscopic surgery has been further enhanced with the use of surgical robots. Using these systems the surgeon moves the surgical instruments indirectly by controlling robotic arms, which are inserted into the operating field through small incisions. Robot-assisted surgery is now routinely used worldwide and has helped overcome some of the limitations of laparoscopy by enhancing the surgeon’s dexterity. The robotic system is precise, provides the surgeon with a 3D view of the surgical field, and allows improved degree of rotation and manipulation of the surgical instruments. Several procedures such as prostatectomy and cholecystectomy can now be performed with this method.


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Anatomy_Gray. Laparoendoscopic single-site surgery, also known as single-port laparoscopy, is the most recent advance in laparoscopic surgery. This method uses a single incision, usually umbilical, to introduce a port with several operating channels and can be performed with or without robotic assistance. Benefits include less postoperative pain, a faster recovery time, and an even better cosmetic result than traditional laparoscopic surgery. In the clinic


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Anatomy_Gray. In the clinic In men, the cremaster muscle and cremasteric fascia form the middle or second covering of the spermatic cord. This muscle and its associated fascia are supplied by the genital branch of the genitofemoral nerve (L1/L2). Contraction of this muscle and the resulting elevation of the testis can be stimulated by a reflex arc. Gently touching the skin at and around the anterior aspect of the superior part of the thigh stimulates the sensory fibers in the ilio-inguinal nerve. These sensory fibers enter the spinal cord at level L1. At this level, the sensory fibers stimulate the motor fibers carried in the genital branch of the genitofemoral nerve, which results in contraction of the cremaster muscle and elevation of the testis.


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Anatomy_Gray. The cremasteric reflex is more active in children, tending to diminish with age. As with many reflexes, it may be absent in certain neurological disorders. Although it can be used for testing spinal cord function at level L1 in men, its clinical use is limited. In the clinic Masses around the groin Around the groin there is a complex confluence of anatomical structures. Careful examination and good anatomical knowledge allow determination of the correct anatomical structure from which the mass arises and therefore the diagnosis. The most common masses in the groin are hernias. The key to groin examination is determining the position of the inguinal ligament. The inguinal ligament passes between the anterior superior iliac spine laterally and the pubic tubercle medially. Inguinal hernias are above the inguinal ligament and are usually more apparent on standing. A visual assessment of the lump is necessary, bearing in mind the anatomical landmarks of the inguinal ligament.


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Anatomy_Gray. In men, it is wise to examine the scrotum to check for a lump. If an abnormal mass is present, an inability to feel its upper edge suggests that it may originate from the inguinal canal and might be a hernia. By placing the hand over the lump and asking the patient to cough, the lump bulges outward. An attempt should be made to reduce the swelling by applying gentle, firm pressure over the lump. If the lump is reducible, the hand should be withdrawn and careful observation will reveal recurrence of the mass. The position of an abnormal mass in the groin relative to the pubic tubercle is very important, as are the presence of increased temperature and pain, which may represent early signs of strangulation or infection. As a general rule: An inguinal hernia appears through the superficial inguinal ring above the pubic tubercle and crest. A femoral hernia (see below) appears through the femoral canal below and lateral to the pubic tubercle.


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Anatomy_Gray. A femoral hernia (see below) appears through the femoral canal below and lateral to the pubic tubercle. A hernia is the protrusion of a viscus, in part or in whole, through a normal or abnormal opening. The viscus usually carries a covering of parietal peritoneum, which forms the lining of the hernial sac. Hernias occur in a variety of regions. The commonest site is the groin of the lower anterior abdominal wall. In some patients, inguinal hernias are present from birth (congenital) and are caused by the persistence of the processus vaginalis and the passage of viscera through the inguinal canal. Acquired hernias occur in older patients and causes include raised intraabdominal pressure (e.g., from repeated coughing associated with lung disease), damage to nerves of the anterior abdominal wall (e.g., from surgical abdominal incisions), and weakening of the walls of the inguinal canal.


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Anatomy_Gray. One of the potential problems with hernias is that bowel and fat may become stuck within the hernial sac. This can cause appreciable pain and bowel obstruction, necessitating urgent surgery. Another potential risk is strangulation of the hernia, in which the blood supply to the bowel is cut off at the neck of the hernial sac, rendering the bowel ischemic and susceptible to perforation (Fig. 4.51). The hernial sac of an indirect inguinal hernia enters the deep inguinal ring and passes through the inguinal canal. If the hernia is large enough, the hernial sac may emerge through the superficial inguinal ring. In men, such a hernia may extend into the scrotum (Fig. 4.52). The hernial sac of a direct inguinal hernia pushes forward through the posterior wall of the inguinal canal immediately posterior to the superficial inguinal ring. The hernia protrudes directly forward medial to the inferior epigastric vessels and through the superficial inguinal ring.


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Anatomy_Gray. The differentiation between an indirect and a direct inguinal hernia is made during surgery when the inferior epigastric vessels are identified at the medial edge of the deep internal ring: An indirect hernial sac passes lateral to the inferior epigastric vessels. A direct hernia is medial to the inferior epigastric vessels. Inguinal hernias occur more commonly in men than in women possibly because men have a much larger inguinal canal than women.


Anatomy_Gray

Anatomy_Gray. A direct hernia is medial to the inferior epigastric vessels. Inguinal hernias occur more commonly in men than in women possibly because men have a much larger inguinal canal than women. A femoral hernia passes through the femoral canal and into the medial aspect of the anterior thigh. The femoral canal lies at the medial edge of the femoral sheath, which contains the femoral artery, femoral vein, and lymphatics. The neck of the femoral canal is extremely narrow and is prone to trapping bowel within the sac, so making this type of hernia irreducible and susceptible to bowel strangulation. Femoral hernias are usually acquired, are not congenital, and most commonly occur in middle-aged and elderly populations. In addition, because women generally have wider pelvises than men, they tend to occur more commonly in women.


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Anatomy_Gray. The groin can loosely be defined as the area where the leg meets the trunk near the midline. Here the abdominal muscles of the trunk blend in with the adductor muscles of the thigh, the medial end of the inguinal ligament attaches to the pubic tubercle, the pubic symphysis attaches the two pubic bones together, and the superficial (external) inguinal ring occurs. It also is in and around this region where there is considerable translation of force during most athletic and sporting activities. Pain in the groin or pubic region can be due to numerous causes, which include inflammatory changes at the pubic symphysis, insertional problems of the rectus abdominis/adductor longus, and hernias.


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Anatomy_Gray. Umbilical hernias are rare. Occasionally, they are congenital and result from failure of the small bowel to return to the abdominal cavity from the umbilical cord during development. After birth, umbilical hernias may result from incomplete closure of the umbilicus (navel). Overall, most of these hernias close in the first year of life, and surgical repair is not generally attempted until later. Para-umbilical hernias may occur in adults at and around the umbilicus and often have small necks, so requiring surgical treatment. Incisional hernias occur through a defect in a scar of a previous abdominal operation. Usually, the necks of these hernias are wide and do not therefore strangulate the viscera they contain. A spigelian hernia passes upward through the arcuate line into the lateral border at the lower part of the posterior rectus sheath. It may appear as a tender mass on one side of the lower anterior abdominal wall.


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Anatomy_Gray. Abdominopelvic cavity hernias can also develop in association with the pelvic walls, and sites include the obturator canal, the greater sciatic foramen and above and below the piriformis muscle. In the clinic A small volume of peritoneal fluid within the peritoneal cavity lubricates movement of the viscera suspended in the abdominal cavity. It is not detectable on any available imaging such as ultrasound or computed tomography. In various pathological conditions (e.g., in liver cirrhosis, acute pancreatitis, or heart failure) the volume of peritoneal fluid can increase; this is known as ascites. In cases of high volume of free intraperitoneal fluid, marked abdominal distention can be observed (Fig. 4.56). The peritoneal space has a large surface area, which facilitates the spread of disease through the peritoneal cavity and over the bowel and visceral surfaces. Conversely, this large surface area can be used for administering certain types of treatment and a number of procedures.


