Anatomy_Gray

Anatomy_Gray. Together with small glands positioned along the length of the spongy urethra, the bulbo-urethral glands contribute to lubrication of the urethra and the pre-ejaculatory emission from the penis. The reproductive tract in women is contained mainly in the pelvic cavity and perineum, although during pregnancy, the uterus expands into the abdominal cavity. Major components of the system consist of: an ovary on each side, and a uterus, vagina, and clitoris in the midline (Fig. 5.50). In addition, a pair of accessory glands (the greater vestibular glands) are associated with the tract. Like the testes in men, the ovaries develop high on the posterior abdominal wall and then descend before birth, bringing with them their vessels, lymphatics, and nerves. Unlike the testes, the ovaries do not migrate through the inguinal canal into the perineum, but stop short and assume a position on the lateral wall of the pelvic cavity (Fig. 5.51).


Anatomy_Gray

Anatomy_Gray. The ovaries are the sites of egg production (oogenesis). Mature eggs are ovulated into the peritoneal cavity and normally directed into the adjacent openings of the uterine tubes by cilia on the ends of the uterine tubes. The ovaries lie adjacent to the lateral pelvic wall just inferior to the pelvic inlet. Each of the two almond-shaped ovaries is about 3 cm long and is suspended by a mesentery (the mesovarium) that is a posterior extension of the broad ligament. The uterus is a thick-walled muscular organ in the midline between the bladder and rectum (see Fig. 5.51). It consists of a body and a cervix, and inferiorly it joins the vagina (Fig. 5.53). Superiorly, uterine tubes project laterally from the uterus and open into the peritoneal cavity immediately adjacent to the ovaries.


Anatomy_Gray

Anatomy_Gray. The body of the uterus is flattened anteroposteriorly and, above the level of origin of the uterine tubes (Fig. 5.53), has a rounded superior end (fundus of the uterus). The cavity of the body of the uterus is a narrow slit, when viewed laterally, and is shaped like an inverted triangle, when viewed anteriorly. Each of the superior corners of the cavity is continuous with the lumen of a uterine tube; the inferior corner is continuous with the central canal of the cervix. Implantation of the blastocyst normally occurs in the body of the uterus. During pregnancy, the uterus dramatically expands superiorly into the abdominal cavity.


Anatomy_Gray

Anatomy_Gray. Implantation of the blastocyst normally occurs in the body of the uterus. During pregnancy, the uterus dramatically expands superiorly into the abdominal cavity. The uterine tubes extend from each side of the superior end of the body of the uterus to the lateral pelvic wall and are enclosed within the upper margins of the mesosalpinx portions of the broad ligaments (see p. 477). Because the ovaries are suspended from the posterior aspect of the broad ligaments, the uterine tubes pass superiorly over, and terminate laterally to, the ovaries.


Anatomy_Gray

Anatomy_Gray. Each uterine tube has an expanded trumpet-shaped end (the infundibulum), which curves around the superolateral pole of the related ovary (Fig. 5.54). The margin of the infundibulum is rimmed with small finger-like projections termed fimbriae. The lumen of the uterine tube opens into the peritoneal cavity at the narrowed end of the infundibulum. Medial to the infundibulum, the tube expands to form the ampulla and then narrows to form the isthmus, before joining with the body of the uterus. The fimbriated infundibulum facilitates the collection of ovulated eggs from the ovary. Fertilization normally occurs in the ampulla.


Anatomy_Gray

Anatomy_Gray. The fimbriated infundibulum facilitates the collection of ovulated eggs from the ovary. Fertilization normally occurs in the ampulla. The cervix forms the inferior part of the uterus and is shaped like a short, broad cylinder with a narrow central channel. The body of the uterus normally arches forward (anteflexed on the cervix) over the superior surface of the emptied bladder (Fig. 5.55A). In addition, the cervix is angled forward (anteverted) on the vagina so that the inferior end of the cervix projects into the upper anterior aspect of the vagina. Because the end of the cervix is dome shaped, it bulges into the vagina, and a gutter, or fornix, is formed around the margin of the cervix where it joins the vaginal wall (Fig. 5.55B). The tubular central canal of the cervix opens, below, as the external os, into the vaginal cavity and, above, as the internal os, into the uterine cavity.


Anatomy_Gray

Anatomy_Gray. The vagina is the copulatory organ in women. It is a distensible fibromuscular tube that extends from the perineum through the pelvic floor and into the pelvic cavity (Fig. 5.57A). The internal end of the canal is enlarged to form a region called the vaginal vault. The anterior wall of the vagina is related to the base of the bladder and to the urethra; in fact, the urethra is embedded in, or fused to, the anterior vaginal wall. Posteriorly, the vagina is related principally to the rectum. Inferiorly, the vagina opens into the vestibule of the perineum immediately posterior to the external opening of the urethra. From its external opening (the introitus), the vagina courses posterosuperiorly through the perineal membrane and into the pelvic cavity, where it is attached by its anterior wall to the circular margin of the cervix.


Anatomy_Gray

Anatomy_Gray. The vaginal fornix is the recess formed between the margin of the cervix and the vaginal wall. Based on position, the fornix is subdivided into a posterior fornix, an anterior fornix, and two lateral fornices (Fig. 5.57A and see Fig. 5.55). The vaginal canal is normally collapsed so that the anterior wall is in contact with the posterior wall. By using a speculum to open the vaginal canal, a physician can see the domed inferior end of the cervix, the vaginal fornices, and the external os of the cervical canal in a patient (Fig. 5.57B). During intercourse, semen is deposited in the vaginal vault. Spermatozoa make their way into the external os of the cervical canal, pass through the cervical canal into the uterine cavity, and then continue through the uterine cavity into the uterine tubes where fertilization normally occurs in the ampulla.


Anatomy_Gray

Anatomy_Gray. Fascia in the pelvic cavity lines the pelvic walls, surrounds the bases of the pelvic viscera, and forms sheaths around blood vessels and nerves that course medially from the pelvic walls to reach the viscera in the midline. This pelvic fascia is a continuation of the extraperitoneal connective tissue layer found in the abdomen.


Anatomy_Gray

Anatomy_Gray. In women, a rectovaginal septum separates the posterior surface of the vagina from the rectum (Fig. 5.58A). Condensations of fascia form ligaments that extend from the cervix to the anterior (pubocervical ligament), lateral (transverse cervical or cardinal ligament), and posterior (uterosacral ligament) pelvic walls (Fig. 5.58A). These ligaments, together with the perineal membrane, the levator ani muscles, and the perineal body, are thought to stabilize the uterus in the pelvic cavity. The most important of these ligaments are the transverse cervical or cardinal ligaments, which extend laterally from each side of the cervix and vaginal vault to the related pelvic wall.


Anatomy_Gray

Anatomy_Gray. In men, a condensation of fascia around the anterior and lateral region of the prostate (prostatic fascia) contains and surrounds the prostatic plexus of veins and is continuous posteriorly with the rectovesical septum, which separates the posterior surface of the prostate and base of the bladder from the rectum (Fig. 5.58B). The peritoneum of the pelvis is continuous at the pelvic inlet with the peritoneum of the abdomen. In the pelvis, the peritoneum drapes over the pelvic viscera in the midline, forming: pouches between adjacent viscera, and folds and ligaments between viscera and pelvic walls.


Anatomy_Gray

Anatomy_Gray. Anteriorly, median and medial umbilical folds of peritoneum cover the embryological remnants of the urachus and umbilical arteries, respectively (Fig. 5.59). These folds ascend out of the pelvis and onto the anterior abdominal wall. Posteriorly, peritoneum drapes over the anterior and lateral aspects of the upper third of the rectum, but only the anterior surface of the middle third of the rectum is covered by peritoneum; the lower third of the rectum is not covered at all.


Anatomy_Gray

Anatomy_Gray. In women, the uterus lies between the bladder and rectum, and the uterine tubes extend from the superior aspect of the uterus to the lateral pelvic walls (Fig. 5.59A). As a consequence, a shallow vesico-uterine pouch occurs anteriorly, between the bladder and uterus, and a deep recto-uterine pouch (pouch of Douglas) occurs posteriorly, between the uterus and rectum. In addition, a large fold of peritoneum (the broad ligament), with a uterine tube enclosed in its superior margin and an ovary attached posteriorly, is located on each side of the uterus and extends to the lateral pelvic walls.


Anatomy_Gray

Anatomy_Gray. In the midline, the peritoneum descends over the posterior surface of the uterus and cervix and onto the vaginal wall adjacent to the posterior vaginal fornix. It then reflects onto the anterior and lateral walls of the rectum. The deep pouch of peritoneum formed between the anterior surface of the rectum and posterior surfaces of the uterus, cervix, and vagina is the recto-uterine pouch. A sharp sickle-shaped ridge of peritoneum (recto-uterine fold) occurs on each side near the base of the recto-uterine pouch. The recto-uterine folds overlie the uterosacral ligaments, which are condensations of pelvic fascia that extend from the cervix to the posterolateral pelvic walls.


Anatomy_Gray

Anatomy_Gray. The broad ligament is a sheet-like fold of peritoneum, oriented in the coronal plane that runs from the lateral pelvic wall to the uterus, and encloses the uterine tube in its superior margin and suspends the ovary from its posterior aspect (Fig. 5.59A). The uterine arteries cross the ureters at the base of the broad ligaments, and the ligament of the ovary and round ligament of the uterus are enclosed within the parts of the broad ligament related to the ovary and uterus, respectively. The broad ligament has three parts: the mesometrium, the largest part of the broad ligament, which extends from the lateral pelvic walls to the body of the uterus; the mesosalpinx, the most superior part of the broad ligament, which suspends the uterine tube in the pelvic cavity; and the mesovarium, a posterior extension of the broad ligament, which attaches to the ovary.


Anatomy_Gray

Anatomy_Gray. The peritoneum of the mesovarium is continuous with the ovarian surface (germinal) epithelium (see Fig. 5.59A insert). The ovaries are positioned with their long axis in the vertical plane. The ovarian vessels, nerves, and lymphatics enter the superior pole of the ovary from a lateral position and are covered by another raised fold of peritoneum, which with the structures it contains forms the suspensory ligament of the ovary (infundibulopelvic ligament).


Anatomy_Gray

Anatomy_Gray. The inferior pole of the ovary is attached to a fibromuscular band of tissue (the ligament of the ovary), which courses medially in the margin of the mesovarium to the uterus and then continues anterolaterally as the round ligament of the uterus (Fig. 5.59A). The round ligament of the uterus passes over the pelvic inlet to reach the deep inguinal ring and then courses through the inguinal canal to end in connective tissue related to the labium majus in the perineum. Both the ligament of the ovary and the round ligament of the uterus are remnants of the gubernaculum, which attaches the gonad to the labioscrotal swellings in the embryo. In men, the visceral peritoneum drapes over the top of the bladder onto the superior poles of the seminal vesicles and then reflects onto the anterior and lateral surfaces of the rectum (Fig. 5.59B). A rectovesical pouch occurs between the bladder and rectum.


Anatomy_Gray

Anatomy_Gray. The sacral and coccygeal plexuses are situated on the posterolateral wall of the pelvic cavity and generally occur in the plane between the muscles and blood vessels. They are formed by the ventral rami of S1 to Co, with a significant contribution from L4 and L5, which enter the pelvis from the lumbar plexus (Fig. 5.60). Nerves from these mainly somatic plexuses contribute to the innervation of the lower limb and muscles of the pelvis and perineum. Cutaneous branches supply skin over the medial side of the foot, the posterior aspect of the lower limb, and most of the perineum.


