Anatomy_Gray

Anatomy_Gray. The ischiofemoral ligament reinforces the posterior aspect of the fibrous membrane (Fig. 6.33C). It is attached medially to the ischium, just posteroinferior to the acetabulum, and laterally to the greater trochanter deep to the iliofemoral ligament. The fibers of all three ligaments are oriented in a spiral fashion around the hip joint so that they become taut when the joint is extended. This stabilizes the joint and reduces the amount of muscle energy required to maintain a standing position. Vascular supply to the hip joint is predominantly through branches of the obturator artery, medial and lateral circumflex femoral arteries, superior and inferior gluteal arteries, and the first perforating branch of the deep artery of the thigh. The articular branches of these vessels form a network around the joint (Fig. 6.34). The hip joint is innervated by articular branches from the femoral, obturator, and superior gluteal nerves, and the nerve to the quadratus femoris.


Anatomy_Gray

Anatomy_Gray. The hip joint is innervated by articular branches from the femoral, obturator, and superior gluteal nerves, and the nerve to the quadratus femoris. Gateways to the lower limb There are four major routes by which structures pass from the abdomen and pelvis into and out of the lower limb. These are the obturator canal, the greater sciatic foramen, the lesser sciatic foramen, and the gap between the inguinal ligament and the anterosuperior margin of the pelvis (Fig. 6.35). The obturator canal is an almost vertically oriented passageway at the anterosuperior edge of the obturator foramen (Fig. 6.35). It is bordered: above by a groove (obturator groove) on the inferior surface of the superior ramus of the pubic bone, and below by the upper margin of the obturator membrane, which fills most of the obturator foramen, and by muscles (obturator internus and externus) attached to the inner and outer surfaces of the obturator membrane and surrounding bone.


Anatomy_Gray

Anatomy_Gray. The obturator canal connects the abdominopelvic region with the medial compartment of the thigh. The obturator nerve and vessels pass through the canal. The greater sciatic foramen is formed on the posterolateral pelvic wall and is the major route for structures to pass between the pelvis and the gluteal region of the lower limb (Fig. 6.35). The margins of the foramen are formed by: the greater sciatic notch, parts of the upper borders of the sacrospinous and sacrotuberous ligaments, and the lateral border of the sacrum. The piriformis muscle passes out of the pelvis into the gluteal region through the greater sciatic foramen and separates the foramen into two parts, a part above the muscle and a part below: The superior gluteal nerve and vessels pass through the greater sciatic foramen above the piriformis.


Anatomy_Gray

Anatomy_Gray. The superior gluteal nerve and vessels pass through the greater sciatic foramen above the piriformis. The sciatic nerve, inferior gluteal nerve and vessels, pudendal nerve and internal pudendal vessels, posterior cutaneous nerve of the thigh, nerve to the obturator internus and gemellus superior, and nerve to the quadratus femoris and gemellus inferior pass through the greater sciatic foramen below the muscle. The lesser sciatic foramen is inferior to the greater sciatic foramen on the posterolateral pelvic wall (Fig. 6.35). It is also inferior to the lateral attachment of the pelvic floor (levator ani and coccygeus muscles) to the pelvic wall and therefore connects the gluteal region with the perineum: The tendon of the obturator internus passes from the lateral pelvic wall through the lesser sciatic foramen into the gluteal region to insert on the femur.


Anatomy_Gray

Anatomy_Gray. The tendon of the obturator internus passes from the lateral pelvic wall through the lesser sciatic foramen into the gluteal region to insert on the femur. The pudendal nerve and internal pudendal vessels, which first exit the pelvis by passing through the greater sciatic foramen below the piriformis muscle, enter the perineum below the pelvic floor by passing around the ischial spine and sacrospinous ligament and medially through the lesser sciatic foramen. Gap between the inguinal ligament


Anatomy_Gray

Anatomy_Gray. Gap between the inguinal ligament The large crescent-shaped gap between the inguinal ligament above and the anterosuperior margin of the pelvic bone below is the major route of communication between the abdomen and the anteromedial aspect of the thigh (Fig. 6.35). The psoas major, iliacus, and pectineus muscles pass through this gap to insert onto the femur. The major blood vessels (femoral artery and vein) and lymphatics of the lower limb also pass through it, as does the femoral nerve, to enter the femoral triangle of the thigh. Nerves that enter the lower limb from the abdomen and pelvis are terminal branches of the lumbosacral plexus on the posterior wall of the abdomen and the posterolateral walls of the pelvis (Fig. 6.36 and Table 6.1).


Anatomy_Gray

Anatomy_Gray. The lumbar plexus is formed by the anterior rami of spinal nerves L1 to L3 and part of L4 (see Chapter 4, pp. 398–401). The rest of the anterior ramus of L4 and the anterior ramus of L5 combine to form the lumbosacral trunk, which enters the pelvic cavity and joins with the anterior rami of S1 to S3 and part of S4 to form the sacral plexus (see Chapter 5, pp. 480–486). Major nerves that originate from the lumbosacral plexus and leave the abdomen and pelvis to enter the lower limb include the femoral nerve, obturator nerve, sciatic nerve, superior gluteal nerve, and inferior gluteal nerve. Other nerves that also originate from the plexus and enter the lower limb to supply skin or muscle include the lateral cutaneous nerve of the thigh, nerve to the obturator internus, nerve to the quadratus femoris, posterior cutaneous nerve of the thigh, perforating cutaneous nerve, and branches of the ilio-inguinal and genitofemoral nerves.


Anatomy_Gray

Anatomy_Gray. The femoral nerve carries contributions from the anterior rami of L2 to L4 and leaves the abdomen by passing through the gap between the inguinal ligament and superior margin of the pelvis to enter the femoral triangle on the anteromedial aspect of the thigh (Fig. 6.35 and Table 6.1). In the femoral triangle it is lateral to the femoral artery. The femoral nerve: innervates all muscles in the anterior compartment of the thigh, in the abdomen, gives rise to branches that innervate the iliacus and pectineus muscles, and innervates skin over the anterior aspect of the thigh, the anteromedial side of the knee, the medial side of the leg, and the medial side of the foot.


Anatomy_Gray

Anatomy_Gray. The obturator nerve, like the femoral nerve, originates from L2 to L4. It descends along the posterior abdominal wall, passes through the pelvic cavity and enters the thigh by passing through the obturator canal (Fig. 6.36 and Table 6.1). The obturator nerve innervates: all muscles in the medial compartment of the thigh, except the part of the adductor magnus muscle that originates from the ischium and the pectineus muscle, which are innervated by the sciatic and the femoral nerves, respectively; the obturator externus muscle; and skin on the medial side of the upper thigh. The sciatic nerve is the largest nerve of the body and carries contributions from L4 to S3. It leaves the pelvis through the greater sciatic foramen inferior to the piriformis muscle, enters and passes through the gluteal region (Fig. 6.36 and Table 6.1), and then enters the posterior compartment of the thigh where it divides into its two major branches: the common fibular nerve, and the tibial nerve.


Anatomy_Gray

Anatomy_Gray. Posterior divisions of L4 to S2 are carried in the common fibular part of the nerve and the anterior divisions of L4 to S3 are carried in the tibial part. The sciatic nerve innervates: all muscles in the posterior compartment of the thigh, the part of the adductor magnus originating from the ischium, all muscles in the leg and foot, and skin on the lateral side of the leg and the lateral side and sole of the foot. The gluteal nerves are major motor nerves of the gluteal region. The superior gluteal nerve (Fig. 6.36 and Table 6.1) carries contributions from the anterior rami of L4 to S1, leaves the pelvis through the greater sciatic foramen above the piriformis muscle, and innervates: the gluteus medius and minimus muscles, and the tensor fasciae latae muscle.


Anatomy_Gray

Anatomy_Gray. The inferior gluteal nerve (Fig. 6.36 and Table 6.1) is formed by contributions from L5 to S2, leaves the pelvis through the greater sciatic foramen inferior to the piriformis muscle, and enters the gluteal region to supply the gluteus maximus. Terminal sensory branches of the ilio-inguinal nerve (L1) and the genitofemoral nerve (L1, L2) descend into the upper thigh from the lumbar plexus. The ilio-inguinal nerve originates from the superior part of the lumbar plexus, descends around the abdominal wall in the plane between the transversus abdominis and internal oblique muscles, and then passes through the inguinal canal to leave the abdominal wall through the superficial inguinal ring (Fig. 6.36 and Table 6.1). Its terminal branches innervate skin on the medial side of the upper thigh and adjacent parts of the perineum.


Anatomy_Gray

Anatomy_Gray. The genitofemoral nerve passes anteroinferiorly through the psoas major muscle on the posterior abdominal wall and descends on the anterior surface of the psoas major (Fig. 6.36 and Table 6.1). Its genital branch innervates anterior aspects of the perineum. Its femoral branch passes into the thigh by crossing under the inguinal ligament where it is lateral to the femoral artery. It passes superficially to innervate skin over the upper central part of the anterior thigh. Lateral cutaneous nerve of thigh The lateral cutaneous nerve of the thigh originates from L2 and L3. It leaves the abdomen either by passing through the gap between the inguinal ligament and the pelvic bone just medial to the anterior superior iliac spine or by passing directly through the inguinal ligament (Fig. 6.36 and Table 6.1). It supplies skin on the lateral side of the thigh. Nerve to quadratus femoris and nerve


Anatomy_Gray

Anatomy_Gray. Nerve to quadratus femoris and nerve The nerve to the quadratus femoris (L4 to S1) and the nerve to the obturator internus (L5 to S2) are small motor nerves that originate from the sacral plexus. Both nerves pass through the greater sciatic foramen inferior to the piriformis muscle and enter the gluteal region (Fig. 6.36 and Table 6.1): The nerve to the obturator internus supplies the gemellus superior muscle in the gluteal region and then loops around the ischial spine and enters the perineum through the lesser sciatic foramen to penetrate the perineal surface of the obturator internus muscle. The nerve to the quadratus femoris supplies the gemellus inferior and quadratus femoris muscles. Posterior cutaneous nerve of thigh


Anatomy_Gray

Anatomy_Gray. The nerve to the quadratus femoris supplies the gemellus inferior and quadratus femoris muscles. Posterior cutaneous nerve of thigh The posterior cutaneous nerve of the thigh is formed by contributions from S1 to S3 and leaves the pelvic cavity through the greater sciatic foramen inferior to the piriformis muscle (Fig. 6.36 and Table 6.1). It passes vertically through the gluteal region deep to the gluteus maximus and enters the posterior thigh and innervates: a longitudinal band of skin over the posterior aspect of the thigh that continues into the upper leg, and skin over the gluteal fold, over the upper medial part of the thigh and in the adjacent regions of the perineum.