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Anatomy_Gray. Patients with obstructive hydrocephalus (an excessive accumulation of cerebrospinal fluid within the cerebral ventricular system) require continuous drainage of this fluid. This is achieved by placing a fine-bore catheter through the skull into the cerebral ventricles and placing the extracranial part of the tube beneath the scalp and skin of the neck and chest wall, and then through the abdominal wall into the peritoneal cavity. Cerebrospinal fluid drains through the tube into the peritoneal cavity, where it is absorbed. People who develop renal failure require dialysis to live. There are two methods.


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Anatomy_Gray. People who develop renal failure require dialysis to live. There are two methods. In the first method (hemodialysis), blood is taken from the circulation, dialyzed through a complex artificial membrane, and returned to the body. A high rate of blood flow is required to remove excess body fluid, exchange electrolytes, and remove noxious metabolites. To accomplish this, either an arteriovenous fistula is established surgically (by connecting an artery to a vein, usually in the upper limb, and requiring approximately six weeks to “mature”) and is cannulated each time the patient returns for dialysis, or a large-bore cannula is placed into the right atrium, through which blood can be aspirated and returned.


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Anatomy_Gray. In the second method (peritoneal dialysis), the peritoneum is used as the dialysis membrane. The large surface area of the peritoneal cavity is an ideal dialysis membrane for fluid and electrolyte exchange. To accomplish dialysis, a small tube is inserted through the abdominal wall and dialysis fluid is injected into the peritoneal cavity. Electrolytes and molecules are exchanged across the peritoneum between the fluid and blood. Once dialysis is completed, the fluid is drained. Peritoneal spread of disease


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Anatomy_Gray. Peritoneal spread of disease The large surface area of the peritoneal cavity allows infection and malignant disease to spread easily throughout the abdomen (Fig. 4.57). If malignant cells enter the peritoneal cavity by direct invasion (e.g., from colon or ovarian cancer), spread may be rapid. Similarly, a surgeon excising a malignant tumor and releasing malignant cells into the peritoneal cavity may cause an appreciable worsening of the patient’s prognosis. Infection can also spread across the large surface area. The peritoneal cavity can also act as a barrier to, and container of, disease. Intraabdominal infection therefore tends to remain below the diaphragm rather than spread into other body cavities.


Anatomy_Gray

Anatomy_Gray. The peritoneal cavity can also act as a barrier to, and container of, disease. Intraabdominal infection therefore tends to remain below the diaphragm rather than spread into other body cavities. A perforated bowel (e.g., caused by a perforated duodenal ulcer) often leads to the release of gas into the peritoneal cavity. This peritoneal gas can be easily visualized on an erect chest radiograph—gas can be demonstrated in extremely small amounts beneath the diaphragm. A patient with severe abdominal pain and subdiaphragmatic gas needs a laparotomy (Fig. 4.58). In the clinic The greater omentum


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Anatomy_Gray. In the clinic The greater omentum When a laparotomy is performed and the peritoneal cavity is opened, the first structure usually encountered is the greater omentum. This fatty double-layered vascular membrane hangs like an apron from the greater curvature of the stomach, drapes over the transverse colon, and lies freely suspended within the abdominal cavity. It is often referred to as the “policeman of the abdomen” because of its apparent ability to migrate to any inflamed area and wrap itself around the organ to wall off inflammation. When a part of bowel becomes inflamed, it ceases peristalsis. This aperistaltic area is referred to as a local paralytic ileus. The remaining noninflamed part of the bowel continues to move and “massages” the greater omentum to the region where there is no peristalsis. The localized inflammatory reaction spreads to the greater omentum, which then adheres to the diseased area of bowel.


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Anatomy_Gray. The greater omentum is also an important site for metastatic tumor spread. Direct omental spread by a transcoelomic route is common for carcinoma of the ovary. As the metastases develop within the greater omentum, it becomes significantly thickened. In computed tomography imaging and during laparotomy, the thickened omentum is referred to as an “omental cake.” In the clinic Epithelial transition between the abdominal esophagus and stomach


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Anatomy_Gray. In the clinic Epithelial transition between the abdominal esophagus and stomach The gastroesophageal junction is demarcated by a transition from one epithelial type (nonkeratinized stratified squamous epithelium) to another epithelial type (columnar epithelium). In some people, the histological junction does not lie at the anatomical gastroesophageal junction but occurs more proximally in the lower third of the esophagus. This may predispose these people to esophageal ulceration and is also associated with an increased risk of adenocarcinoma. In certain conditions, like gastroesophageal reflux, the stratified squamous epithelium in the esophagus can undergo metaplasia and the epithelium in the lower esophagus is replaced by columnar epithelium, a condition called Barrett’s esophagus. The presence of Barrett’s esophagus predisposes these people to the development of esophageal malignancy (adenocarcinoma). In the clinic


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Anatomy_Gray. Duodenal ulcers usually occur in the superior part of the duodenum and are much less common than they were 50 years ago. At first, there was no treatment and patients died from hemorrhage or peritonitis. As surgical techniques developed, patients with duodenal ulcers were subjected to extensive upper gastrointestinal surgery to prevent ulcer recurrence and for some patients the treatment was dangerous. As knowledge and understanding of the mechanisms for acid secretion in the stomach increased, drugs were developed to block acid stimulation and secretion indirectly (histamine H2-receptor antagonists) and these have significantly reduced the morbidity and mortality rates of this disease. Pharmacological therapy can now directly inhibit the cells of the stomach that produce acid with, for example, proton pump inhibitors. Patients are also screened for the bacteria Helicobacter pylori, which when eradicated (by antibiotic treatment) significantly reduces duodenal ulcer formation.


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Anatomy_Gray. Anatomically, duodenal ulcers tend to occur either anteriorly or posteriorly. Posterior duodenal ulcers erode either directly onto the gastroduodenal artery or, more commonly, onto the posterior superior pancreaticoduodenal artery, which can produce torrential hemorrhage, which may be fatal in some patients. Treatment may involve extensive upper abdominal surgery with ligation of the vessels or by endovascular means whereby the radiologist may place a very fine catheter retrogradely from the femoral artery into the celiac artery. The common hepatic artery and the gastroduodenal artery are cannulated and the bleeding area may be blocked using small coils, which stem the flow of blood.


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Anatomy_Gray. Anterior duodenal ulcers erode into the peritoneal cavity, causing peritonitis. This intense inflammatory reaction and the local ileus promote adhesion of the greater omentum, which attempts to seal off the perforation. The stomach and duodenum usually contain considerable amounts of gas, which enters the peritoneal cavity and can be observed on a chest radiograph of an erect patient as subdiaphragmatic gas. In most instances, treatment for the ulcer perforation is surgical. In the clinic Examination of the upper and lower It is often necessary to examine the esophagus, stomach, duodenum, proximal jejunum, and colon for disease. After taking an appropriate history and examining the patient, most physicians arrange a series of simple blood tests to look for bleeding, inflammation, and tumors. The next steps in the investigation assess the three components of any loop of bowel, namely, the lumen, the wall, and masses extrinsic to the bowel, which may compress or erode into it.


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Anatomy_Gray. Examination of the bowel lumen Barium sulfate solutions may be swallowed by the patient and can be visualized using an X-ray fluoroscopy unit. The lumen can be examined for masses (e.g., polyps and tumors) and peristaltic waves can be assessed. Patients may also be given carbon dioxide–releasing granules to fill the stomach so that the barium thinly coats the mucosa, resulting in images displaying fine mucosal detail. These tests are relatively simple and can be used to image the esophagus, stomach, duodenum, and small bowel. For imaging the large bowel, a barium enema can be used to introduce barium sulfate into the colon. Colonoscopy and CT colonography are also used. Examination of the bowel wall and extrinsic masses


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Anatomy_Gray. Examination of the bowel wall and extrinsic masses Endoscopy is a minimally invasive diagnostic medical procedure that can be used to assess the interior surfaces of an organ by inserting a tube into the body. The instrument is typically made of a flexible plastic material through which a light source and eyepiece are attached at one end. The images are then projected to a monitor. Some systems allow passage of small instruments through the main bore of the endoscope to obtain biopsies and to also undertake small procedures (e.g., the removal of polyps). In gastrointestinal and abdominal medicine an endoscope is used to assess the esophagus, stomach, duodenum, and proximal small bowel (Figs. 4.72 to 4.75). The tube is swallowed by the patient under light sedation and is extremely well tolerated.