Anatomy_Gray

Anatomy_Gray. The sacral plexus on each side is formed by the anterior rami of S1 to S4, and the lumbosacral trunk (L4 and L5) (Fig. 5.61). The plexus is formed in relation to the anterior surface of the piriformis muscle, which is part of the posterolateral pelvic wall. Sacral contributions to the plexus pass out of the anterior sacral foramina and course laterally and inferiorly on the pelvic wall. The lumbosacral trunk, consisting of part of the anterior ramus of L4 and all of the anterior ramus of L5, courses vertically into the pelvic cavity from the abdomen by passing immediately anterior to the sacro-iliac joint.


Anatomy_Gray

Anatomy_Gray. Gray rami communicantes from ganglia of the sympathetic trunk connect with each of the anterior rami and carry postganglionic sympathetic fibers destined for the periphery to the somatic nerves (Fig. 5.62). In addition, special visceral nerves (pelvic splanchnic nerves) originating from S2 to S4 deliver preganglionic parasympathetic fibers to the pelvic part of the prevertebral plexus (Figs. 5.60 and 5.61). Each anterior ramus has ventral and dorsal divisions that combine with similar divisions from other levels to form terminal nerves (Fig. 5.61). The anterior ramus of S4 has only a ventral division. Branches of the sacral plexus include the sciatic nerve and gluteal nerves, which are major nerves of the lower limb, and the pudendal nerve, which is the nerve of the perineum (Table 5.4). Numerous smaller branches supply the pelvic wall, floor, and lower limb.


Anatomy_Gray

Anatomy_Gray. Most nerves originating from the sacral plexus leave the pelvic cavity by passing through the greater sciatic foramen inferior to the piriformis muscle, and enter the gluteal region of the lower limb. Other nerves leave the pelvic cavity using different routes; a few nerves do not leave the pelvic cavity and course directly into the muscles in the pelvic cavity. Finally, two nerves that leave the pelvic cavity through the greater sciatic foramen loop around the ischial spine and sacrospinous ligament and pass medially through the lesser sciatic foramen to supply structures in the perineum and lateral pelvic wall.


Anatomy_Gray

Anatomy_Gray. Sciatic nerve. The sciatic nerve is the largest nerve of the body and carries contributions from L4 to S3 (Figs. 5.60 and 5.61). It: forms on the anterior surface of the piriformis muscle and leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis; passes through the gluteal region into the thigh, where it divides into its two major branches, the common fibular nerve (common peroneal nerve) and the tibial nerve—dorsal divisions of L4, L5, S1, and S2 are carried in the common fibular part of the nerve and the ventral divisions of L4, L5, S1, S2, and S3 are carried in the tibial part; innervates muscles in the posterior compartment of the thigh and muscles in the leg and foot; and carries sensory fibers from the skin of the foot and lateral leg.


Anatomy_Gray

Anatomy_Gray. Pudendal nerve. The pudendal nerve forms anteriorly to the lower part of the piriformis muscle from ventral divisions of S2 to S4 (Figs. 5.60 and 5.61). It: leaves the pelvic cavity through the greater sciatic foramen, inferior to the piriformis muscle, and enters the gluteal region; courses into the perineum by immediately passing around the sacrospinous ligament, where the ligament joins the ischial spine, and through the lesser sciatic foramen (this course takes the nerve out of the pelvic cavity, around the peripheral attachment of the pelvic floor, and into the perineum); is accompanied throughout its course by the internal pudendal vessels; and innervates skin and skeletal muscles of the perineum, including the external anal and external urethral sphincters.


Anatomy_Gray

Anatomy_Gray. Other branches of the sacral plexus. Other branches of the sacral plexus include: motor branches to muscles of the gluteal region, pelvic wall, and pelvic floor (superior and inferior gluteal nerves, nerve to obturator internus and superior gemellus, nerve to quadratus femoris and inferior gemellus, nerve to piriformis, nerves to levator ani); and sensory nerves to skin over the inferior gluteal region and posterior aspects of the thigh and upper leg (perforating cutaneous nerve and posterior cutaneous nerve of the thigh) (Figs. 5.60 and 5.61). The superior gluteal nerve, formed by branches from the dorsal divisions of L4 to S1, leaves the pelvic cavity through the greater sciatic foramen superior to the piriformis muscle and supplies muscles in the gluteal region—gluteus medius, gluteus minimus, and tensor fasciae latae (tensor of fascia lata) muscles.


Anatomy_Gray

Anatomy_Gray. The inferior gluteal nerve, formed by branches from the dorsal divisions of L5 to S2, leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle and supplies the gluteus maximus, the largest muscle in the gluteal region. Both superior and inferior gluteal nerves are accompanied by corresponding arteries. The nerve to the obturator internus and the associated superior gemellus muscle originates from the ventral divisions of L5 to S2 and leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle. Like the pudendal nerve, it passes around the ischial spine and through the lesser sciatic foramen to enter the perineum and supply the obturator internus muscle from the medial side of the muscle, inferior to the attachment of the levator ani muscle.


Anatomy_Gray

Anatomy_Gray. The nerve to the quadratus femoris muscle and the inferior gemellus muscle, and the posterior cutaneous nerve of the thigh (posterior femoral cutaneous nerve) also leave the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle and course to muscles and skin, respectively, in the lower limb. Unlike most of the other nerves originating from the sacral plexus, which leave the pelvic cavity through the greater sciatic foramen either above or below the piriformis muscle, the perforating cutaneous nerve leaves the pelvic cavity by penetrating directly through the sacrotuberous ligament and then courses to skin over the inferior aspect of the buttocks. The nerve to the piriformis and a number of small nerves to the levator ani and coccygeus muscles originate from the sacral plexus and pass directly into their target muscles without leaving the pelvic cavity.


Anatomy_Gray

Anatomy_Gray. The obturator nerve (L2 to L4) is a branch of the lumbar plexus. It passes inferiorly along the posterior abdominal wall within the psoas muscle, emerges from the medial surface of the psoas, passes posteriorly to the common iliac artery and medially to the internal iliac artery at the pelvic inlet, and then courses along the lateral pelvic wall. It leaves the pelvic cavity by traveling through the obturator canal and supplies the adductor region of the thigh. The small coccygeal plexus has a minor contribution from S4 and is formed mainly by the anterior rami of S5 and Co, which originate inferiorly to the pelvic floor. They penetrate the coccygeus muscle to enter the pelvic cavity and join with the anterior ramus of S4 to form a single trunk, from which small anococcygeal nerves originate (Table 5.4). These nerves penetrate the muscle and the overlying sacrospinous and sacrotuberous ligaments and pass superficially to innervate skin in the anal triangle of the perineum.


Anatomy_Gray

Anatomy_Gray. The paravertebral part of the visceral nervous system is represented in the pelvis by the inferior ends of the sympathetic trunks (Fig. 5.63A). Each trunk enters the pelvic cavity from the abdomen by passing over the ala of the sacrum medially to the lumbosacral trunks and posteriorly to the iliac vessels. The trunks course inferiorly along the anterior surface of the sacrum, where they are positioned medially to the anterior sacral foramina. Four ganglia occur along each trunk. Anteriorly to the coccyx, the two trunks join to form a single small terminal ganglion (the ganglion impar). The principal function of the sympathetic trunks in the pelvis is to deliver postganglionic sympathetic fibers to the anterior rami of sacral nerves for distribution to the periphery, mainly to parts of the lower limb and perineum. This is accomplished by gray rami communicantes, which connect the trunks to the sacral anterior rami.


Anatomy_Gray

Anatomy_Gray. In addition to gray rami communicantes, other branches (the sacral splanchnic nerves) join and contribute to the pelvic part of the prevertebral plexus associated with innervating pelvic viscera (Fig. 5.63A). Pelvic extensions of the prevertebral plexus The pelvic parts of the prevertebral plexus carry sympathetic, parasympathetic, and visceral afferent fibers (Fig. 5.63A). Pelvic parts of the plexus are associated with innervating pelvic viscera and erectile tissues of the perineum. The prevertebral plexus enters the pelvis as two hypogastric nerves, one on each side, that cross the pelvic inlet medially to the internal iliac vessels (Fig. 5.63A). The hypogastric nerves are formed by the separation of the fibers in the superior hypogastric plexus, into right and left bundles. The superior hypogastric plexus is situated anterior to vertebra LV between the promontory of the sacrum and the bifurcation of the aorta.


Anatomy_Gray

Anatomy_Gray. When the hypogastric nerves are joined by pelvic splanchnic nerves carrying preganglionic parasympathetic fibers from S2 to S4, the pelvic plexuses (inferior hypogastric plexuses) are formed (Fig. 5.63). The inferior hypogastric plexuses, one on each side, course in an inferior direction around the pelvic walls, medially to major vessels and somatic nerves. They give origin to the following subsidiary plexuses, which innervate the pelvic viscera: the rectal plexus, the uterovaginal plexus, the prostatic plexus, and the vesical plexus. Terminal branches of the inferior hypogastric plexuses penetrate and pass through the deep perineal pouch and innervate erectile tissues of the penis and the clitoris in the perineum (Fig. 5.63B). In men, these nerves, called cavernous nerves, are extensions of the prostatic plexus. The pattern of distribution of similar nerves in women is not entirely clear, but they are likely extensions of the uterovaginal plexus.


Anatomy_Gray

Anatomy_Gray. Sympathetic fibers enter the inferior hypogastric plexuses from the hypogastric nerves and from branches (sacral splanchnic nerves) of the upper sacral parts of the sympathetic trunks (Fig. 5.63A). Ultimately, these nerves are derived from preganglionic fibers that leave the spinal cord in the anterior roots, mainly of T10 to L2. These fibers: innervate blood vessels, cause contraction of smooth muscle in the internal urethral sphincter in men and the internal anal sphincters in both men and women, cause smooth muscle contraction associated with the reproductive tract and with the accessory glands of the reproductive system, and are important in moving secretions from the epididymis and associated glands into the urethra to form semen during ejaculation.


Anatomy_Gray

Anatomy_Gray. Parasympathetic fibers enter the pelvic plexus in pelvic splanchnic nerves that originate from spinal cord levels S2 to S4 (Fig. 5.63A). They: are generally vasodilatory, stimulate bladder contraction, stimulate erection, and modulate activity of the enteric nervous system of the colon distal to the left colic flexure (in addition to pelvic viscera, some of the fibers from the pelvic plexus course superiorly in the prevertebral plexus, or as separate nerves, and pass into the inferior mesenteric plexus of the abdomen). Visceral afferent fibers follow the course of the sympathetic and parasympathetic fibers to the spinal cord. Afferent fibers that enter the cord in lower thoracic levels and lumbar levels with sympathetic fibers generally carry pain; however, pain fibers from the cervix and some pain fibers from the bladder and urethra may accompany parasympathetic nerves to sacral levels of the spinal cord.


Anatomy_Gray

Anatomy_Gray. The major artery of the pelvis and perineum is the internal iliac artery on each side (Fig. 5.64). In addition to providing a blood supply to most of the pelvic viscera, pelvic walls and floor, and structures in the perineum, including erectile tissues of the clitoris and the penis, this artery gives rise to branches that follow nerves into the gluteal region of the lower limb. Other vessels that originate in the abdomen and contribute to the supply of pelvic structures include the median sacral artery and, in women, the ovarian arteries.