Anatomy_Gray

Anatomy_Gray. The perforating cutaneous nerve is a small sensory nerve formed by contributions from S2 and S3. It leaves the pelvic cavity by penetrating directly through the sacrotuberous ligament (Fig. 6.36 and Table 6.1) and passes inferiorly around the lower border of the gluteus maximus where it overlaps with the posterior cutaneous nerve of the thigh in innervating skin over the medial aspect of the gluteal fold. The major artery supplying the lower limb is the femoral artery (Fig. 6.37), which is the continuation of the external iliac artery in the abdomen. The external iliac artery becomes the femoral artery as the vessel passes under the inguinal ligament to enter the femoral triangle in the anterior aspect of the thigh. Branches supply most of the thigh and all of the leg and foot. the obturator artery Other vessels supplying parts of the lower limb include the superior and inferior gluteal arteries and the obturator artery (Fig. 6.37).


Anatomy_Gray

Anatomy_Gray. the obturator artery Other vessels supplying parts of the lower limb include the superior and inferior gluteal arteries and the obturator artery (Fig. 6.37). The superior and inferior gluteal arteries originate in the pelvic cavity as branches of the internal iliac artery (see Chapter 5, pp. 489–492) and supply the gluteal region. The superior gluteal artery leaves the pelvis through the greater sciatic foramen above the piriformis muscle, and the inferior gluteal artery leaves through the same foramen but below the piriformis muscle. The obturator artery is also a branch of the internal iliac artery in the pelvic cavity (see Chapter 5, pp. 490–491) and passes through the obturator canal to enter and supply the medial compartment of the thigh.


Anatomy_Gray

Anatomy_Gray. Branches of the femoral, inferior gluteal, superior gluteal, and obturator arteries, together with branches from the internal pudendal artery of the perineum, interconnect to form an anastomotic network in the upper thigh and gluteal region. The presence of these anastomotic channels may provide collateral circulation when one of the vessels is interrupted. Veins draining the lower limb form superficial and deep groups. The deep veins generally follow the arteries (femoral, superior gluteal, inferior gluteal, and obturator). The major deep vein draining the limb is the femoral vein (Fig. 6.38). It becomes the external iliac vein when it passes under the inguinal ligament to enter the abdomen.


Anatomy_Gray

Anatomy_Gray. The superficial veins are in the subcutaneous connective tissue and are interconnected with and ultimately drain into the deep veins. The superficial veins form two major channels—the great saphenous vein and the small saphenous vein. Both veins originate from a dorsal venous arch in the foot: The great saphenous vein originates from the medial side of the dorsal venous arch and then ascends up the medial side of the leg, knee, and thigh to connect with the femoral vein just inferior to the inguinal ligament. The small saphenous vein originates from the lateral side of the dorsal venous arch, ascends up the posterior surface of the leg, and then penetrates deep fascia to join the popliteal vein posterior to the knee; proximal to the knee, the popliteal vein becomes the femoral vein. Most lymphatic vessels in the lower limb drain into superficial and deep inguinal nodes located in the fascia just inferior to the inguinal ligament (Fig. 6.39).


Anatomy_Gray

Anatomy_Gray. Most lymphatic vessels in the lower limb drain into superficial and deep inguinal nodes located in the fascia just inferior to the inguinal ligament (Fig. 6.39). The superficial inguinal nodes, approximately ten in number, are in the superficial fascia and parallel the course of the inguinal ligament in the upper thigh. Medially, they extend inferiorly along the terminal part of the great saphenous vein. Superficial inguinal nodes receive lymph from the gluteal region, lower abdominal wall, perineum, and superficial regions of the lower limb. They drain, via vessels that accompany the femoral vessels, into external iliac nodes associated with the external iliac artery in the abdomen. The deep inguinal nodes, up to three in number, are medial to the femoral vein (Fig. 6.39).


Anatomy_Gray

Anatomy_Gray. The deep inguinal nodes, up to three in number, are medial to the femoral vein (Fig. 6.39). The deep inguinal nodes receive lymph from deep lymphatics associated with the femoral vessels and from the glans penis (or clitoris) in the perineum. They interconnect with the superficial inguinal nodes and drain into the external iliac nodes via vessels that pass along the medial side of the femoral vein as it passes under the inguinal ligament. The space through which the lymphatic vessels pass under the inguinal ligament is the femoral canal. In addition to the inguinal nodes, there is a small collection of deep nodes posterior to the knee close to the popliteal vessels (Fig. 6.39). These popliteal nodes receive lymph from superficial vessels, which accompany the small saphenous vein, and from deep areas of the leg and foot. They ultimately drain into the deep and superficial inguinal nodes. Deep fascia and the saphenous opening


Anatomy_Gray

Anatomy_Gray. Deep fascia and the saphenous opening The outer layer of deep fascia in the lower limb forms a thick “stocking-like” membrane, which covers the limb and lies beneath the superficial fascia (Fig. 6.40A). This deep fascia is particularly thick in the thigh and gluteal region and is termed the fascia lata. The fascia lata is anchored superiorly to bone and soft tissues along a line of attachment that defines the upper margin of the lower limb. Beginning anteriorly and circling laterally around the limb, this line of attachment includes the inguinal ligament, iliac crest, sacrum, coccyx, sacrotuberous ligament, inferior ramus of the pubic bone, body of the pubic bone, and superior ramus of the pubic bone. Inferiorly, the fascia lata is continuous with the deep fascia of the leg.


Anatomy_Gray

Anatomy_Gray. Inferiorly, the fascia lata is continuous with the deep fascia of the leg. The fascia lata is thickened laterally into a longitudinal band (the iliotibial tract), which descends along the lateral margin of the limb from the tuberculum of the iliac crest to a bony attachment just below the knee (Fig. 6.40B). The superior aspect of the fascia lata in the gluteal region splits anteriorly to enclose the tensor fasciae latae muscle and posteriorly to enclose the gluteus maximus muscle: The tensor fasciae latae muscle is partially enclosed by and inserts into the superior and anterior aspects of the iliotibial tract. Most of the gluteus maximus muscle inserts into the posterior aspect of the iliotibial tract.


Anatomy_Gray

Anatomy_Gray. Most of the gluteus maximus muscle inserts into the posterior aspect of the iliotibial tract. The tensor fasciae latae and gluteus maximus muscles, working through their attachments to the iliotibial tract, hold the leg in extension once other muscles have extended the leg at the knee joint. The iliotibial tract and its two associated muscles also stabilize the hip joint by preventing lateral displacement of the proximal end of the femur away from the acetabulum. The fascia lata has one prominent aperture on the anterior aspect of the thigh just inferior to the medial end of the inguinal ligament (the saphenous opening), which allows the great saphenous vein to pass from superficial fascia through the deep fascia to connect with the femoral vein (Fig. 6.41).


Anatomy_Gray

Anatomy_Gray. The margin of the saphenous opening is formed by the free medial edge of the fascia lata as it descends from the inguinal ligament and spirals around the lateral side of the great saphenous vein and medially under the femoral vein to attach to the pectineal line (pecten pubis) of the pelvic bone. The femoral triangle is a wedge-shaped depression formed by muscles in the upper thigh at the junction between the anterior abdominal wall and the lower limb (Fig. 6.42): The base of the triangle is the inguinal ligament. The medial border is the medial margin of the adductor longus muscle in the medial compartment of the thigh. The lateral margin is the medial margin of the sartorius muscle in the anterior compartment of the thigh. The floor of the triangle is formed medially by the pectineus and adductor longus muscles in the medial compartment of the thigh and laterally by the iliopsoas muscle descending from the abdomen.


Anatomy_Gray

Anatomy_Gray. The floor of the triangle is formed medially by the pectineus and adductor longus muscles in the medial compartment of the thigh and laterally by the iliopsoas muscle descending from the abdomen. The apex of the femoral triangle points inferiorly and is continuous with a fascial canal (adductor canal), which descends medially down the thigh and posteriorly through an aperture in the lower end of one of the largest of the adductor muscles in the thigh (the adductor magnus muscle) to open into the popliteal fossa behind the knee. The femoral nerve, artery, and vein and lymphatics pass between the abdomen and lower limb under the inguinal ligament and in the femoral triangle (Fig. 6.43). The femoral artery and vein pass inferiorly through the adductor canal and become the popliteal vessels behind the knee where they meet and are distributed with branches of the sciatic nerve, which descends through the posterior thigh from the gluteal region.


Anatomy_Gray

Anatomy_Gray. From lateral to medial, major structures in the femoral triangle are the femoral nerve, the femoral artery, the femoral vein, and lymphatic vessels. The femoral artery can be palpated in the femoral triangle just inferior to the inguinal ligament and midway between the anterior superior iliac spine and the pubic symphysis.


Anatomy_Gray

Anatomy_Gray. In the femoral triangle, the femoral artery and vein and the associated lymphatic vessels are surrounded by a funnel-shaped sleeve of fascia (the femoral sheath). The sheath is continuous superiorly with the transversalis fascia and iliac fascia of the abdomen and merges inferiorly with connective tissue associated with the vessels. Each of the three structures surrounded by the sheath is contained within a separate fascial compartment within the sheath. The most medial compartment (the femoral canal) contains the lymphatic vessels and is conical in shape. The opening of this canal superiorly is potentially a weak point in the lower abdomen and is the site for femoral hernias. The femoral nerve is lateral to and not contained within the femoral sheath. The gluteal region lies posterolateral to the bony pelvis and proximal end of the femur (Fig. 6.44). Muscles in the region mainly abduct, extend, and laterally rotate the femur relative to the pelvic bone.


Anatomy_Gray

Anatomy_Gray. The gluteal region communicates anteromedially with the pelvic cavity and perineum through the greater sciatic foramen and lesser sciatic foramen, respectively. Inferiorly, it is continuous with the posterior thigh. The sciatic nerve enters the lower limb from the pelvic cavity by passing through the greater sciatic foramen and descending through the gluteal region into the posterior thigh and then into the leg and foot. The pudendal nerve and internal pudendal vessels pass between the pelvic cavity and perineum by passing first through the greater sciatic foramen to enter the gluteal region and then immediately passing through the lesser sciatic foramen to enter the perineum. The nerve to the obturator internus and gemellus superior follows a similar course. Other nerves and vessels that pass through the greater sciatic foramen from the pelvic cavity supply structures in the gluteal region itself.


Anatomy_Gray

Anatomy_Gray. Muscles of the gluteal region (Table 6.2) are composed mainly of two groups: a deep group of small muscles, which are mainly lateral rotators of the femur at the hip joint and include the piriformis, obturator internus, gemellus superior, gemellus inferior, and quadratus femoris; a more superficial group of larger muscles, which mainly abduct and extend the hip and include the gluteus minimus, gluteus medius, and gluteus maximus; an additional muscle in this group, the tensor fasciae latae, stabilizes the knee in extension by acting on a specialized longitudinal band of deep fascia (the iliotibial tract) that passes down the lateral side of the thigh to attach to the proximal end of the tibia in the leg. Many of the important nerves in the gluteal region are in the plane between the superficial and deep groups of muscles.