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Anatomy_Gray. Assessment of the colon (colonoscopy) is performed by passage of the long flexible tube through the anus and into the rectum. The endoscope is then advanced into the colon to the cecum and sometimes to the terminal ileum. The patient undergoes bowel preparation before the examination to allow good visualization of the entire large bowel. Specially designed solutions are taken orally to help clear the bowel of fecal material. Air, water, and suction may be used during the examination to improve visualization. Biopsies, polyp removal, cauterization of bleeding, and stent placement can also be performed using additional instruments that can be passed through special openings in the colonoscope.


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Anatomy_Gray. Cross sectional imaging using computed tomography or magnetic resonance is another way to assess the bowel lumen and wall. Magnetic resonance is particularly useful in assessment of the small bowel because it allows dynamic assessment of bowel distention and motility and provides good visualization of segmental or continuous bowel wall thickening and mural or mucosal ulcerations and also can demonstrate increased vascularity of the small bowel mesentery (Fig. 4.76). It is usually performed in patients with inflammatory bowel diseases, such as Crohn’s disease.


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Anatomy_Gray. CT colonography (also called virtual colonoscopy or CT pneumocolon) is an alternative way to visualize and assess the colon for abnormal lesions such as polyps or strictures with the use spiral CT to produce high-resolution 3D views of the large bowel. It is less invasive than traditional colonoscopy, but to achieve good-quality images the patient needs to take bowel preparations to ensure bowel cleansing, and the colon needs to be insufflated with CO2. If a tumor is present (Fig. 4.77), both CT and MRI are used to assess regional disease (MRI), abnormal lymph nodes (MRI, CT), and distant metastases (CT). In the clinic


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Anatomy_Gray. In the clinic A Meckel’s diverticulum (Fig. 4.78) is the remnant of the proximal part of the yolk stalk (vitelline duct) that extends into the umbilical cord in the embryo and lies on the antimesenteric border of the ileum. It appears as a blind-ended tubular outgrowth of bowel. Although it is an uncommon finding (occurring in approximately 2% of the population), it is always important to consider the diagnosis of Meckel’s diverticulum because it does produce symptoms in a small number of patients. It may contain gastric mucosa and therefore lead to ulceration and hemorrhage. Other typical complications include intussusception, diverticulitis, and obstruction. In the clinic


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Anatomy_Gray. In the clinic These imaging techniques can provide important information about the wall of the bowel that may not be obtained from barium or endoscopic studies. Thickening of the wall may indicate inflammatory change or tumor and is always regarded with suspicion. If a tumor is demonstrated, the locoregional spread can be assessed, along with lymphadenopathy and metastatic spread. Endoscopic ultrasound (EUS) uses a small ultrasound device placed on the end of the endoscope to assess the upper gastrointestinal tract. It can produce extremely high-powered views of the mucosa and submucosa and therefore show whether a tumor is resectable. It also provides guidance to the clinician when taking a biopsy. In the clinic Carcinoma of the stomach


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Anatomy_Gray. In the clinic Carcinoma of the stomach Carcinoma of the stomach is a common gastrointestinal malignancy. Chronic gastric inflammation (gastritis), pernicious anemia, and polyps predispose to the development of this aggressive cancer, which is usually not diagnosed until late in the course of the disease. Symptoms include vague epigastric pain, early fullness with eating, bleeding leading to chronic anemia, and obstruction.


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Anatomy_Gray. The diagnosis may be made using barium and conventional radiology or endoscopy, which allows a biopsy to be obtained at the same time. Ultrasound scanning is used to check the liver for metastatic spread, and, if negative, computed tomography is carried out to assess for surgical resectability. If carcinoma of the stomach is diagnosed early, a curative surgical resection is possible. However, because most patients do not seek treatment until late in the disease, the overall 5-year survival rate is between 5% and 20%, with a mean survival time of between 5 and 8 months. In the clinic


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Anatomy_Gray. In the clinic Acute appendicitis is an abdominal emergency. It usually occurs when the appendix is obstructed by either a fecalith or enlargement of the lymphoid nodules. Within the obstructed appendix, bacteria proliferate and invade the appendix wall, which becomes damaged by pressure necrosis. In some instances, this may resolve spontaneously; in other cases, inflammatory change (Figs. 4.86 and 4.87) continues and perforation ensues, which may lead to localized or generalized peritonitis. Most patients with acute appendicitis have localized tenderness in the right groin. Initially, the pain begins as a central, periumbilical, colicky type of pain, which tends to come and go. After 6 to 10 hours, the pain tends to localize in the right iliac fossa and becomes constant. Patients may develop a fever, nausea, and vomiting. The etiology of the pain for appendicitis is described in Case 1 of Chapter 1 on p. 48. The treatment for appendicitis is appendectomy. In the clinic


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Anatomy_Gray. The treatment for appendicitis is appendectomy. In the clinic Congenital disorders of the gastrointestinal tract The normal positions of the abdominal viscera result from a complex series of rotations that the gut tube undergoes and from the growth of the abdominal cavity to accommodate changes in the size of the developing organs (see pp. 265-268). A number of developmental anomalies can occur during gut development, many of which appear in the neonate or infant, and some of which are surgical emergencies. Occasionally, such disorders are diagnosed only in adults.


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Anatomy_Gray. Malrotation is incomplete rotation and fixation of the midgut after it has passed from the umbilical sac and returned to the abdominal coelom (Figs. 4.93 and 4.94). The proximal attachment of the small bowel mesentery begins at the suspensory muscle of duodenum (ligament of Treitz), which determines the position of the duodenojejunal junction. The mesentery of the small bowel ends at the level of the ileocecal junction in the right lower quadrant. This long line of fixation of the mesentery prevents accidental twists of the gut. If the duodenojejunal flexure or the cecum does not end up in its usual site, the origin of the small bowel mesentery shortens, which permits twisting of the small bowel around the axis of the superior mesenteric artery. Twisting of the bowel, in general, is termed volvulus. Volvulus of the small bowel may lead to a reduction of blood flow and infarction.


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Anatomy_Gray. In some patients, the cecum ends up in the midabdomen. From the cecum and the right side of the colon a series of peritoneal folds (Ladd’s bands) develop that extend to the right undersurface of the liver and compress the duodenum. A small bowel volvulus may then occur as well as duodenal obstruction. Emergency surgery may be necessary to divide the bands. In the clinic A bowel obstruction can be either functional or due to a true obstruction. Mechanical obstruction is caused by an intraluminal, mural, or extrinsic mass which can be secondary to a foreign body, obstructing tumor in the wall, or extrinsic compression from an adhesion, or embryological band (Fig. 4.95).


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Anatomy_Gray. A functional obstruction is usually due to an inability of the bowel to peristalse, which again has a number of causes, and most frequently is a postsurgical state due to excessive intraoperative bowel handling. Other causes may well include abnormality of electrolytes (e.g., sodium and potassium) rendering the bowel paralyzed until correction has occurred. The signs and symptoms of obstruction depend on the level at which the obstruction has occurred. The primary symptom is central abdominal, intermittent, colicky pain as the peristaltic waves try to overcome the obstruction. Abdominal distention will occur if it is a low obstruction (distal), allowing more proximal loops of bowel to fill with fluid. A high obstruction (in the proximal small bowel) may not produce abdominal distention. Vomiting and absolute constipation, including the inability to pass flatus, will ensue.


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Anatomy_Gray. Vomiting and absolute constipation, including the inability to pass flatus, will ensue. Early diagnosis is important because considerable fluid and electrolytes enter the bowel lumen and fail to be reabsorbed, which produces dehydration and electrolyte abnormalities. Furthermore, the bowel continues to distend, compromising the blood supply within the bowel wall, which may lead to ischemia and perforation. The symptoms and signs are variable and depend on the level of obstruction. Small bowel obstruction is typically caused by adhesions following previous surgery, and history should always be sought for any operations or abdominal interventions (e.g., previous appendectomy). Other causes include bowel passing into hernias (e.g., inguinal) and bowel twisting on its own mesentery (volvulus). Examination of hernial orifices is mandatory in patients with bowel obstruction (Fig. 4.96).