Anatomy_Gray

Anatomy_Gray. The internal iliac artery originates from the common iliac artery on each side, approximately at the level of the intervertebral disc between LV and SI, and lies anteromedial to the sacro-iliac joint (Fig. 5.64). The vessel courses inferiorly over the pelvic inlet and then divides into anterior and posterior trunks at the level of the superior border of the greater sciatic foramen. Branches from the posterior trunk contribute to the supply of the lower posterior abdominal wall, the posterior pelvic wall, and the gluteal region. Branches from the anterior trunk supply the pelvic viscera, the perineum, the gluteal region, the adductor region of the thigh, and, in the fetus, the placenta. Branches of the posterior trunk of the internal iliac artery are the iliolumbar artery, the lateral sacral artery, and the superior gluteal artery (Fig. 5.64).


Anatomy_Gray

Anatomy_Gray. Branches of the posterior trunk of the internal iliac artery are the iliolumbar artery, the lateral sacral artery, and the superior gluteal artery (Fig. 5.64). The iliolumbar artery ascends laterally back out of the pelvic inlet and divides into a lumbar branch and an iliac branch. The lumbar branch contributes to the supply of the posterior abdominal wall, psoas and quadratus lumborum muscles, and cauda equina, via a small spinal branch that passes through the intervertebral foramen between LV and SI. The iliac branch passes laterally into the iliac fossa to supply muscle and bone. The lateral sacral arteries, usually two, originate from the posterior division of the internal iliac artery and course medially and inferiorly along the posterior pelvic wall. They give rise to branches that pass into the anterior sacral foramina to supply related bone and soft tissues, structures in the vertebral (sacral) canal, and skin and muscle posterior to the sacrum.


Anatomy_Gray

Anatomy_Gray. The superior gluteal artery is the largest branch of the internal iliac artery and is the terminal continuation of the posterior trunk. It courses posteriorly, usually passing between the lumbosacral trunk and anterior ramus of S1, to leave the pelvic cavity through the greater sciatic foramen above the piriformis muscle and enter the gluteal region of the lower limb. This vessel makes a substantial contribution to the blood supply of muscles and skin in the gluteal region and also supplies branches to adjacent muscles and bones of the pelvic walls. Branches of the anterior trunk of the internal iliac artery include the superior vesical artery, the umbilical artery, the inferior vesical artery, the middle rectal artery, the uterine artery, the vaginal artery, the obturator artery, the internal pudendal artery, and the inferior gluteal artery (Fig. 5.65).


Anatomy_Gray

Anatomy_Gray. The first branch of the anterior trunk is the umbilical artery, which gives origin to the superior vesical artery and then travels forward just inferior to the margin of the pelvic inlet. Anteriorly, the vessel leaves the pelvic cavity and ascends on the internal aspect of the anterior abdominal wall to reach the umbilicus. In the fetus, the umbilical artery is large and carries blood from the fetus to the placenta. After birth, the vessel closes distally to the origin of the superior vesical artery and eventually becomes a solid fibrous cord. On the anterior abdominal wall, the cord raises a fold of peritoneum termed the medial umbilical fold. The fibrous remnant of the umbilical artery itself is the medial umbilical ligament.


Anatomy_Gray

Anatomy_Gray. The superior vesical artery normally originates from the root of the umbilical artery and courses medially and inferiorly to supply the superior aspect of the bladder and distal parts of the ureter. In men, it also may give rise to an artery that supplies the ductus deferens. The inferior vesical artery occurs in men and supplies branches to the bladder, ureter, seminal vesicle, and prostate. The vaginal artery in women is the equivalent of the inferior vesical artery in men and, descending to the vagina, supplies branches to the vagina and to adjacent parts of the bladder and rectum. The vaginal artery and uterine artery may originate together as a common branch from the anterior trunk, or the vaginal artery may arise independently.


Anatomy_Gray

Anatomy_Gray. The middle rectal artery courses medially to supply the rectum. The vessel anastomoses with the superior rectal artery, which originates from the inferior mesenteric artery in the abdomen, and the inferior rectal artery, which originates from the internal pudendal artery in the perineum. The obturator artery courses anteriorly along the pelvic wall and leaves the pelvic cavity via the obturator canal. Together with the obturator nerve, above, and obturator vein, below, it enters and supplies the adductor region of the thigh.


Anatomy_Gray

Anatomy_Gray. The internal pudendal artery courses inferiorly from its origin in the anterior trunk and leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle. In association with the pudendal nerve on its medial side, the vessel passes laterally to the ischial spine and then through the lesser sciatic foramen to enter the perineum. The internal pudendal artery is the main artery of the perineum. Among the structures it supplies are the erectile tissues of the clitoris and the penis. The inferior gluteal artery is a large terminal branch of the anterior trunk of the internal iliac artery. It passes between the anterior rami S1 and S2 or S2 and S3 of the sacral plexus and leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle. It enters and contributes to the blood supply of the gluteal region and anastomoses with a network of vessels around the hip joint.


Anatomy_Gray

Anatomy_Gray. The uterine artery in women courses medially and anteriorly in the base of the broad ligament to reach the cervix (Figs. 5.65B and 5.66). Along its course, the vessel crosses the ureter and passes superiorly to the lateral vaginal fornix. Once the vessel reaches the cervix, it ascends along the lateral margin of the uterus to reach the uterine tube, where it curves laterally and anastomoses with the ovarian artery. The uterine artery is the major blood supply to the uterus and enlarges significantly during pregnancy. Through anastomoses with other arteries, the vessel contributes to the blood supply of the ovary and vagina as well.


Anatomy_Gray

Anatomy_Gray. In women, the gonadal (ovarian) vessels originate from the abdominal aorta and then descend to cross the pelvic inlet and supply the ovaries. They anastomose with terminal parts of the uterine arteries (Fig. 5.66). On each side, the vessels travel in the suspensory ligament of the ovary (the infundibulopelvic ligament) as they cross the pelvic inlet to the ovary. Branches pass through the mesovarium to reach the ovary and through the mesometrium of the broad ligament to anastomose with the uterine artery. The ovarian arteries enlarge significantly during pregnancy to augment the uterine blood supply.


Anatomy_Gray

Anatomy_Gray. The median sacral artery (Figs. 5.65A and 5.66) originates from the posterior surface of the aorta just superior to the aortic bifurcation at vertebral level LIV in the abdomen. It descends in the midline, crosses the pelvic inlet, and then courses along the anterior surface of the sacrum and coccyx. It gives rise to the last pair of lumbar arteries and to branches that anastomose with the iliolumbar and lateral sacral arteries. Pelvic veins follow the course of all branches of the internal iliac artery except for the umbilical artery and the iliolumbar artery (Fig. 5.67A). On each side, the veins drain into internal iliac veins, which leave the pelvic cavity to join common iliac veins situated just superior and lateral to the pelvic inlet.


Anatomy_Gray

Anatomy_Gray. Within the pelvic cavity, extensive interconnected venous plexuses are associated with the surfaces of the viscera (bladder, rectum, prostate, uterus, and vagina). Together, these plexuses form the pelvic plexus of veins. The part of the venous plexus surrounding the rectum and anal canal drains via superior rectal veins (tributaries of inferior mesenteric veins) into the hepatic portal system, and via middle and inferior rectal veins into the caval system. This pelvic plexus is an important portacaval shunt when the hepatic portal system is blocked (Fig. 5.67B).


Anatomy_Gray

Anatomy_Gray. The inferior part of the rectal plexus around the anal canal has two parts, an internal and an external. The internal rectal plexus is in connective tissue between the internal anal sphincter and the epithelium lining the canal. This plexus connects superiorly with longitudinally arranged branches of the superior rectal vein that lie one in each anal column. When enlarged, these branches form varices or internal hemorrhoids, which originate above the pectinate line and are covered by colonic mucosa. The external rectal plexus circles the external anal sphincter and is subcutaneous. Enlargement of vessels in the external rectal plexus results in external hemorrhoids.


Anatomy_Gray

Anatomy_Gray. The single deep dorsal vein that drains erectile tissues of the clitoris and the penis does not follow branches of the internal pudendal artery into the pelvic cavity. Instead, this vein passes directly into the pelvic cavity through a gap formed between the arcuate pubic ligament and the anterior margin of the perineal membrane. The vein joins the prostatic plexus of veins in men and the vesical (bladder) plexus of veins in women. (Superficial veins that drain the skin of the penis and corresponding regions of the clitoris drain into the external pudendal veins, which are tributaries of the great saphenous vein in the thigh.) In addition to tributaries of the internal iliac vein, median sacral veins and ovarian veins parallel the courses of the median sacral artery and ovarian artery, respectively, and leave the pelvic cavity to join veins in the abdomen:


Anatomy_Gray

Anatomy_Gray. The median sacral veins coalesce to form a single vein that joins either the left common iliac vein or the junction of the two common iliac veins to form the inferior vena cava. The ovarian veins follow the course of the corresponding arteries; on the left, they join the left renal vein and, on the right, they join the inferior vena cava in the abdomen. Lymphatics from most pelvic viscera drain mainly into lymph nodes distributed along the internal iliac and external iliac arteries and their associated branches (Fig. 5.68), which drain into nodes associated with the common iliac arteries and then into the lateral aortic or lumbar nodes associated with the lateral surfaces of the abdominal aorta. In turn, these lateral aortic or lumbar nodes drain into the lumbar trunks, which continue to the origin of the thoracic duct at approximately vertebral level TXII.


Anatomy_Gray

Anatomy_Gray. Lymphatics from the ovaries and related parts of the uterus and uterine tubes leave the pelvic cavity superiorly and drain, via vessels that accompany the ovarian arteries, directly into lateral aortic or lumbar nodes and, in some cases, into the pre-aortic nodes on the anterior surface of the aorta. In addition to draining pelvic viscera, nodes along the internal iliac artery also receive drainage from the gluteal region of the lower limb and from deep areas of the perineum. The perineum is a diamond-shaped region positioned inferiorly to the pelvic floor between the thighs. Its peripheral boundary is the pelvic outlet; its ceiling is the pelvic diaphragm (the levator ani and coccygeus muscles); and its narrow lateral walls are formed by the walls of the pelvic cavity below the attachment of the levator ani muscle (Fig. 5.69A). The perineum is divided into an anterior urogenital triangle and a posterior anal triangle.


Anatomy_Gray

Anatomy_Gray. The perineum is divided into an anterior urogenital triangle and a posterior anal triangle. The urogenital triangle is associated with the openings of the urinary systems and the reproductive systems and functions to anchor the external genitalia. The anal triangle contains the anus and the external anal sphincter. The pudendal nerve (S2 to S4) and the internal pudendal artery are the major nerve and artery of the region. The margin of the perineum is marked by the inferior border of the pubic symphysis at its anterior point, the tip of the coccyx at its posterior point, and the ischial tuberosities at each of the lateral points (Fig. 5.69A). The lateral margins are formed by the ischiopubic rami anteriorly and by the sacrotuberous ligaments posteriorly. The pubic symphysis, the ischial tuberosities, and the coccyx can be palpated on the patient.


Anatomy_Gray

Anatomy_Gray. The perineum is divided into two triangles by an imaginary line between the two ischial tuberosities (Fig. 5.69A). Anterior to the line is the urogenital triangle and posterior to the line is the anal triangle. Significantly, the two triangles are not in the same plane. In the anatomical position, the urogenital triangle is oriented in the horizontal plane, whereas the anal triangle is tilted upward at the transtubercular line so that it faces more posteriorly. The roof of the perineum is formed mainly by the levator ani muscles that separate the pelvic cavity, above, from the perineum, below. These muscles, one on each side, form a coneor funnel-shaped pelvic diaphragm, with the anal aperture at its inferior apex in the anal triangle. Anteriorly, in the urogenital triangle, a U-shaped defect in the muscles, the urogenital hiatus, allows the passage of the urethra and vagina.