Anatomy_Gray

Anatomy_Gray. Many of the important nerves in the gluteal region are in the plane between the superficial and deep groups of muscles. The piriformis muscle is the most superior of the deep group of muscles (Fig. 6.45) and is a muscle of the pelvic wall and of the gluteal region (see Chapter 5, p. 443). It originates from between the anterior sacral foramina on the anterolateral surface of the sacrum and passes laterally and inferiorly through the greater sciatic foramen. In the gluteal region, the piriformis passes posterior to the hip joint and attaches to a facet on the upper margin of the greater trochanter of the femur. The piriformis externally rotates and abducts the femur at the hip joint and is innervated in the pelvic cavity by the nerve to the piriformis, which originates as branches from S1 and S2 of the sacral plexus (see Chapter 5, p. 485).


Anatomy_Gray

Anatomy_Gray. In addition to its action on the hip joint, the piriformis is an important landmark because it divides the greater sciatic foramen into two regions, one above and one below the piriformis. Vessels and nerves pass between the pelvis and gluteal region by passing through the greater sciatic foramen either above or below the piriformis. The obturator internus muscle, like the piriformis muscle, is a muscle of the pelvic wall and of the gluteal region (Fig. 6.45). It is a flat fan-shaped muscle originating from the medial surface of the obturator membrane and adjacent bone of the obturator foramen (see Chapter 5, pp. 442–443). Because the pelvic floor attaches to a thickened band of fascia across the medial surface of the obturator internus, the obturator internus forms: the anterolateral wall of the pelvic cavity above the pelvic floor, and the lateral wall of the ischio-anal fossa in the perineum below the pelvic floor.


Anatomy_Gray

Anatomy_Gray. The muscle fibers of the obturator internus converge to form a tendon, which bends 90° around the ischium between the ischial spine and ischial tuberosity and passes through the lesser sciatic foramen to enter the gluteal region. The tendon then passes posteroinferiorly to the hip joint and attaches to the medial surface of the superior margin of the greater trochanter of the femur just inferior to the attachment of the piriformis muscle. The obturator internus laterally rotates and abducts the femur at the hip joint and is innervated by the nerve to the obturator internus. The gemellus superior and inferior (gemelli is Latin for “twins”) are a pair of triangular muscles associated with the upper and lower margins of the obturator internus tendon (Fig. 6.45): The base of the gemellus superior originates from the gluteal surface of the ischial spine. The base of the gemellus inferior originates from the upper gluteal and pelvic surfaces of the ischial tuberosity.


Anatomy_Gray

Anatomy_Gray. The base of the gemellus inferior originates from the upper gluteal and pelvic surfaces of the ischial tuberosity. Fibers of the gemellus muscles attach along the length of the obturator internus tendon, and the apices of the two muscles insert with the tendon of the obturator internus on the greater trochanter of the femur. The gemellus superior is innervated by the nerve to the obturator internus, and the gemellus inferior is innervated by the nerve to the quadratus femoris. The gemellus muscles act with the obturator internus muscle to laterally rotate and abduct the femur at the hip joint. The quadratus femoris muscle is the most inferior of the deep group of muscles in the gluteal region (Fig. 6.45). It is a flat rectangular muscle below the obturator internus muscle and its associated gemellus muscles.


Anatomy_Gray

Anatomy_Gray. The quadratus femoris is attached at one end to a linear roughening on the lateral aspect of the ischium just anterior to the ischial tuberosity and at the other end to the quadrate tubercle on the intertrochanteric crest of the proximal femur. The quadratus femoris laterally rotates the femur at the hip joint and is innervated by the nerve to the quadratus femoris. The gluteus minimus and medius muscles are two muscles of the more superficial group in the gluteal region (Fig. 6.45). The gluteus minimus is a fan-shaped muscle that originates from the external surface of the expanded upper part of the ilium, between the inferior gluteal line and the anterior gluteal line. The muscle fibers converge inferiorly and laterally to form a tendon, which inserts into a broad linear facet on the anterolateral aspect of the greater trochanter.


Anatomy_Gray

Anatomy_Gray. The gluteus medius overlies the gluteus minimus and is also fan shaped. It has a broad origin from the external surface of the ilium between the anterior gluteal line and posterior gluteal line and inserts on an elongate facet on the lateral surface of the greater trochanter. The gluteus medius and minimus muscles abduct the lower limb at the hip joint and reduce pelvic drop over the opposite swing limb during walking by securing the position of the pelvis on the stance limb (Fig. 6.45B). Both muscles are innervated by the superior gluteal nerve. The gluteus maximus is the largest muscle in the gluteal region and overlies most of the other gluteal muscles (Fig. 6.46).


Anatomy_Gray

Anatomy_Gray. The gluteus maximus is the largest muscle in the gluteal region and overlies most of the other gluteal muscles (Fig. 6.46). The gluteus maximus is quadrangular in shape and has a broad origin extending from a roughened area of the ilium behind the posterior gluteal line and along the dorsal surface of the lower sacrum and the lateral surface of the coccyx to the external surface of the sacrotuberous ligament. It is also attached to fascia overlying the gluteus medius muscle and, between the ilium and sacrum, to fascia covering the erector spinae muscle, and is often described as being enclosed within two layers of the fascia lata, which covers the thigh and gluteal region.


Anatomy_Gray

Anatomy_Gray. Laterally, the upper and superficial lower parts of the gluteus maximus insert into the posterior aspect of a tendinous thickening of the fascia lata (the iliotibial tract), which passes over the lateral surface of the greater trochanter and descends down the thigh and into the upper leg. Deep distal parts of the muscle attach to the elongate gluteal tuberosity of the proximal femur. The gluteus maximus mainly extends the flexed thigh at the hip joint. Through its insertion into the iliotibial tract, it also stabilizes the knee and hip joints. It is innervated by the inferior gluteal nerve. The tensor fasciae latae muscle is the most anterior of the superficial group of muscles in the gluteal region and overlies the gluteus minimus and the anterior part of the gluteus medius (Fig. 6.47).


Anatomy_Gray

Anatomy_Gray. The tensor fasciae latae originates from the outer margin of the iliac crest from the anterior superior iliac spine to approximately the tuberculum of the iliac crest. The muscle fibers descend to insert into the anterior aspect of the iliotibial tract of deep fascia, which runs down the lateral side of the thigh and attaches to the upper tibia. Like the gluteus maximus muscle, the tensor fasciae latae is enclosed within a compartment of the fascia lata. The tensor fasciae latae stabilizes the knee in extension and, working with the gluteus maximus muscle on the iliotibial tract lateral to the greater trochanter, stabilizes the hip joint by holding the head of the femur in the acetabulum (Fig. 6.47). It is innervated by the superior gluteal nerve.


Anatomy_Gray

Anatomy_Gray. Seven nerves enter the gluteal region from the pelvis through the greater sciatic foramen (Fig. 6.48): the superior gluteal nerve, sciatic nerve, nerve to the quadratus femoris, nerve to the obturator internus, posterior cutaneous nerve of the thigh, pudendal nerve, and inferior gluteal nerve. An additional nerve, the perforating cutaneous nerve, enters the gluteal region by passing directly through the sacrotuberous ligament. Some of these nerves, such as the sciatic and pudendal nerves, pass through the gluteal region en route to other areas. Nerves such as the superior and inferior gluteal nerves innervate structures in the gluteal region. Many of the nerves in the gluteal region are in the plane between the superficial and deep groups of muscles.


Anatomy_Gray

Anatomy_Gray. Of all the nerves that pass through the greater sciatic foramen, the superior gluteal nerve is the only one that passes above the piriformis muscle (Fig. 6.48). After entering the gluteal region, the nerve loops up over the inferior margin of the gluteus minimus and travels anteriorly and laterally in the plane between the gluteus minimus and medius muscles. The superior gluteal nerve supplies branches to the gluteus minimus and medius muscles and terminates by innervating the tensor fasciae latae muscle.


Anatomy_Gray

Anatomy_Gray. The superior gluteal nerve supplies branches to the gluteus minimus and medius muscles and terminates by innervating the tensor fasciae latae muscle. The sciatic nerve enters the gluteal region through the greater sciatic foramen inferior to the piriformis muscle (Fig. 6.48). It descends in the plane between the superficial and deep group of gluteal region muscles, crossing the posterior surfaces of first the obturator internus and associated gemellus muscles and then the quadratus femoris muscle. It lies just deep to the gluteus maximus at the midpoint between the ischial tuberosity and the greater trochanter. At the lower margin of the quadratus femoris muscle, the sciatic nerve enters the posterior thigh. The sciatic nerve is the largest nerve in the body and innervates all muscles in the posterior compartment of the thigh that flex the knee and all muscles that work the ankle and foot. It also innervates a large area of skin in the lower limb. Nerve to quadratus femoris


Anatomy_Gray

Anatomy_Gray. Nerve to quadratus femoris The nerve to the quadratus femoris enters the gluteal region through the greater sciatic foramen inferior to the piriformis muscle and deep to the sciatic nerve (Fig. 6.48). Unlike other nerves in the gluteal region, the nerve to the quadratus femoris lies anterior to the plane of the deep muscles. The nerve to the quadratus femoris descends along the ischium deep to the tendon of the obturator internus muscle and associated gemellus muscles to penetrate and innervate the quadratus femoris. It supplies a small branch to the gemellus inferior. Nerve to obturator internus


Anatomy_Gray

Anatomy_Gray. Nerve to obturator internus The nerve to the obturator internus enters the gluteal region through the greater sciatic foramen inferior to the piriformis muscle and between the posterior cutaneous nerve of the thigh and the pudendal nerve (Fig. 6.48). It supplies a small branch to the gemellus superior and then passes over the ischial spine and through the lesser sciatic foramen to innervate the obturator internus muscle from the medial surface of the muscle in the perineum. Posterior cutaneous nerve of the thigh The posterior cutaneous nerve of the thigh enters the gluteal region through the greater sciatic foramen inferior to the piriformis muscle and immediately medial to the sciatic nerve (Fig. 6.48). It descends through the gluteal region just deep to the gluteus maximus and enters the posterior thigh.


Anatomy_Gray

Anatomy_Gray. The posterior cutaneous nerve of the thigh has a number of gluteal branches, which loop around the lower margin of the gluteus maximus muscle to innervate skin over the gluteal fold. A small perineal branch passes medially to contribute to the innervation of the skin of the scrotum or labia majora in the perineum. The main trunk of the posterior cutaneous nerve of the thigh passes inferiorly, giving rise to branches that innervate the skin on the posterior thigh and leg. The pudendal nerve enters the gluteal region through the greater sciatic foramen inferior to the piriformis muscle and medial to the sciatic nerve (Fig. 6.48). It passes over the sacrospinous ligament and immediately passes through the lesser sciatic foramen to enter the perineum. The course of the pudendal nerve in the gluteal region is short and the nerve is often hidden by the overlying upper margin of the sacrotuberous ligament.