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Anatomy_Gray. Large bowel obstruction is commonly caused by a tumor. Other potential causes include hernias and inflammatory diverticular disease of the sigmoid colon (Fig. 4.97). The treatment is intravenous replacement of fluid and electrolytes, analgesia, and relief of obstruction. The passage of a nasogastric tube allows aspiration of fluid from the stomach. In many instances, small bowel obstruction, typically secondary to adhesions, will settle with nonoperative management. Large bowel obstruction may require an urgent operation to remove the obstructing lesion, or a temporary bypass procedure (e.g., defunctioning colostomy) (Fig. 4.98). In the clinic


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Anatomy_Gray. In the clinic Diverticular disease is the development of multiple colonic diverticula, predominantly throughout the sigmoid colon, though the whole colon may be affected (Fig. 4.99). The sigmoid colon has the smallest diameter of any portion of the colon and is therefore the site where intraluminal pressure is potentially the highest. Poor dietary fiber intake and obesity are also linked to diverticular disease. The presence of multiple diverticula does not necessarily mean the patient requires any treatment. Moreover, many patients have no other symptoms or signs. Patients tend to develop symptoms and signs when the neck of the diverticulum becomes obstructed by feces and becomes infected. Inflammation may spread along the wall, causing abdominal pain. When the sigmoid colon becomes inflamed (diverticulitis), abdominal pain and fever ensue (Fig. 4.100).


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Anatomy_Gray. Because of the anatomical position of the sigmoid colon there are a number of complications that may occur. The diverticula can perforate to form an abscess in the pelvis. The inflammation may produce an inflammatory mass, obstructing the left ureter. Inflammation may also spread to the bladder, producing a fistula between the sigmoid colon and the bladder. In these circumstances patients may develop a urinary tract infection and rarely have fecal material and gas passing per urethra. The diagnosis is based upon clinical examination and often CT scanning. In the first instance, patients will be treated with antibiotic therapy; however, a surgical resection may be necessary if symptoms persist. In the clinic It is occasionally necessary to surgically externalize bowel to the anterior abdominal wall. Externalization of bowel plays an important role in patient management. These extraanatomical bypass procedures use our anatomical knowledge and in many instances are life saving.


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Anatomy_Gray. Gastrostomy is performed when the stomach is attached to the anterior abdominal wall and a tube is placed through the skin into the stomach. Typically this is performed to feed the patient when it is impossible to take food and fluid orally (e.g., complex head and neck cancer). The procedure can be performed either surgically or through a direct needlestick puncture under sedation in the anterior abdominal wall. Similarly the jejunum is brought to the anterior abdominal wall and fixed. The jejunostomy is used as a site where a feeding tube is placed through the anterior abdominal wall into the proximal efferent small bowel. An ileostomy is performed when small bowel contents need to be diverted from the distal bowel. An ileostomy is often performed to protect a distal surgical anastomosis, such as in the colon to allow healing after surgery.


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Anatomy_Gray. There are a number of instances when a colostomy may be necessary. In many circumstances it is performed to protect the distal large bowel after surgery. A further indication would include large bowel obstruction with imminent perforation wherein a colostomy allows decompression of the bowel and its contents. This is a safe and temporizing procedure performed when the patient is too unwell for extensive bowel surgery. It is relatively straightforward and carries reduced risk, preventing significant morbidity and mortality. An end colostomy is necessary when the patient has undergone a surgical resection of the rectum and anus (typically for cancer).


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Anatomy_Gray. An end colostomy is necessary when the patient has undergone a surgical resection of the rectum and anus (typically for cancer). An ileal conduit is an extraanatomical procedure and is performed after resection of the bladder for tumor. In this situation a short segment of small bowel is identified. The bowel is divided twice to produce a 20-cm segment of small bowel on its own mesentery. This isolated segment of bowel is used as a conduit. The remaining bowel is joined together. The proximal end is anastomosed to the ureters, and the distal end is anastomosed to the anterior abdominal wall. Hence, urine passes from the kidneys into the ureters and through the short segment of small bowel to the anterior abdominal wall.


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Anatomy_Gray. When patients have either an ileostomy, colostomy, or ileal conduit it is necessary for them to fix a collecting bag onto the anterior abdominal wall. Contrary to one’s initial thoughts these bags are tolerated extremely well by most patients and allow patients to live a nearly normal and healthy life. In the clinic The pancreas develops from ventral and dorsal buds from the foregut. The dorsal bud forms most of the head, neck, and body of the pancreas. The ventral bud rotates around the bile duct to form part of the head and the uncinate process. If the ventral bud splits (becomes bifid), the two segments may encircle the duodenum. The duodenum is therefore constricted and may even undergo atresia, and be absent at birth because of developmental problems. After birth, the child may fail to thrive and may vomit due to poor gastric emptying.


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Anatomy_Gray. Sometimes an annular pancreas is diagnosed in utero by ultrasound scanning. The obstruction of the duodenum may prevent the fetus from swallowing enough amniotic fluid, which may increase the overall volume of amniotic fluid in the amniotic sac surrounding the fetus (polyhydramnios). In the clinic


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Anatomy_Gray. In the clinic Pancreatic cancer accounts for a significant number of deaths and is often referred to as the “silent killer.” Malignant tumors of the pancreas may occur anywhere within the pancreas but are most frequent within the head and the neck. There are a number of nonspecific findings in patients with pancreatic cancer, including upper abdominal pain, loss of appetite, and weight loss. Depending on the exact site of the cancer, obstruction of the bile duct may occur, which can produce obstructive jaundice. Although surgery is indicated in patients where there is a possibility of cure, most detected cancers have typically spread locally, invading the portal vein and superior mesenteric vessels, and may extend into the porta hepatis. Lymph node spread also is common and these factors would preclude curative surgery.


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Anatomy_Gray. Given the position of the pancreas, a surgical resection is a complex procedure involving resection of the region of pancreatic tumor usually with part of the duodenum, necessitating a complex bypass procedure. In the clinic Segmental anatomy of the liver For many years the segmental anatomy of the liver was of little importance. However, since the development of liver resection surgery, the size, shape, and segmental anatomy of the liver have become clinically important, especially with regard to liver resection for metastatic disease. Indeed, with detailed knowledge of the segments, curative surgery can be performed in patients with tumor metastases.


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Anatomy_Gray. Indeed, with detailed knowledge of the segments, curative surgery can be performed in patients with tumor metastases. The liver is divided by the principal plane, which divides the organ into halves of approximately equal size. This imaginary line is defined by a parasagittal line that passes through the gallbladder fossa to the inferior vena cava. It is in this plane that the middle hepatic vein is found. Importantly, the principal plane divides the left half of the liver from the right half. The lobes of the liver are unequal in size and bear only little relevance to operative anatomy. The traditional eight-segment anatomy of the liver relates to the hepatic arterial, portal, and biliary drainage of these segments (Fig. 4.116). The caudate lobe is defined as segment I, and the remaining segments are numbered in a clockwise fashion up to segment VIII. The features are extremely consistent between individuals.


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Anatomy_Gray. The caudate lobe is defined as segment I, and the remaining segments are numbered in a clockwise fashion up to segment VIII. The features are extremely consistent between individuals. From a surgical perspective, a right hepatectomy would involve division of the liver in the principal plane in which segments V, VI, VII, and VIII would be removed, leaving segments I, II, III, and IV. In the clinic Gallstones are present in approximately 10% of people over the age of 40 and are more common in women. They consist of a variety of components but are predominantly a mixture of cholesterol and bile pigment. They may undergo calcification, which can be demonstrated on plain radiographs. Gallstones may be visualized incidentally as part of a routine abdominal ultrasound scan (Fig. 4.117) or on a plain radiograph.


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Anatomy_Gray. The easiest way to confirm the presence of gallstones is by performing a fasting ultrasound examination of the gallbladder. The patient refrains from eating for 6 hours to ensure the gallbladder is well distended and there is little shadowing from overlying bowel gas. The examination may also identify bile duct dilation and the presence of cholecystitis. Magnetic resonance cholangiopancreatography (MRCP) is another way to image the gallbladder and biliary tree. MRCP uses fluid present in the bile ducts and in the pancreatic duct as a contrast agent to show stones as well as filling defects within the gallbladder and intrahepatic or extrahepatic bile ducts. It can demonstrate strictures in the biliary tree and can also be used to visualize liver and pancreatic anatomy (Fig. 4.118).