Anatomy_Gray

Anatomy_Gray. Anteriorly, in the urogenital triangle, a U-shaped defect in the muscles, the urogenital hiatus, allows the passage of the urethra and vagina. The perineal membrane (see pp. 449–451) is a thick fibrous sheet that fills the urogenital triangle (Fig. 5.69B). It has a free posterior border, which is anchored in the midline to the perineal body and is attached laterally to the pubic arch. Immediately superior to the perineal membrane is a thin region termed the deep perineal pouch, containing a layer of skeletal muscle and neurovascular tissues. Among the skeletal muscles in the pouch (see p. 451, Fig. 5.37) is the external urethral sphincter. The perineal membrane and deep perineal pouch provide support for the external genitalia, which are attached to its inferior surface. Also, the parts of the perineal membrane and deep perineal pouch inferior to the urogenital hiatus in the levator ani provide support for the pelvic viscera, above.


Anatomy_Gray

Anatomy_Gray. The urethra leaves the pelvic cavity and enters the perineum by passing through the deep perineal pouch and perineal membrane. In women, the vagina also passes through these structures posterior to the urethra.


Anatomy_Gray

Anatomy_Gray. Because the levator ani muscles course medially from their origin on the lateral pelvic walls, above, to the anal aperture and urogenital hiatus, below, inverted wedge-shaped gutters occur between the levator ani muscles and adjacent pelvic walls as the two structures diverge inferiorly (Fig. 5.70). In the anal triangle, these gutters, one on each side of the anal aperture, are termed ischio-anal fossae. The lateral wall of each fossa is formed mainly by the ischium, obturator internus muscle, and sacrotuberous ligament. The medial wall is the levator ani muscle. The medial and lateral walls converge superiorly where the levator ani muscle attaches to the fascia overlying the obturator internus muscle. The ischio-anal fossae allow movement of the pelvic diaphragm and expansion of the anal canal during defecation.


Anatomy_Gray

Anatomy_Gray. The ischio-anal fossae of the anal triangle are continuous anteriorly with recesses that project into the urogenital triangle superior to the deep perineal pouch. These anterior recesses of the ischio-anal fossae are shaped like three-sided pyramids that have been tipped onto one of their sides (Fig. 5.70C). The apex of each pyramid is closed and points anteriorly toward the pubis. The base is open and continuous posteriorly with its related ischio-anal fossa. The inferior wall of each pyramid is the deep perineal pouch. The superomedial wall is the levator ani muscle, and the superolateral wall is formed mainly by the obturator internus muscle. The ischio-anal fossae and their anterior recesses are normally filled with fat.


Anatomy_Gray

Anatomy_Gray. The anal triangle of the perineum faces posteroinferiorly and is defined laterally by the medial margins of the sacrotuberous ligaments, anteriorly by a horizontal line between the two ischial tuberosities, and posteriorly by the coccyx. The ceiling of the anal triangle is the pelvic diaphragm, which is formed by the levator ani and coccygeus muscles. The anal aperture occurs centrally in the anal triangle and is related on either side to an ischio-anal fossa. The major muscle in the anal triangle is the external anal sphincter.


Anatomy_Gray

Anatomy_Gray. The external anal sphincter, which surrounds the anal canal, is formed by skeletal muscle and consists of three parts—deep, superficial, and subcutaneous—arranged sequentially along the canal from superior to inferior (Fig. 5.69B, Table 5.5). The deep part is a thick ring-shaped muscle that circles the upper part of the anal canal and blends with the fibers of the levator ani muscle. The superficial part also surrounds the anal canal, but is anchored anteriorly to the perineal body and posteriorly to the coccyx and anococcygeal ligament. The subcutaneous part is a horizontally flattened disc of muscle that surrounds the anal aperture just beneath the skin. The external anal sphincter is innervated by inferior rectal branches of the pudendal nerve and by branches directly from the anterior ramus of S4.


Anatomy_Gray

Anatomy_Gray. The urogenital triangle of the perineum is the anterior half of the perineum and is oriented in the horizontal plane. It contains the roots of the external genitalia (Fig. 5.71) and the openings of the urogenital system. The urogenital triangle is defined: laterally by the ischiopubic rami, posteriorly by an imaginary line between the ischial tuberosities, and anteriorly by the inferior margin of the pubic symphysis. As with the anal triangle, the roof or ceiling of the urogenital triangle is the levator ani muscle. Unlike the anal triangle, the urogenital triangle contains a strong fibromuscular support platform, the perineal membrane and deep perineal pouch (see pp. 449–451), which is attached to the pubic arch. Anterior extensions of the ischio-anal fossae occur between the deep perineal pouch and the levator ani muscle on each side.


Anatomy_Gray

Anatomy_Gray. Anterior extensions of the ischio-anal fossae occur between the deep perineal pouch and the levator ani muscle on each side. Between the perineal membrane and the membranous layer of superficial fascia is the superficial perineal pouch. The principal structures in this pouch are the erectile tissues of the penis and clitoris and associated skeletal muscles. Structures in the superficial perineal pouch The superficial perineal pouch contains: erectile structures that join together to form the penis in men and the clitoris in women, and skeletal muscles that are associated mainly with parts of the erectile structures attached to the perineal membrane and adjacent bone. Each erectile structure consists of a central core of expandable vascular tissue and its surrounding connective tissue capsule. Two sets of erectile structures join to form the penis and the clitoris.


Anatomy_Gray

Anatomy_Gray. Two sets of erectile structures join to form the penis and the clitoris. A pair of cylindrically shaped corpora cavernosa, one on each side of the urogenital triangle, are anchored by their proximal ends to the pubic arch. These attached parts are often termed the crura (from the Latin for “legs”) of the clitoris or the penis. The distal ends of the corpora, which are not attached to bone, form the body of the clitoris in women and the dorsal parts of the body of the penis in men. The second set of erectile tissues surrounds the openings of the urogenital system.


Anatomy_Gray

Anatomy_Gray. The second set of erectile tissues surrounds the openings of the urogenital system. In women, a pair of erectile structures, termed the bulbs of the vestibule, are situated, one on each side, at the vaginal opening and are firmly anchored to the perineal membrane (Fig. 5.71A). Small bands of erectile tissues connect the anterior ends of these bulbs to a single, small, pea-shaped erectile mass, the glans clitoris, which is positioned in the midline at the end of the body of the clitoris and anterior to the opening of the urethra.


Anatomy_Gray

Anatomy_Gray. In men, a single large erectile mass, the corpus spongiosum, is the structural equivalent to the bulbs of the vestibule, the glans clitoris, and the interconnecting bands of erectile tissues in women (Fig. 5.71B). The corpus spongiosum is anchored at its base to the perineal membrane. Its proximal end, which is not attached, forms the ventral part of the body of the penis and expands over the end of the body of the penis to form the glans penis. This pattern in men results from the absence of a vaginal opening and from the fusion of structures across the midline during embryological development. As the originally paired erectile structures fuse, they enclose the urethral opening and form an additional channel that ultimately becomes most of the penile part of the urethra. As a consequence of this fusion and growth in men, the urethra is enclosed by the corpus spongiosum and opens at the end of the penis. This is unlike the situation in women, where the urethra is not enclosed by


Anatomy_Gray

Anatomy_Gray. of this fusion and growth in men, the urethra is enclosed by the corpus spongiosum and opens at the end of the penis. This is unlike the situation in women, where the urethra is not enclosed by erectile tissue of the clitoris and opens directly into the vestibule of the perineum.


Anatomy_Gray

Anatomy_Gray. The clitoris is composed of two corpora cavernosa and the glans clitoris (Fig. 5.71A). As in the penis, it has an attached part (root) and a free part (body). Unlike the root of the penis, the root of the clitoris technically consists only of the two crura. (Although the bulbs of the vestibule are attached to the glans clitoris by thin bands of erectile tissue, they are not included in the attached part of the clitoris.) The body of the clitoris, which is formed only by the unattached parts of the two corpora cavernosa, angles posteriorly and is embedded in the connective tissues of the perineum. The body of the clitoris is supported by a suspensory ligament that attaches superiorly to the pubic symphysis. The glans clitoris is attached to the distal end of the body and is connected to the bulbs of the vestibule by small bands of erectile tissue. The glans clitoris is exposed in the perineum and the body of the clitoris can be palpated through skin.


Anatomy_Gray

Anatomy_Gray. The penis is composed mainly of the two corpora cavernosa and the single corpus spongiosum, which contains the urethra (Fig. 5.71B.) As in the clitoris, it has an attached part (root) and a free part (body): The root of the penis consists of the two crura, which are proximal parts of the corpora cavernosa attached to the pubic arch, and the bulb of the penis, which is the proximal part of the corpus spongiosum anchored to the perineal membrane. The body of the penis, which is covered entirely by skin, is formed by the tethering of the two proximal free parts of the corpora cavernosa and the related free part of the corpus spongiosum.


Anatomy_Gray

Anatomy_Gray. The body of the penis, which is covered entirely by skin, is formed by the tethering of the two proximal free parts of the corpora cavernosa and the related free part of the corpus spongiosum. The base of the body of the penis is supported by two ligaments: the suspensory ligament of the penis (attached superiorly to the pubic symphysis), and the more superficially positioned fundiform ligament of the penis (attached above to the linea alba of the anterior abdominal wall and split below into two bands that pass on each side of the penis and unite inferiorly). Because the anatomical position of the penis is erect, the paired corpora are defined as dorsal in the body of the penis and the single corpus spongiosum as ventral, even though the positions are reversed in the nonerect (flaccid) penis. The corpus spongiosum expands to form the head of the penis (glans penis) over the distal ends of the corpora cavernosa (Fig. 5.71B).


Anatomy_Gray

Anatomy_Gray. The corpus spongiosum expands to form the head of the penis (glans penis) over the distal ends of the corpora cavernosa (Fig. 5.71B). Erection of the penis and clitoris is a vascular event generated by parasympathetic fibers carried in pelvic splanchnic nerves from the anterior rami of S2 to S4, which enter the inferior hypogastric part of the prevertebral plexus and ultimately pass through the deep perineal pouch and perineal membrane to innervate the erectile tissues. Stimulation of these nerves causes specific arteries in the erectile tissues to relax. This allows blood to fill the tissues, causing the penis and clitoris to become erect. Arteries supplying the penis and clitoris are branches of the internal pudendal artery; branches of the pudendal nerve (S2 to S4) carry general sensory nerves from the penis and clitoris.


Anatomy_Gray

Anatomy_Gray. Arteries supplying the penis and clitoris are branches of the internal pudendal artery; branches of the pudendal nerve (S2 to S4) carry general sensory nerves from the penis and clitoris. The greater vestibular glands (Bartholin’s glands) are seen in women. They are small, pea-shaped mucous glands that lie posterior to the bulbs of the vestibule on each side of the vaginal opening and are the female homologues of the bulbo-urethral glands in men (Fig. 5.71). However, the bulbo-urethral glands are located within the deep perineal pouch, whereas the greater vestibular glands are in the superficial perineal pouch. The duct of each greater vestibular gland opens into the vestibule of the perineum along the posterolateral margin of the vaginal opening. Like the bulbo-urethral glands in men, the greater vestibular glands produce secretion during sexual arousal.