Anatomy_Gray

Anatomy_Gray. The pudendal nerve is the major somatic nerve of the perineum and has no branches in the gluteal region. The inferior gluteal nerve enters the gluteal region through the greater sciatic foramen inferior to the piriformis muscle and along the posterior surface of the sciatic nerve (Fig. 6.48). It penetrates and supplies the gluteus maximus muscle. The perforating cutaneous nerve is the only nerve in the gluteal region that does not enter the area through the greater sciatic foramen. It is a small nerve that leaves the sacral plexus in the pelvic cavity by piercing the sacrotuberous ligament. It then loops around the lower border of the gluteus maximus to supply the skin over the medial aspect of the gluteus maximus (Fig. 6.48).


Anatomy_Gray

Anatomy_Gray. Two arteries enter the gluteal region from the pelvic cavity through the greater sciatic foramen, the inferior gluteal artery and the superior gluteal artery (Fig. 6.50). They supply structures in the gluteal region and posterior thigh and have important collateral anastomoses with branches of the femoral artery. The inferior gluteal artery originates from the anterior trunk of the internal iliac artery in the pelvic cavity. It leaves the pelvic cavity with the inferior gluteal nerve through the greater sciatic foramen inferior to the piriformis muscle (Fig. 6.50). The inferior gluteal artery supplies adjacent muscles and descends through the gluteal region and into the posterior thigh where it supplies adjacent structures and anastomoses with perforating branches of the femoral artery. It also supplies a branch to the sciatic nerve.


Anatomy_Gray

Anatomy_Gray. The superior gluteal artery originates from the posterior trunk of the internal iliac artery in the pelvic cavity. It leaves the pelvic cavity with the superior gluteal nerve through the greater sciatic foramen above the piriformis muscle (Fig. 6.50). In the gluteal region, it divides into a superficial branch and a deep branch: The superficial branch passes onto the deep surface of the gluteus maximus muscle. The deep branch passes between the gluteus medius and minimus muscles. In addition to adjacent muscles, the superior gluteal artery contributes to the supply of the hip joint. Branches of the artery also anastomose with the lateral and medial femoral circumflex arteries from the deep femoral artery in the thigh, and with the inferior gluteal artery (Fig. 6.51).


Anatomy_Gray

Anatomy_Gray. Inferior and superior gluteal veins follow the inferior and superior gluteal arteries into the pelvis where they join the pelvic plexus of veins. Peripherally, the veins anastomose with superficial gluteal veins, which ultimately drain anteriorly into the femoral vein. Deep lymphatic vessels of the gluteal region accompany the blood vessels into the pelvic cavity and connect with internal iliac nodes. Superficial lymphatics drain into the superficial inguinal nodes on the anterior aspect of the thigh. The thigh is the region of the lower limb that is approximately between the hip and knee joints (Fig. 6.52): Anteriorly, it is separated from the abdominal wall by the inguinal ligament. Posteriorly, it is separated from the gluteal region by the gluteal fold superficially, and by the inferior margins of the gluteus maximus and quadratus femoris on deeper planes. Structures enter and leave the top of the thigh by three routes:


Anatomy_Gray

Anatomy_Gray. Structures enter and leave the top of the thigh by three routes: Posteriorly, the thigh is continuous with the gluteal region and the major structure passing between the two regions is the sciatic nerve. Anteriorly, the thigh communicates with the abdominal cavity through the aperture between the inguinal ligament and pelvic bone, and major structures passing through this aperture are the iliopsoas and pectineus muscles; the femoral nerve, artery, and vein; and lymphatic vessels. Medially, structures (including the obturator nerve and associated vessels) pass between the thigh and pelvic cavity through the obturator canal. The thigh is divided into three compartments by intermuscular septa between the posterior aspect of the femur and the fascia lata (the thick layer of deep fascia that completely surrounds or invests the thigh; Fig. 6.52C): The anterior compartment of the thigh contains muscles that mainly extend the leg at the knee joint.


Anatomy_Gray

Anatomy_Gray. The anterior compartment of the thigh contains muscles that mainly extend the leg at the knee joint. The posterior compartment of the thigh contains muscles that mainly extend the thigh at the hip joint and flex the leg at the knee joint. The medial compartment of the thigh consists of muscles that mainly adduct the thigh at the hip joint. The sciatic nerve innervates muscles in the posterior compartment of the thigh, the femoral nerve innervates muscles in the anterior compartment of the thigh, and the obturator nerve innervates most muscles in the medial compartment of the thigh. The major artery, vein, and lymphatic channels enter the thigh anterior to the pelvic bone and pass through the femoral triangle inferior to the inguinal ligament. Vessels and nerves passing between the thigh and leg pass through the popliteal fossa posterior to the knee joint.


Anatomy_Gray

Anatomy_Gray. The skeletal support for the thigh is the femur. Most of the large muscles in the thigh insert into the proximal ends of the two bones of the leg (tibia and fibula) and flex and extend the leg at the knee joint. The distal end of the femur provides origin for the gastrocnemius muscles, which are predominantly in the posterior compartment of the leg and plantarflex the foot. Shaft and distal end of femur The shaft of the femur is bowed forward and has an oblique course from the neck of the femur to the distal end (Fig. 6.53). As a consequence of this oblique orientation, the knee is close to the midline under the body’s center of gravity.


Anatomy_Gray

Anatomy_Gray. The middle part of the shaft of the femur is triangular in cross section (Fig. 6.53D). In the middle part of the shaft, the femur has smooth medial (posteromedial), lateral (posterolateral), and anterior surfaces and medial, lateral, and posterior borders. The medial and lateral borders are rounded, whereas the posterior border forms a broad roughened crest—the linea aspera. In proximal and distal regions of the femur, the linea aspera widens to form an additional posterior surface. At the distal end of the femur, this posterior surface forms the floor of the popliteal fossa, and its margins form the medial and lateral supracondylar lines. The medial supracondylar line terminates at a prominent tubercle (the adductor tubercle) on the superior aspect of the medial condyle of the distal end. Just lateral to the lower end of the medial supracondylar line is an elongate roughened area of bone for the proximal attachment of the medial head of the gastrocnemius muscle (Fig. 6.52).


Anatomy_Gray

Anatomy_Gray. The distal end of the femur is characterized by two large condyles, which articulate with the proximal head of the tibia. The condyles are separated posteriorly by an intercondylar fossa and are joined anteriorly where they articulate with the patella. The surfaces of the condyles that articulate with the tibia are rounded posteriorly and become flatter inferiorly. On each condyle, a shallow oblique groove separates the surface that articulates with the tibia from the more anterior surface that articulates with the patella. The surfaces of the medial and lateral condyles that articulate with the patella form a V-shaped trench, which faces anteriorly. The lateral surface of the trench is larger and steeper than the medial surface. The walls of the intercondylar fossa bear two facets for the superior attachment of the cruciate ligaments, which stabilize the knee joint (Fig. 6.53):


Anatomy_Gray

Anatomy_Gray. The walls of the intercondylar fossa bear two facets for the superior attachment of the cruciate ligaments, which stabilize the knee joint (Fig. 6.53): The wall formed by the lateral surface of the medial condyle has a large oval facet, which covers most of the inferior half of the wall, for attachment of the proximal end of the posterior cruciate ligament. The wall formed by the medial surface of the lateral condyle has a posterosuperior smaller oval facet for attachment of the proximal end of the anterior cruciate ligament. Epicondyles, for the attachment of collateral ligaments of the knee joint, are bony elevations on the nonarticular outer surfaces of the condyles (Fig. 6.53). Two facets separated by a groove are just posterior to the lateral epicondyle: The upper facet is for attachment of the lateral head of the gastrocnemius muscle. The inferior facet is for attachment of the popliteus muscle.


Anatomy_Gray

Anatomy_Gray. The upper facet is for attachment of the lateral head of the gastrocnemius muscle. The inferior facet is for attachment of the popliteus muscle. The tendon of the popliteus muscle lies in the groove separating the two facets. The medial epicondyle is a rounded eminence on the medial surface of the medial condyle. Just posterosuperior to the medial epicondyle is the adductor tubercle. The patella (knee cap) is the largest sesamoid bone (a bone formed within the tendon of a muscle) in the body and is formed within the tendon of the quadriceps femoris muscle as it crosses anterior to the knee joint to insert on the tibia. The patella is triangular: Its apex is pointed inferiorly for attachment to the patellar ligament, which connects the patella to the tibia (Fig. 6.54). Its base is broad and thick for the attachment of the quadriceps tendon from above.


Anatomy_Gray

Anatomy_Gray. Its base is broad and thick for the attachment of the quadriceps tendon from above. Its posterior surface articulates with the femur and has medial and lateral facets, which slope away from a raised smooth ridge—the lateral facet is larger than the medial facet for articulation with the larger corresponding surface on the lateral condyle of the femur. Proximal end of tibia The tibia is the medial and larger of the two bones in the leg, and is the only one that articulates with the femur at the knee joint. The proximal end of the tibia is expanded in the transverse plane for weight-bearing and consists of a medial condyle and a lateral condyle, which are both flattened in the horizontal plane and overhang the shaft (Fig. 6.55). The superior surfaces of the medial and lateral condyles are articular and separated by an intercondylar region, which contains sites of attachment for strong ligaments (cruciate ligaments) and interarticular cartilages (menisci) of the knee joint.


Anatomy_Gray

Anatomy_Gray. The articular surfaces of the medial and lateral condyles and the intercondylar region together form a “tibial plateau,” which articulates with and is anchored to the distal end of the femur. Inferior to the condyles on the proximal part of the shaft is a large tibial tuberosity and roughenings for muscle and ligament attachments. The tibial condyles are thick horizontal discs of bone attached to the top of the tibial shaft (Fig. 6.55). The medial condyle is larger than the lateral condyle and is better supported over the shaft of the tibia. Its superior surface is oval for articulation with the medial condyle of the femur. The articular surface extends laterally onto the side of the raised medial intercondylar tubercle. The superior surface of the lateral condyle is circular and articulates above with the lateral condyle of the femur. The medial edge of this surface extends onto the side of the lateral intercondylar tubercle.