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Anatomy_Gray. From time to time, gallstones impact in the region of Hartmann’s pouch, which is a bulbous region of the neck of the gallbladder. When the gallstone lodges in this area, the gallbladder cannot empty normally and contractions of the gallbladder wall produce severe pain. If this persists, a cholecystectomy (removal of the gallbladder) may be necessary. Sometimes the gallbladder may become inflamed (cholecystitis). If the inflammation involves the related parietal peritoneum of the diaphragm, pain may not only occur in the right upper quadrant of the abdomen but may also be referred to the shoulder on the right side. This referred pain is due to the innervation of the visceral peritoneum of the diaphragm by spinal cord levels (C3 to C5) that also innervate skin over the shoulder. In this case, one somatic sensory region of low sensory output (diaphragm) is referred to another somatic sensory region of high sensory output (dermatomes).


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Anatomy_Gray. From time to time, small gallstones pass into the bile duct and are trapped in the region of the sphincter of the ampulla, which obstructs the flow of bile into the duodenum. This, in turn, produces jaundice.


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Anatomy_Gray. Endoscopic retrograde cholangiopancreatography (ERCP) can be undertaken to remove obstructing gallstones within the biliary tree. This procedure combines endoluminal endoscopy with fluoroscopy to diagnose and treat problems in the biliary and pancreatic ducts. An endoscope with a side-viewing optical system is advanced through the esophagus and stomach and placed in the second part of the duodenum where the major papilla (the ampulla of Vater) is identified. This is where the pancreatic duct converges with the common bile duct. The papilla is initially examined for possible abnormalities (stuck stone or malignant growth) and a biopsy may be taken if necessary. Then either the bile duct or pancreatic duct is cannulated and a small amount of radiopaque contrast medium is injected to visualize either the bile duct (cholangiogram) or pancreatic duct (pancreatogram) (Fig. 4.119). If a stone is present, it can be removed with a stone basket or an extraction balloon. Usually, a


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Anatomy_Gray. to visualize either the bile duct (cholangiogram) or pancreatic duct (pancreatogram) (Fig. 4.119). If a stone is present, it can be removed with a stone basket or an extraction balloon. Usually, a sphincterotomy is performed before stone removal to ease its passage through the distal bile duct.


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Anatomy_Gray. In cases of biliary tree obstruction caused by benign or malignant strictures, a stent can be placed into the common bile duct or into one of the main hepatic ducts to allow opening of the narrowed segment. The patency of the newly inserted stent is confirmed by instillation of more contrast medium to demonstrate free flow of contrast through the stent. In the clinic Jaundice is a yellow discoloration of the skin caused by excess bile pigment (bilirubin) within the plasma. The yellow color is best appreciated by looking at the normally white sclerae of the eyes, which turn yellow. The extent of the elevation of the bile pigments and the duration for which they have been elevated account for the severity of jaundice. Simplified explanation to understanding the types of jaundice and their anatomical causes


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Anatomy_Gray. Simplified explanation to understanding the types of jaundice and their anatomical causes When red blood cells are destroyed by the reticuloendothelial system, the iron from the hemoglobin molecule is recycled, whereas the porphyrin ring (globin) compounds are broken down to form fat-soluble bilirubin. On reaching the liver via the bloodstream, the fat-soluble bilirubin is converted to a water-soluble form of bilirubin. This water-soluble bilirubin is secreted into the biliary tree and then in turn into the bowel, where it forms the dark color of the stool. This type of jaundice is usually produced by conditions where there is an excessive breakdown of red blood cells (e.g., in incompatible blood transfusion and hemolytic anemia).


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Anatomy_Gray. This type of jaundice is usually produced by conditions where there is an excessive breakdown of red blood cells (e.g., in incompatible blood transfusion and hemolytic anemia). The complex biochemical reactions for converting fat-soluble into water-soluble bilirubin may be affected by inflammatory change within the liver (e.g., from hepatitis or chronic liver disease, such as liver cirrhosis) and poisons (e.g., paracetamol overdose). Any obstruction of the biliary tree can produce jaundice, but the two most common causes are gallstones within the bile duct and an obstructing tumor at the head of the pancreas. In the clinic From a clinical point of view, there are two main categories of spleen disorders: rupture and enlargement.


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Anatomy_Gray. In the clinic From a clinical point of view, there are two main categories of spleen disorders: rupture and enlargement. This tends to occur when there is localized trauma to the left upper quadrant. It may be associated with left lower rib fractures. Because the spleen has such an extremely thin capsule, it is susceptible to injury even when there is no damage to surrounding structures, and because the spleen is highly vascular, when ruptured, it bleeds profusely into the peritoneal cavity. Splenic rupture should always be suspected with blunt abdominal injury. Current treatments preserve as much of the spleen as possible, but some patients require splenectomy.


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Anatomy_Gray. The spleen is an organ of the reticuloendothelial system involved in hematopoiesis and immunological surveillance. Diseases that affect the reticuloendothelial system (e.g., leukemia or lymphoma) may produce generalized lymphadenopathy and enlargement of the spleen (splenomegaly) (Fig. 4.120). The spleen often enlarges when performing its normal physiological functions, such as when clearing microorganisms and particulates from the circulation, producing increased antibodies in the course of sepsis, or removing deficient or destroyed erythrocytes (e.g., in thalassemia and spherocytosis). Splenomegaly may also be a result of increased venous pressure caused by congestive heart failure, splenic vein thrombosis, or portal hypertension. An enlarged spleen is prone to rupture. In the clinic Vascular supply to the gastrointestinal system


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Anatomy_Gray. In the clinic Vascular supply to the gastrointestinal system The abdominal parts of the gastrointestinal system are supplied mainly by the celiac trunk and the superior mesenteric and inferior mesenteric arteries (Fig. 4.129): The celiac trunk supplies the lower esophagus, stomach, superior part of the duodenum, and proximal half of the descending part of the duodenum. The superior mesenteric artery supplies the rest of the duodenum, the jejunum, the ileum, the ascending colon, and the proximal two-thirds of the transverse colon. The inferior mesenteric artery supplies the rest of the transverse colon, the descending colon, the sigmoid colon, and most of the rectum.


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Anatomy_Gray. The inferior mesenteric artery supplies the rest of the transverse colon, the descending colon, the sigmoid colon, and most of the rectum. Along the descending part of the duodenum there is a potential watershed area between the celiac trunk blood supply and the superior mesenteric arterial blood supply. It is unusual for this area to become ischemic, whereas the watershed area between the superior mesenteric artery and the inferior mesenteric artery, at the splenic flexure, is extremely vulnerable to ischemia. In certain disease states, the region of the splenic flexure of the colon can become ischemic. When this occurs, the mucosa sloughs off, rendering the patient susceptible to infection and perforation of the large bowel, which then requires urgent surgical attention.


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Anatomy_Gray. Arteriosclerosis may occur throughout the abdominal aorta and at the openings of the celiac trunk and the superior mesenteric and inferior mesenteric arteries. Not infrequently, the inferior mesenteric artery becomes occluded. Interestingly, many of these patients do not suffer any complications, because anastomoses between the right, middle, and left colic arteries gradually enlarge, forming a continuous marginal artery. The distal large bowel therefore becomes supplied by this enlarged marginal artery (marginal artery of Drummond), which replaces the blood supply of the inferior mesenteric artery (Fig. 4.130).


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Anatomy_Gray. If the openings of the celiac trunk and superior mesenteric artery become narrowed, the blood supply to the gut is diminished. After a heavy meal, the oxygen demand of the bowel therefore outstrips the limited supply of blood through the stenosed vessels, resulting in severe pain and discomfort (mesenteric angina). Patients with this condition tend not to eat because of the pain and rapidly lose weight. The diagnosis is determined by aortic angiography, and the stenoses of the celiac trunk and superior mesenteric artery are best appreciated in the lateral view. In the clinic Cirrhosis is a complex disorder of the liver, the diagnosis of which is confirmed histologically. When a diagnosis is suspected, a liver biopsy is necessary. Cirrhosis is characterized by widespread hepatic fibrosis interspersed with areas of nodular regeneration and abnormal reconstruction of preexisting lobular architecture. The presence of cirrhosis implies previous or continuing liver cell damage.