Anatomy_Gray

Anatomy_Gray. Like the bulbo-urethral glands in men, the greater vestibular glands produce secretion during sexual arousal. The superficial perineal pouch contains three pairs of muscles: the ischiocavernosus, bulbospongiosus, and superficial transverse perineal muscles (Fig. 5.72 and Table 5.6). Two of these three pairs of muscles are associated with the roots of the penis and clitoris; the other pair is associated with the perineal body. The two ischiocavernosus muscles cover the crura of the penis and clitoris (Fig. 5.72). Each muscle is anchored to the medial margin of the ischial tuberosity and related ischial ramus and passes forward to attach to the sides and inferior surface of the related crus, and forces blood from the crus into the body of the erect penis and clitoris. The two bulbospongiosus muscles are associated mainly with the bulbs of the vestibule in women and with the attached part of the corpus spongiosum in men (Fig. 5.72).


Anatomy_Gray

Anatomy_Gray. The two bulbospongiosus muscles are associated mainly with the bulbs of the vestibule in women and with the attached part of the corpus spongiosum in men (Fig. 5.72). In women, each bulbospongiosus muscle is anchored posteriorly to the perineal body and courses anterolaterally over the inferior surface of the related greater vestibular gland and the bulb of the vestibule to attach to the surface of the bulb and to the perineal membrane (Fig. 5.72A). Other fibers course anterolaterally to blend with the fibers of the ischiocavernosus muscle, and still others travel anteriorly and arch over the body of the clitoris.


Anatomy_Gray

Anatomy_Gray. In men, the bulbospongiosus muscles are joined in the midline to a raphe on the inferior surface of the bulb of the penis. The raphe is anchored posteriorly to the perineal body. Muscle fibers course anterolaterally, on each side, from the raphe and perineal body to cover each side of the bulb of the penis and attach to the perineal membrane and connective tissue of the bulb. Others extend anterolaterally to associate with the crura and attach anteriorly to the ischiocavernosus muscles. In both men and women, the bulbospongiosus muscles compress attached parts of the erect corpus spongiosum and bulbs of the vestibule and force blood into more distal regions, mainly the glans. In men, the bulbospongiosus muscles have two additional functions: They facilitate emptying of the bulbous part of the penile urethra following urination (micturition). Their reflex contraction during ejaculation is responsible for the pulsatile emission of semen from the penis.


Anatomy_Gray

Anatomy_Gray. Their reflex contraction during ejaculation is responsible for the pulsatile emission of semen from the penis. The paired superficial transverse perineal muscles follow a course parallel to the posterior margin of the inferior surface of the perineal membrane (Fig. 5.72). These flat band-shaped muscles, which are attached to ischial tuberosities and rami, extend medially to the perineal body in the midline and stabilize the perineal body. Superficial features of the external genitalia


Anatomy_Gray

Anatomy_Gray. Superficial features of the external genitalia In women, the clitoris and vestibular apparatus, together with a number of skin and tissue folds, form the vulva (Fig. 5.73). On either side of the midline are two thin folds of skin termed the labia minora. The region enclosed between them, and into which the urethra and vagina open, is the vestibule. Anteriorly, the labia minora each bifurcate, forming a medial and a lateral fold. The medial folds unite to form the frenulum of the clitoris, that joins the glans clitoris. The lateral folds unite ventrally over the glans clitoris and the body of the clitoris to form the prepuce of the clitoris (hood). The body of the clitoris extends anteriorly from the glans clitoris and is palpable deep to the prepuce and related skin. Posterior to the vestibule, the labia minora unite, forming a small transverse fold, the frenulum of the labia minora (the fourchette).


Anatomy_Gray

Anatomy_Gray. Within the vestibule, the vaginal orifice is surrounded to varying degrees by a ring-like fold of membrane, the hymen, which may have a small central perforation or may completely close the vaginal opening. Following rupture of the hymen (resulting from first sexual intercourse or injury), irregular remnants of the hymen fringe the vaginal opening. The orifices of the urethra and the vagina are associated with the openings of glands. The ducts of the para-urethral glands (Skene’s glands) open into the vestibule, one on each side of the lateral margin of the urethra. The ducts of the greater vestibular glands (Bartholin’s glands) open adjacent to the posterolateral margin of the vaginal opening in the crease between the vaginal orifice and remnants of the hymen.


Anatomy_Gray

Anatomy_Gray. Lateral to the labia minora are two broad folds, the labia majora, which unite anteriorly to form the mons pubis. The mons pubis overlies the inferior aspect of the pubic symphysis and is anterior to the vestibule and the clitoris. Posteriorly, the labia majora do not unite and are separated by a depression termed the posterior commissure, which overlies the position of the perineal body.


Anatomy_Gray

Anatomy_Gray. Superficial components of the genital organs in men consist of the scrotum and the penis (Fig. 5.74). The scrotum is the male homologue of the labia majora in women. In the fetus, labioscrotal swellings fuse across the midline, resulting in a single scrotum into which the testes and their associated musculofascial coverings, blood vessels, nerves, lymphatics, and drainage ducts descend from the abdomen. The remnant of the line of fusion between the labioscrotal swellings in the fetus is visible on the skin of the scrotum as a longitudinal midline raphe that extends from the anus, over the scrotal sac, and onto the inferior aspect of the body of the penis. The penis consists of a root and body. The attached root of the penis is palpable posterior to the scrotum in the urogenital triangle of the perineum. The pendulous part of the penis (body of penis) is entirely covered by skin; the tip of the body is covered by the glans penis.


Anatomy_Gray

Anatomy_Gray. The external urethral orifice is a sagittal slit, normally positioned at the tip of the glans. The inferior margin of the urethral orifice is continuous with a midline raphe of the penis, which represents a line of fusion formed in the glans as the urethra develops in the fetus. The base of this raphe is continuous with the frenulum of the glans, which is a median fold of skin that attaches the glans to more loosely attached skin proximal to the glans. The base of the glans is expanded to form a raised circular margin (the corona of the glans); the two lateral ends of the corona join inferiorly at the midline raphe of the glans. The depression posterior to the corona is the neck of the glans. Normally, a fold of skin at the neck of the glans is continuous anteriorly with thin skin that tightly adheres to the glans and posteriorly with thicker skin loosely attached to the body. This fold, known as the prepuce, extends forward to cover the glans. The prepuce is removed during male


Anatomy_Gray

Anatomy_Gray. tightly adheres to the glans and posteriorly with thicker skin loosely attached to the body. This fold, known as the prepuce, extends forward to cover the glans. The prepuce is removed during male circumcision, leaving the glans exposed.


Anatomy_Gray

Anatomy_Gray. Superficial fascia of the urogenital triangle The superficial fascia of the urogenital triangle is continuous with similar fascia on the anterior abdominal wall. As with the superficial fascia of the abdominal wall, the perineal fascia has a membranous layer on its deep surface. This membranous layer (Colles’ fascia), is attached: posteriorly to the perineal membrane and therefore does not extend into the anal triangle (Fig. 5.75), and to the ischiopubic rami that form the lateral borders of the urogenital triangle and therefore does not extend into the thigh (Fig. 5.75). It defines the external limits of the superficial perineal pouch, lines the scrotum or labia, and extends around the body of the penis and clitoris.


Anatomy_Gray

Anatomy_Gray. It defines the external limits of the superficial perineal pouch, lines the scrotum or labia, and extends around the body of the penis and clitoris. Anteriorly, the membranous layer of fascia is continuous over the pubic symphysis and pubic bones with the membranous layer of fascia on the anterior abdominal wall. In the lower lateral abdominal wall, the membranous layer of abdominal fascia is attached to the deep fascia of the thigh just inferior to the inguinal ligament. Because the membranous layer of fascia encloses the superficial perineal pouch and continues up the anterior abdominal wall, fluids or infectious materials that accumulate in the pouch can track out of the perineum and onto the lower abdominal wall. This material will not track into the anal triangle or the thigh because the fascia fuses with deep tissues at the borders of these regions.


Anatomy_Gray

Anatomy_Gray. The major somatic nerve of the perineum is the pudendal nerve. This nerve originates from the sacral plexus and carries fibers from spinal cord levels S2 to S4. It leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle, passes around the sacrospinous ligament, and then enters the anal triangle of the perineum by passing medially through the lesser sciatic foramen. As it enters and courses through the perineum, it travels along the lateral wall of the ischio-anal fossa in the pudendal canal, which is a tubular compartment formed in the fascia that covers the obturator internus muscle. This pudendal canal also contains the internal pudendal artery and accompanying veins. The pudendal nerve (Fig. 5.76) has three major terminal branches—the inferior rectal and perineal nerves and the dorsal nerve of the penis or clitoris—which are accompanied by branches of the internal pudendal artery (Fig. 5.77).


Anatomy_Gray

Anatomy_Gray. The inferior rectal nerve is often multiple, penetrates through the fascia of the pudendal canal, and courses medially across the ischio-anal fossa to innervate the external anal sphincter and related regions of the levator ani muscles. The nerve is also general sensory for the skin of the anal triangle. The perineal nerve passes into the urogenital triangle and gives rise to motor and cutaneous branches. The motor branches supply skeletal muscles in the superficial and deep perineal pouches. The largest of the sensory branches is the posterior scrotal nerve in men and the posterior labial nerve in women.


Anatomy_Gray

Anatomy_Gray. The dorsal nerve of the penis and clitoris enters the deep perineal pouch (Fig. 5.76). It passes along the lateral margin of the pouch and then exits by passing inferiorly through the perineal membrane in a position just inferior to the pubic symphysis where it meets the body of the clitoris or the penis. It courses along the dorsal surface of the body to reach the glans. The dorsal nerve is sensory to the penis and clitoris, particularly to the glans. Other somatic nerves that enter the perineum are mainly sensory and include branches of the ilio-inguinal, genitofemoral, posterior femoral cutaneous, and anococcygeal nerves. Visceral nerves enter the perineum by two routes:


Anatomy_Gray

Anatomy_Gray. Visceral nerves enter the perineum by two routes: Those to the skin, which consist mainly of postganglionic sympathetics, are delivered into the region along the pudendal nerve. These fibers join the pudendal nerve from gray rami communicantes that connect pelvic parts of the sympathetic trunks to the anterior rami of the sacral spinal nerves (see p. 481 and Fig. 5.62). Those to erectile tissues enter the region mainly by passing through the deep perineal pouch from the inferior hypogastric plexus in the pelvic cavity (see p. 488 and Fig. 5.63B). The fibers that stimulate erection are parasympathetic fibers, which enter the inferior hypogastric plexus via pelvic splanchnic nerves from spinal cord levels of S2 to S4 (see Fig. 5.63A,B). The most significant artery of the perineum is the internal pudendal artery (Fig. 5.77). Other arteries entering the area include the external pudendal, the testicular, and the cremasteric arteries.


Anatomy_Gray

Anatomy_Gray. The most significant artery of the perineum is the internal pudendal artery (Fig. 5.77). Other arteries entering the area include the external pudendal, the testicular, and the cremasteric arteries. The internal pudendal artery originates as a branch of the anterior trunk of the internal iliac artery in the pelvis (Fig. 5.77). Along with the pudendal nerve, it leaves the pelvis through the greater sciatic foramen inferior to the piriformis muscle. It passes around the ischial spine, where the artery lies lateral to the nerve, enters the perineum by coursing through the lesser sciatic foramen, and accompanies the pudendal nerve in the pudendal canal on the lateral wall of the ischio-anal fossa. The branches of the internal pudendal artery are similar to those of the pudendal nerve in the perineum and include the inferior rectal and perineal arteries, and branches to the erectile tissues of the penis and clitoris (Fig. 5.77).