Anatomy_Gray

Anatomy_Gray. The superior articular surfaces of both the lateral and medial condyles are concave, particularly centrally. The outer margins of the surfaces are flatter and are the regions in contact with the interarticular discs (menisci) of fibrocartilage in the knee joint. The nonarticular posterior surface of the medial condyle bears a distinct horizontal groove for part of the attachment of the semimembranosus muscle, and the undersurface of the lateral condyle bears a distinct circular facet for articulation with the proximal head of the fibula. The intercondylar region of the tibial plateau lies between the articular surfaces of the medial and lateral condyles (Fig. 6.55). It is narrow centrally where it is raised to form the intercondylar eminence, the sides of which are elevated further to form medial and lateral intercondylar tubercles.


Anatomy_Gray

Anatomy_Gray. The intercondylar region bears six distinct facets for the attachment of menisci and cruciate ligaments. The anterior intercondylar area widens anteriorly and bears three facets: The most anterior facet is for attachment of the anterior end (horn) of the medial meniscus. Immediately posterior to the most anterior facet is a facet for the attachment of the anterior cruciate ligament. A small facet for the attachment of the anterior end (horn) of the lateral meniscus is just lateral to the site of attachment of the anterior cruciate ligament. The posterior intercondylar area also bears three attachment facets: The most anterior is for attachment of the posterior horn of the lateral meniscus. Posteromedial to the most anterior facet is the site of attachment for the posterior horn of the medial meniscus. Behind the site of attachment for the posterior horn of the medial meniscus is a large facet for the attachment of the posterior cruciate ligament.


Anatomy_Gray

Anatomy_Gray. Behind the site of attachment for the posterior horn of the medial meniscus is a large facet for the attachment of the posterior cruciate ligament. In addition to these six sites of attachment for menisci and cruciate ligaments, a large anterolateral region of the anterior intercondylar area is roughened and perforated by numerous small nutrient foramina for blood vessels. This region is continuous with a similar surface on the front of the tibia above the tuberosity and lies against infrapatellar connective tissue. The tibial tuberosity is a palpable inverted triangular area on the anterior aspect of the tibia below the site of junction between the two condyles (Fig. 6.55). It is the site of attachment for the patellar ligament, which is a continuation of the quadriceps femoris tendon below the patella. Shaft of tibia


Anatomy_Gray

Anatomy_Gray. Shaft of tibia The shaft of the tibia is triangular in cross section and has three surfaces (posterior, medial, and lateral) and three borders (anterior, interosseous, and medial) (Fig. 6.55D): The anterior border is sharp and descends from the tibial tuberosity where it is continuous superiorly with a ridge that passes along the lateral margin of the tuberosity and onto the lateral condyle. The interosseous border is a subtle vertical ridge that descends along the lateral aspect of the tibia from the region of bone anterior and inferior to the articular facet for the head of the fibula. The medial border is indistinct superiorly where it begins at the anterior end of the groove on the posterior surface of the medial tibial condyle, but is sharp in midshaft.


Anatomy_Gray

Anatomy_Gray. The medial border is indistinct superiorly where it begins at the anterior end of the groove on the posterior surface of the medial tibial condyle, but is sharp in midshaft. The large medial surface of the shaft of the tibia, between the anterior and medial borders, is smooth and subcutaneous, and is palpable along almost its entire extent. Medial and somewhat inferior to the tibial tuberosity, this medial surface bears a subtle, slightly roughened elongate elevation. This elevation is the site of the combined attachment of three muscles (sartorius, gracilis, and semitendinosus), which descend from the thigh. The posterior surface of the shaft of the tibia, between the interosseous and medial borders, is widest superiorly where it is crossed by a roughened oblique line (the soleal line). The lateral surface, between the anterior and interosseous borders, is smooth and unremarkable. Proximal end of fibula


Anatomy_Gray

Anatomy_Gray. The lateral surface, between the anterior and interosseous borders, is smooth and unremarkable. Proximal end of fibula The fibula is the lateral bone of the leg and does not take part in formation of the knee joint or in weight-bearing. It is much smaller than the tibia and has a small proximal head, a narrow neck, and a delicate shaft, which ends as the lateral malleolus at the ankle. The head of the fibula is a globe-shaped expansion at the proximal end of the fibula (Fig. 6.56). A circular facet on the superomedial surface is for articulation above with a similar facet on the inferior aspect of the lateral condyle of the tibia. Just posterolateral to this facet, the bone projects superiorly as a blunt apex (styloid process). The lateral surface of the head of the fibula bears a large impression for the attachment of the biceps femoris muscle. A depression near the upper margin of this impression is for attachment of the fibular collateral ligament of the knee joint.


Anatomy_Gray

Anatomy_Gray. The neck of the fibula separates the expanded head from the shaft. The common fibular nerve lies against the posterolateral aspect of the neck. Like the tibia, the shaft of the fibula has three borders (anterior, posterior, and interosseous) and three surfaces (lateral, posterior, and medial), which lie between the borders (Fig. 6.56): The anterior border is sharp midshaft and begins superiorly from the anterior aspect of the head. The posterior border is rounded and descends from the region of the styloid process of the head. The interosseous border is medial in position. The three surfaces of the fibula are associated with the three muscular compartments (lateral, posterior, and anterior) of the leg. Muscles of the thigh are arranged in three compartments separated by intermuscular septa (Fig. 6.57).


Anatomy_Gray

Anatomy_Gray. Muscles of the thigh are arranged in three compartments separated by intermuscular septa (Fig. 6.57). The anterior compartment of the thigh contains the sartorius and the four large quadriceps femoris muscles (rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius). All are innervated by the femoral nerve. In addition, the terminal ends of the psoas major and iliacus muscles pass into the upper part of the anterior compartment from sites of origin on the posterior abdominal wall. These muscles are innervated by branches directly from the anterior rami of L1 to L3 (psoas major) or from the femoral nerve (iliacus) as it passes down the abdominal wall.


Anatomy_Gray

Anatomy_Gray. The medial compartment of the thigh contains six muscles (gracilis, pectineus, adductor longus, adductor brevis, adductor magnus, and obturator externus). All except the pectineus, which is innervated by the femoral nerve, and part of the adductor magnus, which is innervated by the sciatic nerve, are innervated by the obturator nerve. The posterior compartment of the thigh contains three large muscles termed the “hamstrings.” All are innervated by the sciatic nerve. Muscles in the anterior compartment (Table 6.3) act on the hip and knee joints: the psoas major and iliacus act on the hip joint, the sartorius and rectus femoris act on both the hip and knee joints, and the vastus muscles act on the knee joint. The psoas major and iliacus muscles originate on the posterior abdominal wall and descend into the upper part of the anterior compartment of the thigh through the lateral half of the gap between the inguinal ligament and the pelvic bone (Fig. 6.58).


Anatomy_Gray

Anatomy_Gray. Although the iliacus and psoas major originate as separate muscles in the abdomen, both insert by a common tendon onto the lesser trochanter of the femur and together are usually referred to as the iliopsoas muscle. The iliopsoas is a powerful flexor of the thigh at the hip joint and can also contribute to lateral rotation of the thigh. The psoas major is innervated by branches from the anterior rami of L1 to L3 and the iliacus is innervated by branches from the femoral nerve in the abdomen. Quadriceps femoris—vastus medialis, intermedius, and lateralis and rectus femoris The large quadriceps femoris muscle consists of three vastus muscles (vastus medialis, vastus intermedius, and vastus lateralis) and the rectus femoris muscle (Fig. 6.59).


Anatomy_Gray

Anatomy_Gray. The large quadriceps femoris muscle consists of three vastus muscles (vastus medialis, vastus intermedius, and vastus lateralis) and the rectus femoris muscle (Fig. 6.59). The quadriceps femoris muscle mainly extends the leg at the knee joint, but the rectus femoris component also assists flexion of the thigh at the hip joint. Because the vastus muscles insert into the margins of the patella as well as into the quadriceps femoris tendon, they stabilize the position of the patella during knee joint movement. The quadriceps femoris is innervated by the femoral nerve with contributions mainly from spinal segments L3 and L4. A tap with a tendon hammer on the patellar ligament therefore tests reflex activity mainly at spinal cord levels L3 and L4. The vastus muscles originate from the femur, whereas the rectus femoris muscle originates from the pelvic bone. All attach first to the patella by the quadriceps femoris tendon and then to the tibia by the patellar ligament.


Anatomy_Gray

Anatomy_Gray. The vastus medialis originates from a continuous line of attachment on the femur, which begins anteromedially on the intertrochanteric line and continues posteroinferiorly along the pectineal line and then descends along the medial lip of the linea aspera and onto the medial supracondylar line. The fibers converge onto the medial aspect of the quadriceps femoris tendon and the medial border of the patella (Fig. 6.59). The vastus intermedius originates mainly from the upper two-thirds of the anterior and lateral surfaces of the femur and the adjacent intermuscular septum (Fig. 6.59). It merges into the deep aspect of the quadriceps femoris tendon and also attaches to the lateral margin of the patella and lateral condyle of the tibia.


Anatomy_Gray

Anatomy_Gray. A tiny muscle (articularis genus) originates from the femur just inferior to the origin of the vastus intermedius and inserts into the suprapatellar bursa associated with the knee joint (Fig. 6.59). This articular muscle, which is often part of the vastus intermedius muscle, pulls the bursa away from the knee joint during extension. The vastus lateralis is the largest of the vastus muscles (Fig. 6.59). It originates from a continuous line of attachment, which begins anterolaterally from the superior part of the intertrochanteric line of the femur and then circles laterally around the bone to attach to the lateral margin of the gluteal tuberosity and continues down the upper part of the lateral lip of the linea aspera. Muscle fibers converge mainly onto the quadriceps femoris tendon and the lateral margin of the patella. Unlike the vastus muscles, which cross only the knee joint, the rectus femoris muscle crosses both the hip and the knee joints (Fig. 6.59).


Anatomy_Gray

Anatomy_Gray. Unlike the vastus muscles, which cross only the knee joint, the rectus femoris muscle crosses both the hip and the knee joints (Fig. 6.59). The rectus femoris has two tendinous heads of origin from the pelvic bone: one from the anterior inferior iliac spine (straight head), and the other from a roughened area of the ilium immediately superior to the acetabulum (reflected head) (Fig. 6.59). The two heads of the rectus femoris unite to form an elongate muscle belly, which lies anterior to the vastus intermedius muscle and between the vastus lateralis and vastus medialis muscles, to which it is attached on either side. At the distal end, the rectus femoris muscle converges on the quadriceps femoris tendon and inserts on the base of the patella.


Anatomy_Gray

Anatomy_Gray. The patellar ligament is functionally the continuation of the quadriceps femoris tendon below the patella and is attached above to the apex and margins of the patella and below to the tibial tuberosity (Fig. 6.59). The more superficial fibers of the quadriceps femoris tendon and the patellar ligament are continuous over the anterior surface of the patella, and lateral and medial fibers are continuous with the ligament beside the margins of the patella. The sartorius muscle is the most superficial muscle in the anterior compartment of the thigh and is a long strap-like muscle that descends obliquely through the thigh from the anterior superior iliac spine to the medial surface of the proximal shaft of the tibia (Fig. 6.59). Its flat aponeurotic insertion into the tibia is immediately anterior to the insertion of the gracilis and semitendinosus muscles.