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Anatomy_Gray. The etiology of cirrhosis is complex and includes toxins (alcohol), viral inflammation, biliary obstruction, vascular outlet obstruction, nutritional (malnutrition) causes, and inherited anatomical and metabolic disorders. As the cirrhosis progresses, the intrahepatic vasculature is distorted, which in turn leads to increased pressure in the portal vein and its draining tributaries (portal hypertension). Portal hypertension produces increased pressure in the splenic venules, leading to splenic enlargement. At the sites of portosystemic anastomosis (see below), large dilated veins (varices) develop. These veins are susceptible to bleeding and may produce marked blood loss, which in some instances can be fatal.


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Anatomy_Gray. The liver is responsible for the production of numerous proteins, including those of the clotting cascade. Any disorder of the liver (including infection and cirrhosis) may decrease the production of these proteins and so prevent adequate blood clotting. Patients with severe cirrhosis of the liver have a significant risk of serious bleeding, even from small cuts; in addition, when varices rupture, there is a danger of rapid exsanguination. As the liver progressively fails, the patient develops salt and water retention, which produces skin and subcutaneous edema. Fluid (ascites) is also retained in the peritoneal cavity, which can hold many liters. The poorly functioning liver cells (hepatocytes) are unable to break down blood and blood products, leading to an increase in the serum bilirubin level, which manifests as jaundice.


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Anatomy_Gray. The poorly functioning liver cells (hepatocytes) are unable to break down blood and blood products, leading to an increase in the serum bilirubin level, which manifests as jaundice. With the failure of normal liver metabolism, toxic metabolic by-products do not convert to nontoxic metabolites. This buildup of noxious compounds is made worse by the numerous portosystemic shunts, which allow the toxic metabolites to bypass the liver. Patients may develop severe neurological features, called hepatic encephalopathy, that can manifest as acute confusion, epileptic fits, or psychotic state. Hepatic encephalopathy is one of the urgent criteria for liver transplantation; if the condition is not reversed, it leads to irreversible neurological damage and death.


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Anatomy_Gray. The hepatic portal system drains blood from the visceral organs of the abdomen to the liver. In normal individuals, 100% of the portal venous blood flow can be recovered from the hepatic veins, whereas in patients with elevated portal vein pressure (e.g., from cirrhosis), there is significantly less blood flow to the liver. The rest of the blood enters collateral channels, which drain into the systemic circulation at specific points (Fig. 4.133). The largest of these collaterals occur at: the gastroesophageal junction around the cardia of the stomach—where the left gastric vein and its tributaries form a portosystemic anastomosis with tributaries to the azygos system of veins of the caval system; the anus—the superior rectal vein of the portal system anastomoses with the middle and inferior rectal veins of the systemic venous system; and the anterior abdominal wall around the umbilicus—the para-umbilical veins anastomose with veins on the anterior abdominal wall.


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Anatomy_Gray. When the pressure in the portal vein is elevated, venous enlargement (varices) tend to occur at and around the sites of portosystemic anastomoses and these enlarged veins are called: varices at the anorectal junction, esophageal varices at the gastroesophageal junction, and caput medusae at the umbilicus. Esophageal varices are susceptible to trauma and, once damaged, may bleed profusely, requiring urgent surgical intervention. In the clinic


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Anatomy_Gray. Esophageal varices are susceptible to trauma and, once damaged, may bleed profusely, requiring urgent surgical intervention. In the clinic Surgery for obesity is also known as weight loss surgery and bariatric surgery. This type of surgery has become increasingly popular over the last few years for patients who are unable to achieve significant weight loss through appropriate diet modification and exercise programs. It is often regarded as a last resort. Importantly, we have to recognize the increasing medical impact that overweight patients pose. With obesity the patient is more likely to develop diabetes and cardiovascular problems and may suffer from increased general health disorders. All of these have a significant impact on health care budgeting and are regarded as serious conditions for the “health of a nation.”


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Anatomy_Gray. There are a number of surgical options to treat obesity. Surgery for patients who are morbidly obese can be categorized into two main groups: malabsorptive procedures and restrictive procedures. There are a variety of bypass procedures that produce a malabsorption state, preventing further weight gain and also producing weight loss. There are complications, which may include anemia, osteoporosis, and diarrhea (e.g., jejunoileal bypass). Restrictive procedures involve placing a band or stapling in or around the stomach to decrease the size of the organ. This reduction produces an earlier feeling of satiety and prevents the patient from overeating. Probably the most popular procedure currently in the United States is gastric bypass surgery. This procedure involves stapling the proximal stomach and joining a loop of small bowel to the small gastric remnant. The procedure is usually performed by fashioning a Roux-en-Y loop with alimentary and pancreaticobiliary limbs.


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Anatomy_Gray. The other type of the procedure, sleeve gastrectomy, is increasing in popularity because it can be used in patients deemed to be at high risk for gastric bypass surgery. It involves reduction of the gastric lumen by removing a large portion of the stomach along the greater curvature. Any overweight patient undergoing surgery faces significant risk and increased morbidity, with mortality rates from 1% to 5%. In the clinic


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Anatomy_Gray. Any overweight patient undergoing surgery faces significant risk and increased morbidity, with mortality rates from 1% to 5%. In the clinic At first glance, it is difficult to appreciate why the psoas muscle sheath is of greater importance than any other muscle sheath. The psoas muscle and its sheath arise not only from the lumbar vertebrae but also from the intervertebral discs between each vertebra. This disc origin is of critical importance. In certain types of infection, the intervertebral disc is preferentially affected (e.g., tuberculosis and salmonella discitis). As the infection of the disc develops, the infection spreads anteriorly and anterolaterally. In the anterolateral position, the infection passes into the psoas muscle sheath, and spreads within the muscle and sheath, and may appear below the inguinal ligament as a mass. In the clinic To understand why a hernia occurs through the diaphragm, it is necessary to consider the embryology of the diaphragm.


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Anatomy_Gray. In the clinic To understand why a hernia occurs through the diaphragm, it is necessary to consider the embryology of the diaphragm. The diaphragm is formed from four structures— the septum transversum, the posterior esophageal mesentery, the pleuroperitoneal membrane, and the peripheral rim—which eventually fuse together, separating the abdominal cavity from the thoracic cavity. The septum transversum forms the central tendon, which develops from a mesodermal origin superior to the embryo’s head and then moves to its more adult position during folding of the cephalic portion of the embryo. Fusion of the various components of the diaphragm may fail, and hernias may occur through the failed points of fusion (Fig. 4.146). The commonest sites are: between the xiphoid process and the costal margins on the right (Morgagni’s hernia), and through an opening on the left when the pleuroperitoneal membrane fails to close the pericardioperitoneal canal (Bochdalek’s hernia).


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Anatomy_Gray. Hernias may also occur through the central tendon and through a congenitally large esophageal hiatus. Morgagni’s and Bochdalek’s hernias tend to appear at or around the time of birth or in early infancy. They allow abdominal bowel to enter the thoracic cavity, which may compress the lungs and reduce respiratory function. Most of these hernias require surgical closure of the diaphragmatic defect. However, large hernias can lead to pulmonary hypoplasia and the long-term outcome depends more on the degree of the hypoplasia rather than on the surgical repair itself. Occasionally, small defects within the diaphragm fail to permit bowel through, but do allow free movement of fluid. Patients with ascites may develop pleural effusions, while patients with pleural effusions may develop ascites when these defects are present. In the clinic


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Anatomy_Gray. In the clinic At the level of the esophageal hiatus, the diaphragm may be lax, allowing the fundus of the stomach to herniate into the posterior mediastinum (Figs. 4.147 and 4.148). This typically causes symptoms of acid reflux. Ulceration may occur and may produce bleeding and anemia. The diagnosis is usually made by barium studies or endoscopy. Hiatal hernia is often asymptomatic and is frequently found incidentally on CT imaging performed for unrelated complaints. Treatment in the first instance is by medical management, although surgery may be necessary. In the clinic


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Anatomy_Gray. In the clinic Urinary tract stones (calculi) occur more frequently in men than in women, are most common in people aged between 20 and 60 years, and are usually associated with sedentary lifestyles. The stones are polycrystalline aggregates of calcium, phosphate, oxalate, urate, and other soluble salts within an organic matrix. The urine becomes saturated with these salts, and small variations in the pH cause the salts to precipitate. Typically the patient has pain that radiates from the infrascapular region (loin) into the groin, and even into the scrotum or labia majora. Blood in the urine (hematuria) may also be noticed. Infection must be excluded because certain species of bacteria are commonly associated with urinary tract stones. The complications of urinary tract stones include infection, urinary obstruction, and renal failure. Stones may also develop within the bladder and produce marked irritation, causing pain and discomfort.