Anatomy_Gray

Anatomy_Gray. One or more inferior rectal arteries originate from the internal pudendal artery in the anal triangle and cross the ischio-anal fossa medially to branch and supply muscle and related skin (Fig. 5.77). They anastomose with middle and superior rectal arteries from the internal iliac artery and the inferior mesenteric artery, respectively, to form a network of vessels that supply the rectum and anal canal. The perineal artery originates near the anterior end of the pudendal canal and gives off a transverse perineal branch, and a posterior scrotal or labial artery to surrounding tissues and skin (Fig. 5.77). Terminal part of the internal pudendal artery The terminal part of the internal pudendal artery accompanies the dorsal nerve of the penis or clitoris into the deep perineal pouch and supplies branches to the tissues in the deep perineal pouch and erectile tissues.


Anatomy_Gray

Anatomy_Gray. Branches that supply the erectile tissues in men include the artery to the bulb of the penis, the urethral artery, the deep artery of the penis, and the dorsal artery of the penis (Fig. 5.77). The artery of the bulb of the penis has a branch that supplies the bulbo-urethral gland and then penetrates the perineal membrane to supply the corpus spongiosum. A urethral artery also penetrates the perineal membrane and supplies the penile urethra and surrounding erectile tissue to the glans.


Anatomy_Gray

Anatomy_Gray. A urethral artery also penetrates the perineal membrane and supplies the penile urethra and surrounding erectile tissue to the glans. Near the anterior margin of the deep perineal pouch, the internal pudendal artery bifurcates into two terminal branches. A deep artery of the penis penetrates the perineal membrane to enter the crus and supply the crus and corpus cavernosum of the body. The dorsal artery of the penis penetrates the anterior margin of the perineal membrane to meet the dorsal surface of the body of the penis. The vessel courses along the dorsal surface of the penis, medial to the dorsal nerve, and supplies the glans penis and superficial tissues of the penis; it also anastomoses with branches of the deep artery of the penis and the urethral artery. Branches that supply the erectile tissues in women are similar to those in men. Arteries of the bulb of the vestibule supply the bulb of the vestibule and related vagina.


Anatomy_Gray

Anatomy_Gray. Branches that supply the erectile tissues in women are similar to those in men. Arteries of the bulb of the vestibule supply the bulb of the vestibule and related vagina. Deep arteries of the clitoris supply the crura and corpus cavernosum of the body. Dorsal arteries of the clitoris supply surrounding tissues and the glans. The external pudendal arteries consist of a superficial vessel and a deep vessel, which originate from the femoral artery in the thigh. They course medially to enter the perineum anteriorly and supply related skin of the penis and scrotum or the clitoris and labia majora. In men, the testicular arteries originate from the abdominal aorta and descend into the scrotum through the inguinal canal to supply the testes. Also, cremasteric arteries, which originate from the inferior epigastric branch of the external iliac artery, accompany the spermatic cord into the scrotum.


Anatomy_Gray

Anatomy_Gray. In women, small cremasteric arteries follow the round ligament of the uterus through the inguinal canal. Veins in the perineum generally accompany the arteries and join the internal pudendal veins that connect with the internal iliac vein in the pelvis (Fig. 5.78). The exception is the deep dorsal vein of the penis or clitoris that drains mainly the glans and the corpora cavernosa. The deep dorsal vein courses along the midline between the dorsal arteries on each side of the body of the penis or clitoris, passes though the gap between the inferior pubic ligament and the deep perineal pouch, and connects with the plexus of veins surrounding the prostate in men or bladder in women.


Anatomy_Gray

Anatomy_Gray. External pudendal veins, which drain anterior parts of the labia majora or the scrotum and overlap with the area of drainage of the internal pudendal veins, connect with the femoral vein in the thigh. Superficial dorsal veins of the penis or clitoris that drain skin are tributaries of the external pudendal veins. Lymphatic vessels from deep parts of the perineum accompany the internal pudendal blood vessels and drain mainly into internal iliac nodes in the pelvis. Lymphatic channels from superficial tissues of the penis or the clitoris accompany the superficial external pudendal blood vessels and drain mainly into superficial inguinal nodes, as do lymphatic channels from the scrotum or labia majora (Fig. 5.79). The glans penis, glans clitoris, labia minora, and terminal inferior end of the vagina drain into deep inguinal nodes and external iliac nodes.


Anatomy_Gray

Anatomy_Gray. Lymphatics from the testes drain via channels that ascend in the spermatic cord, pass through the inguinal canal, and course up the posterior abdominal wall to connect directly with lateral aortic or lumbar nodes and pre-aortic nodes around the aorta, at approximately vertebral levels LI and LII. Therefore disease from the testes tracks superiorly to nodes high in the posterior abdominal wall and not to inguinal or iliac nodes. Surface anatomy of the pelvis and perineum Palpable bony features of the pelvis are used as landmarks for: locating soft tissue structures, visualizing the orientation of the pelvic inlet, and defining the margins of the perineum. The ability to recognize the normal appearance of structures in the perineum is an essential part of a physical examination. In women, the cervix can be visualized directly by opening the vaginal canal using a speculum.


Anatomy_Gray

Anatomy_Gray. In women, the cervix can be visualized directly by opening the vaginal canal using a speculum. In men, the size and texture of the prostate in the pelvic cavity can be assessed by digital palpation through the anal aperture. Orientation of the pelvis and perineum in the anatomical position In the anatomical position, the anterior superior iliac spines and the anterior superior edge of the pubic symphysis lie in the same vertical plane. The pelvic inlet faces anterosuperiorly. The urogenital triangle of the perineum is oriented in an almost horizontal plane and faces inferiorly, whereas the anal triangle is more vertical and faces posteriorly (Figs. 5.80 and 5.81). How to define the margins of the perineum The pubic symphysis, ischial tuberosities, and tip of the sacrum are palpable on patients and can be used to define the boundaries of the perineum. This is best done with patients lying on their backs with their thighs flexed and abducted in the lithotomy position (Fig. 5.82).


Anatomy_Gray

Anatomy_Gray. The ischial tuberosities are palpable on each side as large bony masses near the crease of skin (gluteal fold) between the thigh and gluteal region. They mark the lateral corners of the diamond-shaped perineum. The tip of the coccyx is palpable in the midline posterior to the anal aperture and marks the most posterior limit of the perineum. The anterior limit of the perineum is the pubic symphysis. In women, this is palpable in the midline deep to the mons pubis. In men, the pubic symphysis is palpable immediately superior to where the body of the penis joins the lower abdominal wall.


Anatomy_Gray

Anatomy_Gray. Imaginary lines that join the ischial tuberosities with the pubic symphysis in front, and with the tip of the coccyx behind, outline the diamond-shaped perineum. An additional line between the ischial tuberosities divides the perineum into two triangles, the urogenital triangle anteriorly and anal triangle posteriorly. This line also approximates the position of the posterior margin of the perineal membrane. The midpoint of this line marks the location of the perineal body or central tendon of the perineum. Identification of structures in the anal triangle


Anatomy_Gray

Anatomy_Gray. Identification of structures in the anal triangle The anal triangle is the posterior half of the perineum. The base of the triangle faces anteriorly and is an imaginary line joining the two ischial tuberosities. The apex of the triangle is the tip of the coccyx; the lateral margins can be approximated by lines joining the coccyx to the ischial tuberosities. In both women and men, the major feature of the anal triangle is the anal aperture in the center of the triangle. Fat fills the ischio-anal fossa on each side of the anal aperture (Fig. 5.83). Identification of structures in the urogenital triangle of women


Anatomy_Gray

Anatomy_Gray. Identification of structures in the urogenital triangle of women The urogenital triangle is the anterior half of the perineum. The base of the triangle faces posteriorly and is an imaginary line joining the two ischial tuberosities. The apex of the triangle is the pubic symphysis. The lateral margins can be approximated by lines joining the pubic symphysis to the ischial tuberosities. These lines overlie the ischiopubic rami, which can be felt on deep palpation. In women, the major contents of the urogenital triangle are the clitoris, the vestibule, and skin folds that together form the vulva (Fig. 5.84A,B).


Anatomy_Gray

Anatomy_Gray. In women, the major contents of the urogenital triangle are the clitoris, the vestibule, and skin folds that together form the vulva (Fig. 5.84A,B). Two thin skin folds, the labia minora, enclose between them a space termed the vestibule into which the vagina and the urethra open (Fig. 5.84C). Gentle lateral traction on the labia minora opens the vestibule and reveals a soft tissue mound on which the urethra opens. The para-urethral (Skene’s) glands, one on each side, open into the skin crease between the urethra and the labia minora (Fig. 5.84D). Posterior to the urethra is the vaginal opening. The vaginal opening (introitus) is ringed by remnants of the hymen that originally closes the vaginal orifice and is usually ruptured during the first sexual intercourse. The ducts of the greater vestibular (Bartholin’s) glands, one on each side, open into the skin crease between the hymen and the adjacent labium minus (Fig. 5.84D).


Anatomy_Gray

Anatomy_Gray. The labia minora each bifurcate anteriorly into medial and lateral folds. The medial folds unite at the midline to form the frenulum of the clitoris. The larger lateral folds also unite across the midline to form the clitoral hood or prepuce that covers the glans clitoris and distal parts of the body of the clitoris. Posterior to the vaginal orifice, the labia minora join, forming a transverse skin fold (the fourchette). The labia majora are broad folds positioned lateral to the labia minora. They come together in front to form the mons pubis, which overlies the inferior aspect of the pubic symphysis. The posterior ends of the labia majora are separated by a depression termed the posterior commissure, which overlies the position of the perineal body.


Anatomy_Gray

Anatomy_Gray. The cervix is visible when the vaginal canal is opened with a speculum (Fig. 5.84E). The external cervical os opens onto the surface of the dome-shaped cervix. A recess or gutter, termed the fornix, occurs between the cervix and the vaginal wall and is further subdivided, based on location, into anterior, posterior, and lateral fornices. The roots of the clitoris occur deep to surface features of the perineum and are attached to the ischiopubic rami and the perineal membrane. The bulbs of the vestibule (Fig. 5.84F), composed of erectile tissues, lie deep to the labia minora on either side of the vestibule. These erectile masses are continuous, via thin bands of erectile tissues, with the glans clitoris, which is visible under the clitoral hood. The greater vestibular glands occur posterior to the bulbs of the vestibule on either side of the vaginal orifice.


Anatomy_Gray

Anatomy_Gray. The crura of the clitoris are attached, one on each side, to the ischiopubic rami. Each crus is formed by the attached part of the corpus cavernosum. Anteriorly, these erectile corpora detach from bone, curve posteroinferiorly, and unite to form the body of the clitoris. The body of the clitoris underlies the ridge of skin immediately anterior to the clitoral hood (prepuce). The glans clitoris is positioned at the end of the body of the clitoris. Identification of structures in the urogenital triangle of men In men, the urogenital triangle contains the root of the penis. The testes and associated structures, although they migrate into the scrotum from the abdomen, are generally evaluated with the penis during a physical examination.