Anatomy_Gray

Anatomy_Gray. The sartorius, gracilis, and semitendinosus muscles attach to the tibia in a three-pronged pattern on the tibia, so their combined tendons of insertion are often termed the pes anserinus (Latin for “goose foot”). In the upper one-third of the thigh, the medial margin of the sartorius forms the lateral margin of the femoral triangle. In the middle one-third of the thigh, the sartorius forms the anterior wall of the adductor canal. The sartorius muscle assists in flexing the thigh at the hip joint and the leg at the knee joint. It also abducts the thigh and rotates it laterally, as when resting the foot on the opposite knee when sitting. The sartorius is innervated by the femoral nerve.


Anatomy_Gray

Anatomy_Gray. The sartorius is innervated by the femoral nerve. There are six muscles in the medial compartment of the thigh (Table 6.4): gracilis, pectineus, adductor longus, adductor brevis, adductor magnus, and obturator externus (Fig. 6.60). Collectively, all these muscles except the obturator externus mainly adduct the thigh at the hip joint; the adductor muscles may also medially rotate the thigh. Obturator externus is a lateral rotator of the thigh at the hip joint. The gracilis is the most superficial of the muscles in the medial compartment of thigh and descends almost vertically down the medial side of the thigh (Fig. 6.60). It is attached above to the outer surface of the ischiopubic ramus of the pelvic bone and below to the medial surface of the proximal shaft of the tibia, where it lies sandwiched between the tendon of sartorius in front and the tendon of the semitendinosus behind.


Anatomy_Gray

Anatomy_Gray. The pectineus is a flat quadrangular muscle (Fig. 6.61). It is attached above to the pectineal line of the pelvic bone and adjacent bone, and descends laterally to attach to an oblique line extending from the base of the lesser trochanter to the linea aspera on the posterior surface of the proximal femur. From its origin on the pelvic bone, the pectineus passes into the thigh below the inguinal ligament and forms part of the floor of the medial half of the femoral triangle. The pectineus adducts and flexes the thigh at the hip joint and is innervated by the femoral nerve. The adductor longus is a flat fan-shaped muscle that originates from a small rough triangular area on the external surface of the body of the pubis just inferior to the pubic crest and lateral to the pubic symphysis (Fig. 6.61). It expands as it descends posterolaterally to insert via an aponeurosis into the middle third of the linea aspera.


Anatomy_Gray

Anatomy_Gray. The adductor longus contributes to the floor of the femoral triangle, and its medial margin forms the medial border of the femoral triangle. The muscle also forms the proximal posterior wall of the adductor canal. The adductor longus adducts and medially rotates the thigh at the hip joint and is innervated by the anterior division of the obturator nerve. The adductor brevis lies posterior to the pectineus and adductor longus. It is a triangular muscle attached at its apex to the body of the pubis and inferior pubic ramus just superior to the origin of the gracilis muscle (Fig. 6.61). The muscle is attached by its expanded base via an aponeurosis to a vertical line extending from lateral to the insertion of the pectineus into the upper aspect of the linea aspera lateral to the attachment of the adductor longus. The adductor brevis adducts and medially rotates the thigh at the hip joint and is innervated by the obturator nerve.


Anatomy_Gray

Anatomy_Gray. The adductor brevis adducts and medially rotates the thigh at the hip joint and is innervated by the obturator nerve. The adductor magnus is the largest and deepest of the muscles in the medial compartment of the thigh (Fig. 6.62). The muscle forms the distal posterior wall of the adductor canal. Like the adductor longus and brevis muscles, the adductor magnus is a triangular or fan-shaped muscle anchored by its apex to the pelvis and attached by its expanded base to the femur.


Anatomy_Gray

Anatomy_Gray. On the pelvis, the adductor magnus is attached along a line that extends from the inferior pubic ramus, above the attachments of the adductor longus and brevis muscles, and along the ramus of the ischium to the ischial tuberosity. The part of the muscle that originates from the ischiopubic ramus expands laterally and inferiorly to insert on the femur along a vertical line of attachment that extends from just inferior to the quadrate tubercle and medial to the gluteal tuberosity, along the linea aspera and onto the medial supracondylar line. This lateral part of the muscle is often termed the “adductor part” of the adductor magnus.


Anatomy_Gray

Anatomy_Gray. The medial part of the adductor magnus, often called the “hamstring part,” originates from the ischial tuberosity of the pelvic bone and descends almost vertically along the thigh to insert via a rounded tendon into the adductor tubercle on the medial condyle of the distal head of the femur. It also inserts via an aponeurosis up onto the medial supracondylar line. A large circular gap inferiorly between the hamstring and adductor parts of the muscle is the adductor hiatus (Fig. 6.62), which allows the femoral artery and associated veins to pass between the adductor canal on the anteromedial aspect of the thigh and the popliteal fossa posterior to the knee. The adductor magnus adducts and medially rotates the thigh at the hip joint. The adductor part of the muscle is innervated by the obturator nerve and the hamstring part is innervated by the tibial division of the sciatic nerve.


Anatomy_Gray

Anatomy_Gray. The obturator externus is a flat fan-shaped muscle. Its expansive body is attached to the external aspect of the obturator membrane and adjacent bone (Fig. 6.62). The muscle fibers converge posterolaterally to form a tendon, which passes posterior to the hip joint and neck of the femur to insert on an oval depression on the lateral wall of the trochanteric fossa. The obturator externus externally rotates the thigh at the hip joint and is innervated by the posterior branch of the obturator nerve. There are three long muscles in the posterior compartment of the thigh: biceps femoris, semitendinosus, and semimembranosus (Table 6.5)—and they are collectively known as the hamstrings (Fig. 6.63). All except the short head of the biceps femoris cross both the hip and knee joints. As a group, the hamstrings flex the leg at the knee joint and extend the thigh at the hip joint. They are also rotators at both joints.


Anatomy_Gray

Anatomy_Gray. The biceps femoris muscle is lateral in the posterior compartment of the thigh and has two heads (Fig. 6.63): The long head originates with the semitendinosus muscle from the inferomedial part of the upper area of the ischial tuberosity. The short head arises from the lateral lip of the linea aspera on the shaft of the femur. The muscle belly of the long head crosses the posterior thigh obliquely from medial to lateral and is joined by the short head distally. Together, fibers from the two heads form a tendon, which is palpable on the lateral side of the distal thigh. The main part of the tendon inserts into the lateral surface of the head of the fibula. Extensions from the tendon blend with the fibular collateral ligament and with ligaments associated with the lateral side of the knee joint.


Anatomy_Gray

Anatomy_Gray. The biceps femoris flexes the leg at the knee joint. The long head also extends and laterally rotates the hip. When the knee is partly flexed, the biceps femoris can laterally rotate the leg at the knee joint. The long head is innervated by the tibial division of the sciatic nerve and the short head is innervated by the common fibular division of the sciatic nerve. The semitendinosus muscle is medial to the biceps femoris muscle in the posterior compartment of the thigh (Fig. 6.63). It originates with the long head of the biceps femoris muscle from the inferomedial part of the upper area of the ischial tuberosity. The spindle-shaped muscle belly ends in the lower half of the thigh and forms a long cord-like tendon, which lies on the semimembranosus muscle and descends to the knee. The tendon curves around the medial condyle of the tibia and inserts into the medial surface of the tibia just posterior to the tendons of the gracilis and sartorius muscles as part of the pes anserinus.


Anatomy_Gray

Anatomy_Gray. The semitendinosus flexes the leg at the knee joint and extends the thigh at the hip joint. Working with the semimembranosus, it also medially rotates the thigh at the hip joint and medially rotates the leg at the knee joint. The semitendinosus muscle is innervated by the tibial division of the sciatic nerve. The semimembranosus muscle lies deep to the semitendinosus muscle in the posterior compartment of the thigh (Fig. 6.63). It is attached above to the superolateral impression on the ischial tuberosity and below mainly to the groove and adjacent bone on the medial and posterior surfaces of the medial tibial condyle. Expansions from the tendon also insert into and contribute to the formation of ligaments and fascia around the knee joint. The semimembranosus flexes the leg at the knee joint and extends the thigh at the hip joint. Working with the semitendinosus muscle, it medially rotates the thigh at the hip joint and the leg at the knee joint.


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Anatomy_Gray. The semimembranosus muscle is innervated by the tibial division of the sciatic nerve. Three arteries enter the thigh: the femoral artery, the obturator artery, and the inferior gluteal artery. Of these, the femoral artery is the largest and supplies most of the lower limb. The three arteries contribute to an anastomotic network of vessels around the hip joint. The femoral artery is the continuation of the external iliac artery and begins as the external iliac artery passes under the inguinal ligament to enter the femoral triangle on the anterior aspect of the upper thigh (Fig. 6.65). The femoral artery is palpable in the femoral triangle just inferior to the inguinal ligament midway between the anterior superior iliac spine and the pubic symphysis.


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Anatomy_Gray. The femoral artery passes vertically through the femoral triangle and then continues down the thigh in the adductor canal. It leaves the canal by passing through the adductor hiatus in the adductor magnus muscle and becomes the popliteal artery behind the knee. A cluster of four small branches—superficial epigastric artery, superficial circumflex iliac artery, superficial external pudendal artery, and deep external pudendal artery—originate from the femoral artery in the femoral triangle and supply cutaneous regions of the upper thigh, lower abdomen, and perineum. Deep artery of thigh


Anatomy_Gray

Anatomy_Gray. Deep artery of thigh The largest branch of the femoral artery in the thigh is the deep artery of the thigh (profunda femoris artery), which originates from the lateral side of the femoral artery in the femoral triangle and is the major source of blood supply to the thigh (Fig. 6.65). The deep artery of the thigh immediately passes: posteriorly between the pectineus and adductor longus muscles and then between the adductor longus and adductor brevis muscles, and then travels inferiorly between the adductor longus and adductor magnus, eventually penetrating through the adductor magnus to connect with branches of the popliteal artery behind the knee. The deep artery of the thigh has lateral and medial circumflex femoral branches and three perforating branches.


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Anatomy_Gray. The deep artery of the thigh has lateral and medial circumflex femoral branches and three perforating branches. The lateral circumflex femoral artery normally originates proximally from the lateral side of the deep artery of the thigh, but may arise directly from the femoral artery (Fig. 6.66). It passes deep to the sartorius and rectus femoris and divides into three terminal branches: One vessel (ascending branch) ascends laterally deep to the tensor fasciae latae muscle and connects with a branch of the medial circumflex femoral artery to form a channel, which circles the neck of the femur and supplies the neck and head of the femur. One vessel (descending branch) descends deep to the rectus femoris, penetrates the vastus lateralis muscle, and connects with a branch of the popliteal artery near the knee.