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Anatomy_Gray. The diagnosis of urinary tract stones is based upon history and examination. Stones are often visible on abdominal radiographs. Special investigations include: ultrasound scanning, which may demonstrate the dilated renal pelvis and calices when the urinary system is obstructed. This is the preferred way of imaging in pregnant women or when clinical suspicion is low. low-dose CT of the urinary tract (CT KUB), which allows the detection of even smaller stones, shows the exact level of obstruction and, based on the size, density, and location of the stone, can help the urologist plan a procedure to remove the stone if necessary (extracorporeal shock wave lithotripsy versus ureteroscopy, percutaneous nephrolithotomy, or, extremely rare these days, open surgery) (Fig. 4.156). an intravenous urogram, which will demonstrate the obstruction, pinpoint the exact level of the stone is currently less often used because access to low-dose CT KUB has increased. In the clinic


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Anatomy_Gray. an intravenous urogram, which will demonstrate the obstruction, pinpoint the exact level of the stone is currently less often used because access to low-dose CT KUB has increased. In the clinic Most tumors that arise in the kidney are renal cell carcinomas. These tumors develop from the proximal tubular epithelium. Approximately 5% of tumors within the kidney are transitional cell tumors, which arise from the urothelium of the renal pelvis. Most patients typically have blood in the urine (hematuria), pain in the infrascapular region (loin), and a mass.


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Anatomy_Gray. Renal cell tumors (Figs. 4.157 and 4.158) are unusual because not only do they grow outward from the kidney, invading the fat and fascia, but they also spread into the renal vein. This venous extension is rare for any other type of tumor, so, when seen, renal cell carcinoma should be suspected. In addition, the tumor may spread along the renal vein and into the inferior vena cava, and in rare cases can grow into the right atrium across the tricuspid valve and into the pulmonary artery. Treatment for most renal cancers is surgical removal, even when metastatic spread is present, because some patients show regression of metastases.


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Anatomy_Gray. Treatment for most renal cancers is surgical removal, even when metastatic spread is present, because some patients show regression of metastases. Transitional cell carcinoma arises from the urothelium. The urothelium is present from the calices to the urethra and behaves as a “single unit.” Therefore, when patients develop transitional carcinomas within the bladder, similar tumors may also be present within upper parts of the urinary tract. In patients with bladder cancer, the whole of the urinary tract must always be investigated to exclude the possibility of other tumors (Fig. 4.159). This is currently achieved by performing a dual-phase CT urogram that allows visualization of the renal parenchyma and the collecting system at the same time. In the clinic


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Anatomy_Gray. In the clinic A nephrostomy is a procedure where a tube is placed through the lateral or posterior abdominal wall into the renal cortex to lie within the renal pelvis. The function of this tube is to allow drainage of urine from the renal pelvis through the tube externally (Fig. 4.160). The kidneys are situated on the posterior abdominal wall, and in thin healthy subjects may be only up to 2 to 3 cm from the skin. Access to the kidney is relatively straightforward, because the kidney can be easily visualized under ultrasound guidance. Using local anesthetic, a needle can be placed, under ultrasound direction, through the skin into the renal cortex and into the renal pelvis. A series of wires and tubes can be passed through the needle to position the drainage catheter.


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Anatomy_Gray. The indications for such a procedure are many. In patients with distal ureteric obstruction the back pressure of urine within the ureters and the kidney significantly impairs the function of the kidney. This will produce renal failure and ultimately death. Furthermore, a dilated obstructed system is also susceptible to infection. In many cases, there is not only obstruction producing renal failure but also infected urine within the system. In the clinic Renal transplantation is now a common procedure undertaken in patients with end-stage renal failure. Transplant kidneys are obtained from either living or deceased donors. The living donors are carefully assessed, because harvesting a kidney from a normal healthy individual, even with modern-day medicine, carries a small risk. Deceased kidney donors are brain dead or have suffered cardiac death. The donor kidney is harvested with a small cuff of aortic and venous tissue. The ureter is also harvested.


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Anatomy_Gray. An ideal place to situate the transplant kidney is in the left or the right iliac fossa (Fig. 4.161). A curvilinear incision is made paralleling the iliac crest and pubic symphysis. The external oblique muscle, internal oblique muscle, transversus abdominis muscle, and transversalis fascia are divided. The surgeon identifies the parietal peritoneum but does not enter the peritoneal cavity. The parietal peritoneum is medially retracted to reveal the external iliac artery, external iliac vein, and bladder. In some instances the internal iliac artery of the recipient is mobilized and anastomosed directly as an end-to-end procedure onto the renal artery of the donor kidney. Similarly the internal iliac vein is anastomosed to the donor vein. In the presence of a small aortic cuff of tissue the donor artery is anastomosed to the recipient external iliac artery and similarly for the venous anastomosis. The ureter is easily tunneled obliquely through the bladder wall with a straightforward


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Anatomy_Gray. donor artery is anastomosed to the recipient external iliac artery and similarly for the venous anastomosis. The ureter is easily tunneled obliquely through the bladder wall with a straightforward anastomosis.


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Anatomy_Gray. The left and right iliac fossae are ideal locations for the transplant kidney because a new space can be created without compromise to other structures. The great advantage of this procedure is the proximity to the anterior abdominal wall, which permits easy ultrasound visualization of the kidney and Doppler vascular assessment. Furthermore, in this position biopsies are easily obtained. The extraperitoneal approach enables patients to make a swift recovery. In the clinic Investigation of the urinary tract After an appropriate history and examination of the patient, including a digital rectal examination to assess the prostate in men, special investigations are required.


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Anatomy_Gray. After an appropriate history and examination of the patient, including a digital rectal examination to assess the prostate in men, special investigations are required. Cystoscopy is a technique that allows visualization of the urinary bladder and urethra using an optical system attached to a flexible or rigid tube (cystoscope). Images are displayed on a monitor, as done in other endoscopic studies. Biopsies, bladder stone removal, removal of foreign bodies from the bladder, and bleeding cauterization can be performed during cystoscopy. Cystoscopy is helpful in establishing the causes of macroscopic and microscopic hematuria, assessing bladder and urethral diverticula and fistulas, as well as serving as a tool to investigate patients with voiding problems.


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Anatomy_Gray. An IVU is one of the most important and commonly carried out radiological investigations (Fig. 4.162). The patient is injected with iodinated contrast medium. Most contrast media contain three iodine atoms spaced around a benzene ring. The relatively high atomic number of iodine compared to the atomic number of carbon, hydrogen, and oxygen attenuates the radiation beam. After intravenous injection, contrast media are excreted predominantly by glomerular filtration, although some are secreted by the renal tubules. This allows visualization of the collecting system as well as the ureters and bladder. Ultrasound can be used to assess kidney size and the size of the calices, which may be dilated when obstructed. Although the ureters are poorly visualized using ultrasound, the bladder can be easily seen when full. Ultrasound measurements of bladder volume can be obtained before and after micturition.


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Anatomy_Gray. Nuclear medicine is an extremely useful tool for investigating the urinary tract because radioisotope compounds can be used to estimate renal cell mass and function and assess the parenchyma for renal scarring. These tests are often very useful in children when renal scarring and reflux disease is suspected. In the clinic An abdominal aortic aneurysm is a dilation of the aorta and generally tends to occur in the infrarenal region (the region at or below the renal arteries). As the aorta expands, the risk of rupture increases, and it is now generally accepted that when an aneurysm reaches 5.5 cm or greater an operation will significantly benefit the patient. With the aging population, the number of abdominal aortic aneurysms is increasing. Moreover, with the increasing use of imaging techniques, a number of abdominal aortic aneurysms are identified in asymptomatic patients.