Anatomy_Gray

Anatomy_Gray. The scrotum in men is homologous to the labia majora in women. Each oval testis is readily palpable through the skin of the scrotum (Fig. 5.85A). Posterolateral to the testis is an elongated mass of tissue, often visible as a raised ridge that contains lymphatics and blood vessels of the testis, and the epididymis and ductus deferens. A midline raphe (Fig. 5.85B) is visible on the skin separating left and right sides of the scrotum. In some individuals, this raphe is prominent and extends from the anal aperture, over the scrotum and along the ventral surface of the body of the penis, to the frenulum of the glans. The root of the penis is formed by the attached parts of the corpus spongiosum and the corpora cavernosa. The corpus spongiosum is attached to the perineal membrane and can be easily palpated as a large mass anterior to the perineal body. This mass, which is covered by the bulbospongiosus muscles, is the bulb of penis.


Anatomy_Gray

Anatomy_Gray. The corpus spongiosum detaches from the perineal membrane anteriorly, becomes the ventral part of the body of the penis (shaft of penis), and eventually terminates as the expanded glans penis (Fig. 5.85C,D). The crura of the penis, one crus on each side, are the attached parts of the corpora cavernosa and are anchored to the ischiopubic rami (Fig. 5.85E). The corpora cavernosa are unattached anteriorly and become the paired erectile masses that form the dorsal part of the body of the penis. The glans penis caps the anterior ends of the corpora cavernosa. Fig. 5.1 Pelvis and perineum. Fig. 5.2 The pelvis and perineum contain and support terminal parts of the gastrointestinal, urinary, and reproductive systems. A. In women. B. In men. Fig. 5.3 The perineum contains and anchors the roots of the external genitalia. A. In women. B. In men.


Anatomy_Gray

Anatomy_Gray. Fig. 5.3 The perineum contains and anchors the roots of the external genitalia. A. In women. B. In men. Obturator foramenIschialtuberosityPerineal membraneRoots of external genitaliaBody of clitorisUrethral orificeVaginal orificeGlans of clitorisObturator foramenIschial tuberosityRoot of penisBody of penisOpening of urethraGlans of penisPerineal membraneAB Fig. 5.4 Pelvic inlet. Pelvic inletAla of sacrumSacro-iliac jointCoccyxIschial spineAnterior superior iliac spineObturator foramenIschial tuberosityPubic symphysisIschiopubic ramusPubic tubercleSI body Fig. 5.5 Pelvic walls. A. Bones and ligaments of the pelvic walls. B. Muscles of the pelvic walls. Greater sciatic foramenLesser sciatic foramenObturator foramenSacrotuberous ligamentSacrospinous ligamentIschial tuberosityIschiopubic ramusPubic tubercleAnterior superioriliac spineMargin of pelvic inletA Margin of pelvic inletPiriformis muscleObturator internus muscleB Fig. 5.6 Pelvic outlet.


Anatomy_Gray

Anatomy_Gray. Margin of pelvic inletPiriformis muscleObturator internus muscleB Fig. 5.6 Pelvic outlet. Ischiopubic ramusPubic symphysisIschial tuberosityCoccyxSacrotuberous ligamentPubic tubercleObturator foramenAnterior superior iliac spineAcetabulumMargin of pelvic outletSacrum Fig. 5.7 Pelvic floor. Fig. 5.8 Pelvic cavity and peritoneum. A. In men (sagittal section). B. In women (anterior view). Pelvic cavity linedby peritoneumAPerineal membraneand deep perineal pouchLevator aniRectumAortaPeritoneumPelvic inletExternal iliac arteryInternal iliac artery(artery of pelvis)BladderUterusB Fig. 5.9 Perineum. A. In women. B. In men. Roots of external genitaliaPerineal membraneLevator aniSacrotuberous ligamentAnal triangleAnal apertureUrethral orificeUrogenital triangleVaginal orificeRoots of external genitaliaLevator aniAnal apertureAnal triangleUrogenital trianglePerineal membraneABUrethral orifice


Anatomy_Gray

Anatomy_Gray. Fig. 5.10 Areas of communication between the true pelvis and other regions. A. Between the true pelvis, abdomen, and lower limb. B. Between the perineum and other regions. Gap between pubic symphysis and perineal membrane• Dorsal vein of penis and clitorisSacrotuberous ligamentSacrospinous ligamentOrifices in floor• Urethra• Vagina• AnusLesser sciatic foramen• Obturator internus muscle• Pudendal nerve• Internal pudendal vein and arteryB Fig. 5.11 Orientation of the pelvis and pelvic cavity in the anatomical position. Coronal planeAnterior superioriliac spinePubic tuberclePubic symphysisSacrumSacrospinous ligamentSacrotuberous ligamentAnal triangle of perineumUrogenital triangle of perineumPelvic inlet Fig. 5.12 Structures that cross the ureters in the pelvic cavity. A. In women. B. In men. Fig. 5.13 Position of the prostate gland. Fig. 5.14 Dermatomes of the perineum. A. In women. B. In men. Fig. 5.15 Pudendal nerve.


Anatomy_Gray

Anatomy_Gray. Fig. 5.13 Position of the prostate gland. Fig. 5.14 Dermatomes of the perineum. A. In women. B. In men. Fig. 5.15 Pudendal nerve. S1S2S3S4Sacrospinous ligamentPudendal nerveIschial spineAttachment of levatorani and coccygeus(pelvic floor) Fig. 5.16 Pelvic splanchnic nerves from spinal levels S2 to S4 control erection. Hypogastric nerveInferior hypogastric plexusAttachment of pelvic floor(levator ani and coccygeus)Pelvic splanchnic nerves(from S2 to S4)Urogenital triangleAnal triangleProstateNerves to erectile tissue Fig. 5.17 Perineal body. Fig. 5.18 Course of the urethra. A. In women. B. In men. Fig. 5.19 Right pelvic bone. A. Medial view. B. Lateral view. Fig. 5.20 Ilium, ischium, and pubis. Fig. 5.21 Components of the pelvic bone. A. Medial surface. B. Lateral surface. Fig. 5.22 Sacrum and coccyx. A. Anterior view. B. Posterior view. C. Lateral view. Fig. 5.23 Lumbosacral joints and associated ligaments. A. Lateral view. B. Anterior view.


Anatomy_Gray

Anatomy_Gray. Fig. 5.22 Sacrum and coccyx. A. Anterior view. B. Posterior view. C. Lateral view. Fig. 5.23 Lumbosacral joints and associated ligaments. A. Lateral view. B. Anterior view. Fig. 5.24 Sacro-iliac joints and associated ligaments. A. Lateral view. B. Anterior view. C. Posterior view. Fig. 5.25 Pubic symphysis and associated ligaments. Fig. 5.26 Orientation of the pelvis (anatomical position). Fig. 5.27 Structure of the bony pelvis. A. In women. B. In men. The angle formed by the pubic arch can be approximated by the angle between the thumb and index finger for women and the angle between the index finger and middle finger for men as shown in the insets. Fig. 5.28 Pelvic inlet. PromontoryMargin of alaSacro-iliac jointArcuatelinePectenpubisPubic crestLinea terminalisPubic symphysisPubictubercle Fig. 5.29 Sacrospinous and sacrotuberous ligaments. A. Medial view of right side of pelvis. B. Function of the ligaments.


Anatomy_Gray

Anatomy_Gray. Fig. 5.29 Sacrospinous and sacrotuberous ligaments. A. Medial view of right side of pelvis. B. Function of the ligaments. Fig. 5.30 Obturator internus and piriformis muscles (medial view of right side of pelvis). Fig. 5.31 Apertures in the pelvic wall. Obturator canal – obturator nerve and vesselsObturator internus muscleGreater sciatic foramen,above and belowpiriformis muscleLesser sciatic foramenSuperior gluteal nerveand vesselsSciatic nerve, inferior gluteal, posterior femoral cutaneous,and quadratus femoris nerves,and the inferior gluteal and internal pudendal vesselsPudendal nerve and internalpudendal vessels and nerveto obturator internus Fig. 5.32 Pelvic outlet. Pubic archPubic symphysisIschial tuberosityBody of pubisCoccyxSacrotuberous ligament Fig. 5.33 Sagittal T2-weighted magnetic resonance image of the lower abdomen and pelvis of a pregnant woman. Fig. 5.34 Pelvic diaphragm. Fig. 5.35 MRI defecating proctogram in sagittal plane showing active defecation.


Anatomy_Gray

Anatomy_Gray. Fig. 5.34 Pelvic diaphragm. Fig. 5.35 MRI defecating proctogram in sagittal plane showing active defecation. Fig. 5.36 Perineal membrane and deep perineal pouch. A. Inferior view. B. Superolateral view. Perineal membrane and deep perineal pouch. C. Medial view. Obturator foramenIschiopubic ramusIschial tuberosityPubic symphysisOpening for urethraLine of attachment for margin ofurogenital hiatus of levator aniDeep perineal pouchBAInferior pubic ligamentPerineal membranePerineal membrane Obturator internus muscleCoccygeus muscleAnococcygeal ligamentLevator ani muscleSacrospinous ligamentRoot of penisCDeep perineal pouchPerineal membrane Fig. 5.37 Muscles in the deep perineal pouch. A. In women. B. In men. Fig. 5.38 Perineal body. Fig. 5.39 Rectum and anal canal. A. Left pelvic bone removed. B. Longitudinal section. Fig. 5.40 Pelvic parts of the urinary system.


Anatomy_Gray

Anatomy_Gray. B. In men. Fig. 5.38 Perineal body. Fig. 5.39 Rectum and anal canal. A. Left pelvic bone removed. B. Longitudinal section. Fig. 5.40 Pelvic parts of the urinary system. External iliac arteryInternal iliac arteryCommon iliac arteryUreterUrethraNeck of bladderBladderFull bladderEmpty bladder Fig. 5.41 Bladder. A. Superolateral view. B. The trigone. Anterior view with the anterior part of the bladder cut away. Internal urethralorificeOpening of uretersUretersUretersUrethraUrethraInferolateralsurfacesSuperior surfaceApexTrigoneTrigoneMedianumbilicalligamentABBase Fig. 5.42 Ligaments that anchor the neck of the bladder and pelvic part of the urethra to the pelvic bones. A. In women. B. In men. Fig. 5.43 Intravenous urogram demonstrating a stone in the lower portion of the ureter. A. Control radiograph. B. Intravenous urogram, postmicturition. Fig. 5.44 Intravenous urogram demonstrating a small tumor in the wall of the bladder. Fig. 5.45 Urethra. A. In women. B. In men.