Anatomy_Gray

Anatomy_Gray. One vessel (descending branch) descends deep to the rectus femoris, penetrates the vastus lateralis muscle, and connects with a branch of the popliteal artery near the knee. One vessel (transverse branch) passes laterally to pierce the vastus lateralis and then circles around the proximal shaft of the femur to anastomose with branches from the medial femoral circumflex artery, the inferior gluteal artery, and the first perforating artery to form the cruciate anastomosis around the hip.


Anatomy_Gray

Anatomy_Gray. The medial circumflex femoral artery normally originates proximally from the posteromedial aspect of the deep artery of the thigh, but may originate from the femoral artery (Fig. 6.66). It passes medially around the shaft of the femur, first between the pectineus and iliopsoas and then between the obturator externus and adductor brevis muscles. Near the margin of the adductor brevis the vessel gives off a small branch, which enters the hip joint through the acetabular notch and anastomoses with the acetabular branch of the obturator artery. The main trunk of the medial circumflex femoral artery passes over the superior margin of the adductor magnus and divides into two major branches deep to the quadratus femoris muscle: One branch ascends to the trochanteric fossa and connects with branches of the gluteal and lateral circumflex femoral arteries.


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Anatomy_Gray. One branch ascends to the trochanteric fossa and connects with branches of the gluteal and lateral circumflex femoral arteries. The other branch passes laterally to participate with branches from the lateral circumflex femoral artery, the inferior gluteal artery, and the first perforating artery in forming an anastomotic network of vessels around the hip.


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Anatomy_Gray. The three perforating arteries branch from the deep artery of the thigh (Fig. 6.66) as it descends anterior to the adductor brevis muscle—the first originates above the muscle, the second originates anterior to the muscle, and the third originates below the muscle. All three penetrate through the adductor magnus near its attachment to the linea aspera to enter and supply the posterior compartment of the thigh. Here, the vessels have ascending and descending branches, which interconnect to form a longitudinal channel, which participates above in forming an anastomotic network of vessels around the hip and inferiorly anastomoses with branches of the popliteal artery behind the knee.


Anatomy_Gray

Anatomy_Gray. The obturator artery originates as a branch of the internal iliac artery in the pelvic cavity and enters the medial compartment of the thigh through the obturator canal (Fig. 6.67). As it passes through the canal, it bifurcates into an anterior branch and a posterior branch, which together form a channel that circles the margin of the obturator membrane and lies within the attachment of the obturator externus muscle. Vessels arising from the anterior and posterior branches supply adjacent muscles and anastomose with the inferior gluteal and medial circumflex femoral arteries. In addition, an acetabular vessel originates from the posterior branch, enters the hip joint through the acetabular notch, and contributes to the supply of the head of the femur.


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Anatomy_Gray. Veins in the thigh consist of superficial and deep veins. Deep veins generally follow the arteries and have similar names. Superficial veins are in the superficial fascia, interconnect with deep veins, and do not generally accompany arteries. The largest of the superficial veins in the thigh is the great saphenous vein. The great saphenous vein originates from a venous arch on the dorsal aspect of the foot and ascends along the medial side of the lower limb to the proximal thigh (see p. 560). Here it passes through the saphenous ring in deep fascia covering the anterior thigh to connect with the femoral vein in the femoral triangle (see p. 566). There are three major nerves in the thigh, each associated with one of the three compartments. The femoral nerve is associated with the anterior compartment of the thigh, the obturator nerve is associated with the medial compartment of the thigh, and the sciatic nerve is associated with the posterior compartment of the thigh.


Anatomy_Gray

Anatomy_Gray. The femoral nerve originates from the lumbar plexus (spinal cord segments L2–L4) on the posterior abdominal wall and enters the femoral triangle of the thigh by passing under the inguinal ligament (Fig. 6.68). In the femoral triangle the femoral nerve lies on the lateral side of the femoral artery and is outside the femoral sheath, which surrounds the vessels. Before entering the thigh, the femoral nerve supplies branches to the iliacus and pectineus muscles. Immediately after passing under the inguinal ligament, the femoral nerve divides into anterior and posterior branches, which supply muscles of the anterior compartment of the thigh and skin on the anterior and medial aspects of the thigh and on the medial sides of the leg and foot.


Anatomy_Gray

Anatomy_Gray. Branches of the femoral nerve (Fig. 6.68) include: anterior cutaneous branches, which penetrate deep fascia to supply skin on the front of the thigh and knee; numerous motor nerves, which supply the quadriceps femoris muscles (rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis muscles) and the sartorius muscle; and one long cutaneous nerve, the saphenous nerve, which supplies skin as far distally as the medial side of the foot. The saphenous nerve accompanies the femoral artery through the adductor canal, but does not pass through the adductor hiatus with the femoral artery. Rather, the saphenous nerve penetrates directly through connective tissues near the end of the canal to appear between the sartorius and gracilis muscles on the medial side of the knee. Here the saphenous nerve penetrates deep fascia and continues down the medial side of the leg to the foot, and supplies skin on the medial side of the knee, leg, and foot.


Anatomy_Gray

Anatomy_Gray. The obturator nerve is a branch of the lumbar plexus (spinal cord segments L2–L4) on the posterior abdominal wall. It descends in the psoas muscle, and then passes out of the medial margin of the psoas muscle to enter the pelvis (Fig. 6.69). The obturator nerve continues along the lateral pelvic wall and then enters the medial compartment of the thigh by passing through the obturator canal. It supplies most of the adductor muscles and skin on the medial aspect of the thigh. As the obturator nerve enters the thigh, it divides into two branches, an anterior branch and a posterior branch, which are separated by the adductor brevis muscle: The posterior branch descends behind the adductor brevis muscle and on the anterior surface of the adductor magnus muscle, and supplies the obturator externus and adductor brevis muscles and the part of the adductor magnus that attaches to the linea aspera.


Anatomy_Gray

Anatomy_Gray. The anterior branch descends on the anterior surface of the adductor brevis muscle and is behind the pectineus and adductor longus muscles—it supplies branches to the adductor longus, gracilis, and adductor brevis muscles, and often contributes to the supply of the pectineus muscle, and cutaneous branches innervate the skin on the medial side of the thigh. The sciatic nerve is a branch of the lumbosacral plexus (spinal cord segments L4–S3) and descends into the posterior compartment of the thigh from the gluteal region (Fig. 6.70). It innervates all muscles in the posterior compartment of the thigh and then its branches continue into the leg and foot. In the posterior compartment of the thigh, the sciatic nerve lies on the adductor magnus muscle and is crossed by the long head of the biceps femoris muscle.


Anatomy_Gray

Anatomy_Gray. In the posterior compartment of the thigh, the sciatic nerve lies on the adductor magnus muscle and is crossed by the long head of the biceps femoris muscle. Proximal to the knee, and sometimes within the pelvis, the sciatic nerve divides into its two terminal branches: the tibial nerve and the common fibular nerve. These nerves travel vertically down the thigh and enter the popliteal fossa posterior to the knee. Here, they meet the popliteal artery and vein. The tibial part of the sciatic nerve, either before or after its separation from the common fibular nerve, supplies branches to all muscles in the posterior compartment of the thigh (long head of biceps femoris, semimembranosus, semitendinosus) except the short head of the biceps femoris, which is innervated by the common fibular part (Fig. 6.70). The tibial nerve descends through the popliteal fossa, enters the posterior compartment of the leg, and continues into the sole of the foot.


Anatomy_Gray

Anatomy_Gray. The tibial nerve descends through the popliteal fossa, enters the posterior compartment of the leg, and continues into the sole of the foot. The tibial nerve innervates: all muscles in the posterior compartment of the leg, all intrinsic muscles in the sole of the foot including the first two dorsal interossei muscles, which also may receive innervation from the deep fibular nerve, and skin on the posterolateral side of the lower half of the leg and lateral side of the ankle, foot, and little toe, and skin on the sole of the foot and toes. The common fibular part of the sciatic nerve innervates the short head of the biceps femoris in the posterior compartment of the thigh and then continues into the lateral and anterior compartments of the leg and onto the foot (Fig. 6.70).


Anatomy_Gray

Anatomy_Gray. The common fibular nerve innervates: all muscles in the anterior and lateral compartments of the leg, one muscle (extensor digitorum brevis) on the dorsal aspect of the foot, the first two dorsal interossei muscles in the sole of the foot, and skin over the lateral aspect of the leg, and ankle, and over the dorsal aspect of the foot and toes. The knee joint is the largest synovial joint in the body. It consists of: the articulation between the femur and tibia, which is weight-bearing, and the articulation between the patella and the femur, which allows the pull of the quadriceps femoris muscle to be directed anteriorly over the knee to the tibia without tendon wear (Fig. 6.71). Two fibrocartilaginous menisci, one on each side, between the femoral condyles and tibia accommodate changes in the shape of the articular surfaces during joint movements.


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Anatomy_Gray. Two fibrocartilaginous menisci, one on each side, between the femoral condyles and tibia accommodate changes in the shape of the articular surfaces during joint movements. The detailed movements of the knee joint are complex, but basically the joint is a hinge joint that allows mainly flexion and extension. Like all hinge joints, the knee joint is reinforced by collateral ligaments, one on each side of the joint. In addition, two very strong ligaments (the cruciate ligaments) interconnect the adjacent ends of the femur and tibia and maintain their opposed positions during movement. Because the knee joint is involved in weight-bearing, it has an efficient “locking” mechanism to reduce the amount of muscle energy required to keep the joint extended when standing.


Anatomy_Gray

Anatomy_Gray. Because the knee joint is involved in weight-bearing, it has an efficient “locking” mechanism to reduce the amount of muscle energy required to keep the joint extended when standing. The articular surfaces of the bones that contribute to the knee joint are covered by hyaline cartilage. The major surfaces involved include: the two femoral condyles, and the adjacent surfaces of the superior aspect of the tibial condyles. The surfaces of the femoral condyles that articulate with the tibia in flexion of the knee are curved or round, whereas the surfaces that articulate in full extension are flat (Fig. 6.72). The articular surfaces between the femur and patella are the V-shaped trench on the anterior surface of the distal end of the femur where the two condyles join and the adjacent surfaces on the posterior aspect of the patella. The joint surfaces are all enclosed within a single articular cavity, as are the intraarticular menisci between the femoral and tibial condyles.