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Anatomy_Gray. For many years the standard treatment for repair was an open operative technique, which involved a large incision from the xiphoid process of the sternum to the symphysis pubis and dissection of the aneurysm. The aneurysm was excised and a tubular woven graft was sewn into place. Recovery may take a number of days, even weeks, and most patients would be placed in the intensive care unit after the operation. Further developments and techniques have led to a new type of procedure being performed to treat abdominal aortic aneurysms—the endovascular graft (Fig. 4.165).


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Anatomy_Gray. Further developments and techniques have led to a new type of procedure being performed to treat abdominal aortic aneurysms—the endovascular graft (Fig. 4.165). The technique involves surgically dissecting the femoral artery below the inguinal ligament. A small incision is made in the femoral artery and the preloaded compressed graft with metal support struts is passed on a large catheter into the abdominal aorta through the femoral artery. Using X-ray for guidance the graft is opened, lining the inside of the aorta. Limb attachments are made to the graft that extend into the common iliac vessels. This bifurcated tube device effectively excludes the abdominal aortic aneurysm. This type of device is not suitable for all patients. Patients who receive this device do not need to go to the intensive care unit. Many patients leave the hospital within 24 to 48 hours. Importantly, this device can be used for patients who were deemed unfit for open surgical repair. In the clinic


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Anatomy_Gray. In the clinic Deep vein thrombosis is a potentially fatal condition where a clot (thrombus) is formed in the deep venous system of the legs and the veins of the pelvis. Virchow described the reasons for thrombus formation as decreased blood flow, abnormality of the constituents of blood, and abnormalities of the vessel wall. Common predisposing factors include hospitalization and surgery, the oral contraceptive pill, smoking, and air travel. Other factors include clotting abnormalities (e.g., protein S and protein C deficiency). The diagnosis of deep vein thrombosis may be difficult to establish, with symptoms including leg swelling and pain and discomfort in the calf. It may also be an incidental finding. In practice, patients with suspected deep vein thrombosis undergo a D-dimer blood test, which measures levels of a fibrin degradation product. If this is positive there is a high association with deep vein thrombosis.


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Anatomy_Gray. The consequences of deep vein thrombosis are twofold. Occasionally the clot may dislodge and pass into the venous system through the right side of the heart and into the main pulmonary arteries. If the clots are of significant size they obstruct blood flow to the lung and may produce instantaneous death. Secondary complications include destruction of the normal valvular system in the legs, which may lead to venous incompetency and chronic leg swelling with ulceration. The treatment for deep vein thrombosis is prevention. In order to prevent deep vein thrombosis, patients are optimized by removing all potential risk factors. Subcutaneous heparin may be injected and the patient wears compression stockings to prevent venous stasis while in the hospital.


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Anatomy_Gray. In certain situations it is not possible to optimize the patient with prophylactic treatment, and it may be necessary to insert a filter into the inferior vena cava that traps any large clots. It may be removed after the risk period has ended. In the clinic From a clinical perspective, retroperitoneal lymph nodes are arranged in two groups. The pre-aortic lymph node group drains lymph from the embryological midline structures, such as the liver, bowel, and pancreas. The para-aortic lymph node group (the lateral aortic or lumbar nodes), on either side of the aorta, drain lymph from bilateral structures, such as the kidneys and adrenal glands. Organs embryologically derived from the posterior abdominal wall also drain lymph to these nodes. These organs include the ovaries and the testes (importantly, the testes do not drain lymph to the inguinal regions).


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Anatomy_Gray. In general, lymphatic drainage follows standard predictable routes; however, in the presence of disease, alternate routes of lymphatic drainage will occur. There are a number of causes for enlarged retroperitoneal lymph nodes. In the adult, massively enlarged lymph nodes are a feature of lymphoma, and smaller lymph node enlargement is observed in the presence of infection and metastatic malignant spread of disease (e.g., colon cancer). The treatment for malignant lymph node disease is based upon a number of factors, including the site of the primary tumor (e.g., bowel) and its histological cell type. Normally, the primary tumor is surgically removed and the lymph node spread and metastatic organ spread (e.g., to the liver and the lungs) are often treated with chemotherapy and radiotherapy. In certain instances it may be considered appropriate to resect the lymph nodes in the retroperitoneum (e.g., for testicular cancer).


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Anatomy_Gray. The surgical approach to retroperitoneal lymph node resection involves a lateral paramedian incision in the midclavicular line. The three layers of the anterolateral abdominal wall (external oblique, internal oblique, and transversus abdominis) are opened and the transversalis fascia is divided. The next structure the surgeon sees is the parietal peritoneum. Instead of entering the parietal peritoneum, which is standard procedure for most intraabdominal operations, the surgeon gently pushes the parietal peritoneum toward the midline, which moves the intraabdominal contents and allows a clear view of the retroperitoneal structures. On the left, the para-aortic lymph node group is easily demonstrated, with a clear view of the abdominal aorta and kidney. On the right the inferior vena cava is demonstrated and has to be retracted to access the right para-aortic lymph node chain.


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Anatomy_Gray. The procedure of retroperitoneal lymph node dissection is extremely well tolerated and lacks the problems of entering the peritoneal cavity (e.g., paralytic ileus). Unfortunately, a complication of a vertical incision in the midclavicular line is division of the segmental nerve supply to the rectus abdominis muscle. This produces muscle atrophy and asymmetrical proportions of the anterior abdominal wall. A 45-year-old man had mild epigastric pain, and a diagnosis of esophageal reflux was made. He was given appropriate medication, which worked well. However, at the time of the initial consultation, the family practitioner requested a chest radiograph, which demonstrated a prominent hump on the left side of the diaphragm and old rib fractures. The patient was recalled for further questioning.


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Anatomy_Gray. The patient was recalled for further questioning. He was extremely pleased with the treatment he had been given for his gastroesophageal reflux, but was concerned about being recalled for further history and examination. During the interview, he revealed that he had previously been involved in a motorcycle accident and had undergone a laparotomy for a “rupture.” The patient did not recall what operation was performed, but was assured at the time that the operation was a great success. The patient is likely to have undergone a splenectomy. In any patient who has had severe blunt abdominal trauma (such as that caused by a motorcycle accident), lower left-sided rib fractures are an extremely important sign of appreciable trauma.


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Anatomy_Gray. In any patient who has had severe blunt abdominal trauma (such as that caused by a motorcycle accident), lower left-sided rib fractures are an extremely important sign of appreciable trauma. A review of the patient’s old notes revealed that at the time of the injury the spleen was removed surgically, but it was not appreciated that there was a small rupture of the dome of the left hemidiaphragm. The patient gradually developed a hernia through which bowel could enter, producing the “hump” on the diaphragm seen on the chest radiograph. Because this injury occurred many years ago and the patient has been asymptomatic, it is unlikely that the patient will come to any harm and was discharged.


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Anatomy_Gray. Because this injury occurred many years ago and the patient has been asymptomatic, it is unlikely that the patient will come to any harm and was discharged. A medical student was asked to inspect the abdomen of two patients. On the first patient he noted irregular veins radiating from the umbilicus. On the second patient he noted irregular veins, coursing in a caudal to cranial direction, over the anterior abdominal wall from the groin to the chest. He was asked to explain his findings and determine the significance of these features.


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Anatomy_Gray. In the first patient the veins were draining radially away from the periumbilical region. In normal individuals, enlarged veins do not radiate from the umbilicus. In patients with portal hypertension the portal venous pressure is increased as a result of hepatic disease. Small collateral veins develop at and around the obliterated umbilical vein. These veins pass through the umbilicus and drain onto the anterior abdominal wall, forming a portosystemic anastomosis. The eventual diagnosis for this patient was cirrhosis of the liver.


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Anatomy_Gray. The finding of veins draining in a caudocranial direction on the anterior abdominal wall in the second patient is not typical for veins on the anterior abdominal wall. When veins are so prominent, it usually implies that there is an obstruction to the normal route of venous drainage and an alternative route has been taken. Typically, blood from the lower limbs and the retroperitoneal organs drains into the inferior vena cava and from here to the right atrium of the heart. This patient had a chronic thrombosis of the inferior vena cava, preventing blood from returning to the heart by the “usual” route.