Anatomy_Gray

Anatomy_Gray. Fig. 5.44 Intravenous urogram demonstrating a small tumor in the wall of the bladder. Fig. 5.45 Urethra. A. In women. B. In men. C. Prostatic part of the urethra in men. 4. Spongy part of urethraBladderBladderProstate2nd bend when penis is flaccidABBulbo-urethral gland and duct1st bendPenisInternal urethral sphincter(smooth muscle)External urethral sphincter(skeletal muscle)Deep perineal pouchPerineal membraneGlans clitorisExternal urethral sphincterNavicular fossaDeep perineal pouchPerineal membraneExternal urethral orificeDuct of Skene's glandPara-urethral gland (Skene's gland)Greater vestibular gland Vaginal opening in deep perineal pouchand perineal membraneExternal urethral orifice3. Membranous part of urethra2. Prostatic part of urethraUrethra1. Preprostatic part of urethra


Anatomy_Gray

Anatomy_Gray. Prostatic utricleExternal urethralsphincter (skeletal muscle)COpenings ofejaculatory ductsOpenings ofducts of glandularelements of prostateProstateInternal urethral sphincter(smooth muscle)Urethral crestSeminal colliculusGlandular elementsof prostateFibromuscularstroma(smooth muscle andfibrous connective tissue)Deep perineal pouchPerineal membraneProstatic sinuses Fig. 5.46 Ultrasound demonstrating the bladder. A. Full bladder. B. Postmicturition bladder. Fig. 5.47 Reproductive system in men. A. Overview. B. Testis and surrounding structures. External iliac arteryUreterProstateInferiorepigastricarteryAmpulla of ductusdeferensDeep inguinalringSuperficial inguinal ringInguinal canalSpermatic cordTestisTail of epididymisHead of epididymisBody of epididymisTunica vaginalisMusculofascial pouchDuctus deferensDuctus deferensBulbo-urethral gland in deep perineal pouchSeminal vesicleEjaculatory ductsScrotumA


Anatomy_Gray

Anatomy_Gray. Capsule(tunica albuginea)Seminiferous tubuleLigamentous remnantof processus vaginalisBParietal layerCavityTunicavaginalisVisceral layerEfferent ductulesHead of epididymisDuctus deferensBody of epididymisRete testis in mediastinum testisTail of epididymisStraight tubule Fig. 5.48 The prostate gland. Zonal anatomy. Seminal vesicleArea of seminalcolliculusExternal urethralsphincterEjaculatory ductTransitionalzoneUrethraPeripheral zoneCentral zoneAnterior region(nonglandular)Penile urethraAmpulla of ductusdeferens Fig. 5.49 Axial T2-weighted magnetic resonance images of prostate problems. A. A small prostatic cancer in the peripheral zone of a normal-sized prostate. B. Benign prostatic hypertrophy. Fig. 5.50 Reproductive system in women. Glans clitorisBladderOvaryVaginaUterine tubeLigament of ovaryRound ligamentof uterusDeep inguinal ringSuperficial inguinal ringGreater vestibularglandBulb of vestibuleUterus Fig. 5.51 Ovaries and broad ligament.


Anatomy_Gray

Anatomy_Gray. Fig. 5.51 Ovaries and broad ligament. Ovarian vesselsMesovariumSuspensory ligamentof ovaryRound ligamentof the uterusLigament of ovaryInguinal canalLabium majorusDeep inguinal ringSuperficial inguinal ring Fig. 5.52 Sagittal magnetic resonance image demonstrating ovarian cancer. Fig. 5.53 Uterus. Anterior view. The anterior halves of the uterus and vagina have been cut away. BodyFundusVaginaOpening of uterine tubeUterine tubeCervix Fig. 5.54 Uterine tubes. AmpullaIsthmusOvaryAnteriorPosteriorMedialLateralFundus of uterusInfundibulumFimbriaeOpening of theuterine tubeRound ligamentof uterusLigament of ovary Fig. 5.55 Uterus and vagina. A. Angles of anteflexion and anteversion. B. The cervix protrudes into the vagina. Anterior fornixVaginal canalAngle of anteversionAngle ofanteflexionAxis ofuterinebodyABPosteriorfornixInternal osExternal osAxis of cervixAxis of vagina


Anatomy_Gray

Anatomy_Gray. Anterior fornixVaginal canalAngle of anteversionAngle ofanteflexionAxis ofuterinebodyABPosteriorfornixInternal osExternal osAxis of cervixAxis of vagina Fig. 5.56 Picture taken through a speculum inserted into the vagina demonstrating cervical cancer. See Fig. 5.84E on p. 519 for a view of the normal cervix. Fig. 5.57 Vagina. A. Left half of pelvis cut away. B. Vaginal fornices and cervix as viewed through a speculum. Lateral fornixBladderABPosterior fornixLateral fornixCervixAnterior fornixBlade of speculumBlade of speculumVaginal vaultVaginaExternal vaginal openingUterusRectumRound ligamentof uterus Fig. 5.58 Pelvic fascia. A. In women. B. In men. Anal canalProstateProstatic plexus of veinsPuboprostatic ligamentRectumProstatic fasciaRectovesicalseptumB A Transverse cervical ligamentPubocervical ligamentUterosacral ligamentRectovaginal septum Fig. 5.59 Peritoneum in the pelvis. A. In women. B. In men.


Anatomy_Gray

Anatomy_Gray. Fig. 5.59 Peritoneum in the pelvis. A. In women. B. In men. Inferior epigastricarteryBroad ligamentVesico-uterine pouchLateral umbilical foldMedial umbilical foldLigament of ovaryMedian umbilical foldRecto-uterine pouchRecto-uterine foldUreterRound ligamentof uterusSuspensoryligamentof ovaryAUterine tubeMesosalpinxBroad ligamentOvarian surface(germinal)epitheliumRound ligamentof uterusOvaryUreterUterine arterySagittal section of broad ligamentMesovariumMesometrium Fig. 5.60 Sacral and coccygeal plexuses.


Anatomy_Gray

Anatomy_Gray. Fig. 5.60 Sacral and coccygeal plexuses. Lumbosacral trunkSuperior gluteal nerveInferior gluteal nerveNerve to piriformis muscleObturator nerve(from lumbar plexus)Sciatic nervePosterior femoralcutaneous nervePudendal nervePerforatingcutaneous nerveNerves to coccygeus,levator ani, and externalanal sphincter musclesAnococcygeal nervesCoccygeal plexusL4L5S1S2S3S4Pelvic splanchnic nerves (parasympathetics from S2 to S4)Nerve to obturatorinternus and superiorgemellus musclesNerve to quadratusfemoris and inferiorgemellus muscles Fig. 5.61 Components and branches of the sacral and coccygeal plexuses.


Anatomy_Gray

Anatomy_Gray. Fig. 5.61 Components and branches of the sacral and coccygeal plexuses. L4L5S1Sciatic nerveTo obturator internus muscleTo quadratus femoris andinferior gemellus musclesPudendal nervePelvic splanchnic nervesPelvic splanchnicnervePosterior femoral cutaneous nervePerforating cutaneous nerveInferior glutealSuperior glutealLumbosacral trunkCommon fibular partTibial partS2S3S4S5CoTo piriformis muscleAnococcygeal nervesVentral divisionsDorsal divisionsAnterior ramiCoccygeal plexusTo levator ani, coccygeus, and external anal sphincter musclesSacral plexus Fig. 5.62 Sympathetic trunks in the pelvis. Gray ramus communicansSympathetic trunksGanglion imparSacral splanchnicnerves to inferiorhypogastric plexus Fig. 5.63 Pelvic extensions of the prevertebral plexus. A. Anterior view. B. Anteromedial view of right side of plexus.


Anatomy_Gray

Anatomy_Gray. Fig. 5.63 Pelvic extensions of the prevertebral plexus. A. Anterior view. B. Anteromedial view of right side of plexus. L5S1S2S3S4Pelvic splanchnic nerves(parasympatheticsfrom S2 to S4)Sacral splanchnic nervesGray ramicommunicantesSympathetictrunkHypogastric nerveGanglionimparSuperior hypogastric plexusInferior hypogastricplexusPelvic parasympathetics ascendingSympathetics descendingA Fig. 5.64 Branches of the posterior trunk of the internal iliac artery. Fig. 5.65 Branches of the anterior trunk of the internal iliac artery. A. Male. B. Female. S1S2S3S4Median sacral artery (from aorta in abdomen)Internal iliac arteryAnterior trunk of internal iliac arteryDorsal artery of penisObturator arterySuperior vesical arteryInferior vesical arteryInferior gluteal arteryInternal pudendal arteryMiddle rectal artery Umbilical arteryA Fig. 5.66 Uterine and vaginal arteries.


Anatomy_Gray

Anatomy_Gray. Fig. 5.66 Uterine and vaginal arteries. Fig. 5.67 Pelvic veins. A. In a man with the left side of the pelvis and most of the viscera removed. B. Veins associated with the rectum and anal canal. Internal iliac veinMedian sacral veinMedian sacral veinObturator veinInternal pudendal veinMiddle rectal veinVesical plexusProstatic plexus of veinsAInternal pudendal veinMiddle rectal veinInferior rectal veinSuperior rectal veinTo hepatic portal systemTo caval systemTo caval systemAnal canalPelvic floorRectumBExternal venous plexusInternal rectalplexus Fig. 5.68 Pelvic lymphatics. Fig. 5.69 Borders and ceiling of the perineum. A. Boundaries of the perineum. B. Perineal membrane. Fig. 5.70 Ischio-anal fossae and their anterior recesses. A. Anterolateral view with left pelvic wall removed. B. Inferior view. C. Anterolateral view with pelvic walls and diaphragm removed.


Anatomy_Gray

Anatomy_Gray. Fig. 5.70 Ischio-anal fossae and their anterior recesses. A. Anterolateral view with left pelvic wall removed. B. Inferior view. C. Anterolateral view with pelvic walls and diaphragm removed. Obturator internus muscleIschio-anal fossaeAnterior recesses of ischio-anal fossaeSacrotuberous ligamentSacrospinous ligamentCoccygeus muscleAObturator internus muscleTendon of obturatorinternus muscleIschio-anal fossaeAnterior recesses of ischio-anal fossaeBObturator internus muscleAnterior recesses of ischio-anal fossaeLevator aniCDeep perineal pouchDeep perineal pouchPerineal membranePerineal membrane Fig. 5.71 Erectile tissues of clitoris and penis. A. Clitoris. B. Penis.


Anatomy_Gray

Anatomy_Gray. Fig. 5.71 Erectile tissues of clitoris and penis. A. Clitoris. B. Penis. Corpora cavernosaGlans penisExternal urethralorificeNavicular fossaof urethraCrus of penis(attached part ofcorpus cavernosum)Crus of clitoris(attached part ofcorpus cavernosum)Corpora cavernosaCorpus spongiosumcontaining urethraBody of clitoris(cross section)Body of penis(cross section)Bulb of vestibuleBulb of penis(attached part ofcorpus spongiosum)Glans clitorisGreater vestibular glandin superficial pouchBulbo-urethral glandwithin deep pouchSkinAB Fig. 5.72 Muscles in the superficial perineal pouch. A. In women. B. In men. Midline rapheIschiocavernosus muscleBulbospongiosusmusclePerineal bodySuperficial transverse perineal muscleFundiform ligament of penisSuspensory ligament of penisIschiocavernosus muscleBulbospongiosusmusclePerineal bodySuperficial transverse perineal muscleSuspensory ligament of clitorisAB


Anatomy_Gray

Anatomy_Gray. Fig. 5.73 Superficial features of the perineum in women. A. Overview. B. Close-up of external genitalia. Ischial tuberosity(palpable)Urogenital triangleABMons pubisAnal triangleUrethral openingVestibule(between labia minora)Vaginal openingPubic symphysis(palpable)Coccyx(palpable)Anal aperturePosterior commissureOpening of duct ofparaurethral glandFrenulumPrepuce of clitorisGlans clitorisLateral foldMedial foldLabium minusHymenFourchetteOpening of duct ofgreater vestibular gland Fig. 5.74 Superficial features of the perineum in men. A. Overview. B. Close-up of external genitalia. Ischial tuberosity(palpable)Urogenital triangleSkin overlying spermatic cordSkin overlyingbulb of penisAnal trianglePubic symphysis(palpable)Coccyx(palpable)Anal apertureRapheScrotumFrenulum of glansExternal urethral orificeGlans penisPrepuceNeck of glansCorona of glansAB Fig. 5.75 Superficial fascia. A. Lateral view. B. Anterior view.