Anatomy_Gray

Anatomy_Gray. There are two menisci, which are fibrocartilaginous C-shaped cartilages, in the knee joint, one medial (medial meniscus) and the other lateral (lateral meniscus) (Fig. 6.73). Both are attached at each end to facets in the intercondylar region of the tibial plateau. The medial meniscus is attached around its margin to the capsule of the joint and to the tibial collateral ligament, whereas the lateral meniscus is unattached to the capsule. Therefore, the lateral meniscus is more mobile than the medial meniscus. The menisci are interconnected anteriorly by a transverse ligament of the knee. The lateral meniscus is also connected to the tendon of the popliteus muscle, which passes superolaterally between this meniscus and the capsule to insert on the femur.


Anatomy_Gray

Anatomy_Gray. The menisci improve congruency between the femoral and tibial condyles during joint movements where the surfaces of the femoral condyles articulating with the tibial plateau change from small curved surfaces in flexion to large flat surfaces in extension. The synovial membrane of the knee joint attaches to the margins of the articular surfaces and to the superior and inferior outer margins of the menisci (Fig. 6.75A). The two cruciate ligaments, which attach in the intercondylar region of the tibia below and the intercondylar fossa of the femur above, are outside the articular cavity, but enclosed within the fibrous membrane of the knee joint. Posteriorly, the synovial membrane reflects off the fibrous membrane of the joint capsule on either side of the posterior cruciate ligament and loops forward around both ligaments thereby excluding them from the articular cavity.


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Anatomy_Gray. Anteriorly, the synovial membrane is separated from the patellar ligament by an infrapatellar fat pad. On each side of the pad, the synovial membrane forms a fringed margin (an alar fold), which projects into the articular cavity. In addition, the synovial membrane covering the lower part of the infrapatellar fat pad is raised into a sharp midline fold directed posteriorly (the infrapatellar synovial fold), which attaches to the margin of the intercondylar fossa of the femur. The synovial membrane of the knee joint forms pouches in two locations to provide low-friction surfaces for the movement of tendons associated with the joint: The smallest of these expansions is the subpopliteal recess (Fig. 6.75A), which extends posterolaterally from the articular cavity and lies between the lateral meniscus and the tendon of the popliteus muscle, which passes through the joint capsule.


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Anatomy_Gray. The second expansion is the suprapatellar bursa (Fig. 6.75B), a large bursa that is a continuation of the articular cavity superiorly between the distal end of the shaft of the femur and the quadriceps femoris muscle and tendon—the apex of this bursa is attached to the small articularis genus muscle, which pulls the bursa away from the joint during extension of the knee. Other bursae associated with the knee but not normally communicating with the articular cavity include the subcutaneous prepatellar bursa, deep and subcutaneous infrapatellar bursae, and numerous other bursae associated with tendons and ligaments around the joint (Fig. 6.75B). The prepatellar bursa is subcutaneous and anterior to the patella. The deep and subcutaneous infrapatellar bursae are on the deep and subcutaneous sides of the patellar ligament, respectively.


Anatomy_Gray

Anatomy_Gray. The prepatellar bursa is subcutaneous and anterior to the patella. The deep and subcutaneous infrapatellar bursae are on the deep and subcutaneous sides of the patellar ligament, respectively. The fibrous membrane of the knee joint is extensive and is partly formed and reinforced by extensions from tendons of the surrounding muscles (Fig. 6.76). In general, the fibrous membrane encloses the articular cavity and the intercondylar region: On the medial side of the knee joint, the fibrous membrane blends with the tibial collateral ligament and is attached on its internal surface to the medial meniscus. Laterally, the external surface of the fibrous membrane is separated by a space from the fibular collateral ligament and the internal surface of the fibrous membrane is not attached to the lateral meniscus.


Anatomy_Gray

Anatomy_Gray. Anteriorly, the fibrous membrane is attached to the margins of the patella where it is reinforced with tendinous expansions from the vastus lateralis and vastus medialis muscles, which also merge above with the quadriceps femoris tendon and below with the patellar ligament. The fibrous membrane is reinforced anterolaterally by a fibrous extension from the iliotibial tract and posteromedially by an extension from the tendon of the semimembranosus (the oblique popliteal ligament), which reflects superiorly across the back of the fibrous membrane from medial to lateral. The upper end of the popliteus muscle passes through an aperture in the posterolateral aspect of the fibrous membrane of the knee and is enclosed by the fibrous membrane as its tendon travels around the joint to insert on the lateral aspect of the lateral femoral condyle.


Anatomy_Gray

Anatomy_Gray. The major ligaments associated with the knee joint are the patellar ligament, the tibial (medial) and fibular (lateral) collateral ligaments, and the anterior and posterior cruciate ligaments. The patellar ligament is basically the continuation of the quadriceps femoris tendon inferior to the patella (Fig. 6.76). It is attached above to the margins and apex of the patella and below to the tibial tuberosity. The collateral ligaments, one on each side of the joint, stabilize the hinge-like motion of the knee (Fig. 6.77). The cord-like fibular collateral ligament is attached superiorly to the lateral femoral epicondyle just above the groove for the popliteus tendon. Inferiorly, it is attached to a depression on the lateral surface of the fibular head. It is separated from the fibrous membrane by a bursa.


Anatomy_Gray

Anatomy_Gray. The broad and flat tibial collateral ligament is attached by much of its deep surface to the underlying fibrous membrane. It is anchored superiorly to the medial femoral epicondyle just inferior to the adductor tubercle and descends anteriorly to attach to the medial margin and medial surface of the tibia above and behind the attachment of the sartorius, gracilis, and semitendinosus tendons. The two cruciate ligaments are in the intercondylar region of the knee and interconnect the femur and tibia (Figs. 6.77D and 6.78). They are termed “cruciate” (Latin for “shaped like a cross”) because they cross each other in the sagittal plane between their femoral and tibial attachments: The anterior cruciate ligament attaches to a facet on the anterior part of the intercondylar area of the tibia and ascends posteriorly to attach to a facet at the back of the lateral wall of the intercondylar fossa of the femur.


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Anatomy_Gray. The posterior cruciate ligament attaches to the posterior aspect of the intercondylar area of the tibia and ascends anteriorly to attach to the medial wall of the intercondylar fossa of the femur. The anterior cruciate ligament crosses lateral to the posterior cruciate ligament as they pass through the intercondylar region. The anterior cruciate ligament prevents anterior displacement of the tibia relative to the femur and the posterior cruciate ligament restricts posterior displacement (Fig. 6.78). When standing, the knee joint is locked into position, thereby reducing the amount of muscle work needed to maintain the standing position (Fig. 6.79). One component of the locking mechanism is a change in the shape and size of the femoral surfaces that articulate with the tibia: In flexion, the surfaces are the curved and rounded areas on the posterior aspects of the femoral condyles.


Anatomy_Gray

Anatomy_Gray. In flexion, the surfaces are the curved and rounded areas on the posterior aspects of the femoral condyles. As the knee is extended, the surfaces move to the broad and flat areas on the inferior aspects of the femoral condyles. Consequently the joint surfaces become larger and more stable in extension. Another component of the locking mechanism is medial rotation of the femur on the tibia during extension. Medial rotation and full extension tightens all the associated ligaments. Another feature that keeps the knee extended when standing is that the body’s center of gravity is positioned along a vertical line that passes anterior to the knee joint. The popliteus muscle unlocks the knee by initiating lateral rotation of the femur on the tibia.


Anatomy_Gray

Anatomy_Gray. The popliteus muscle unlocks the knee by initiating lateral rotation of the femur on the tibia. Vascular supply to the knee joint is predominantly through descending and genicular branches from the femoral, popliteal, and lateral circumflex femoral arteries in the thigh and the circumflex fibular artery and recurrent branches from the anterior tibial artery in the leg. These vessels form an anastomotic network around the joint (Fig. 6.80). The knee joint is innervated by branches from the obturator, femoral, tibial, and common fibular nerves. The small proximal tibiofibular joint is synovial in type and allows very little movement (Fig. 6.82). The opposing joint surfaces, on the undersurface of the lateral condyle of the tibia and on the superomedial surface of the head of the fibula, are flat and circular. The capsule is reinforced by anterior and posterior ligaments.


Anatomy_Gray

Anatomy_Gray. The popliteal fossa is an important area of transition between the thigh and leg and is the major route by which structures pass from one region to the other. The popliteal fossa is a diamond-shaped space behind the knee joint formed between muscles in the posterior compartments of the thigh and leg (Fig. 6.83A): The margins of the upper part of the diamond are formed medially by the distal ends of the semitendinosus and semimembranosus muscles and laterally by the distal end of the biceps femoris muscle. The margins of the smaller lower part of the space are formed medially by the medial head of the gastrocnemius muscle and laterally by the plantaris muscle and the lateral head of the gastrocnemius muscle. The floor of the fossa is formed by the capsule of the knee joint and adjacent surfaces of the femur and tibia, and, more inferiorly, by the popliteus muscle.


Anatomy_Gray

Anatomy_Gray. The floor of the fossa is formed by the capsule of the knee joint and adjacent surfaces of the femur and tibia, and, more inferiorly, by the popliteus muscle. The roof is formed by deep fascia, which is continuous above with the fascia lata of the thigh and below with deep fascia of the leg. The major contents of the popliteal fossa are the popliteal artery, the popliteal vein, and the tibial and common fibular nerves (Fig. 6.83B). The tibial and common fibular nerves originate proximal to the popliteal fossa as the two major branches of the sciatic nerve. They are the most superficial of the neurovascular structures in the popliteal fossa and enter the region directly from above under the margin of the biceps femoris muscle: The tibial nerve descends vertically through the popliteal fossa and exits deep to the margin of the plantaris muscle to enter the posterior compartment of the leg.


Anatomy_Gray

Anatomy_Gray. The tibial nerve descends vertically through the popliteal fossa and exits deep to the margin of the plantaris muscle to enter the posterior compartment of the leg. The common fibular nerve exits by following the biceps femoris tendon over the lower lateral margin of the popliteal fossa, and continues to the lateral side of the leg where it swings around the neck of the fibula and enters the lateral compartment of the leg. The popliteal artery is the continuation of the femoral artery in the anterior compartment of the thigh, and begins as the femoral artery passes posteriorly through the adductor hiatus in the adductor magnus muscle. The popliteal artery appears in the popliteal fossa on the upper medial side under the margin of the semimembranosus muscle. It descends obliquely through the fossa with the tibial nerve and enters the posterior compartment of the leg where it ends just lateral to the midline of the leg by dividing into the anterior and posterior tibial arteries.


Anatomy_Gray

Anatomy_Gray. The popliteal artery is the deepest of the neurovascular structures in the popliteal fossa and is therefore difficult to palpate; however, a pulse can usually be detected by deep palpation near the midline. In the popliteal fossa, the popliteal artery gives rise to branches, which supply adjacent muscles, and to a series of geniculate arteries, which contribute to vascular anastomoses around the knee. The popliteal vein is superficial to and travels with the popliteal artery. It exits the popliteal fossa superiorly to become the femoral vein by passing through the adductor hiatus. Roof of popliteal fossa