FASCIAE AND MUSCLES OF HIP AND THIGH
The region of the hip and thigh extends from the iliac crest to the knee. The upper portion is the hip, which is limited generally by the level of the greater trochanter of the femur. The subcutaneous connective tissue contains a considerable amount of fat, especially in the gluteal region. The subcutaneous tissue here is continuous with the similar layer of the lower abdomen, and the membranous layer of the latter region continues beyond the inguinal ligament to become attached to the fascia lata a short distance beyond the ligament. The layer attaches medially to the pubic tubercle and laterally to the iliac crest. It also attaches to the margins of the saphenous opening and fills the opening itself with the cribriform fascia, a subcutaneous connective tissue perforated for the passage of the greater saphenous vein and other blood and lymphatic vessels.
The fascia lata is the uppermost division of a complete stocking-like investment of the soft parts of the limb (see Plate 2-9). Below the knee, this investment is represented by the crural fascia and the plantar and dorsal fasciae of the foot. The fascia lata is strong, thicker where it has tendinous contributions and thinner in the gluteal region. It has a complete bony attachment to the pelvis at the pubic crest and symphysis, the ischiopubic ramus, and the tuberosity of the ischium. From here, an attachment to the sacrotuberal ligament carries it to the dorsum of the coccyx and the sacrum. It continues to the posterior superior iliac spine and along the external lip of the iliac crest to the anterior superior iliac spine, the inguinal ligament, and the pubic tubercle. Here, a deep lamina follows the pecten of the pubis behind the femoral vein.
The gluteal aponeurosis lies between the iliac crest and the superior border of the gluteus maximus muscle, which provides part of the origin of the gluteus medius. A strong, lateral band, the iliotibial tract, arises from the tubercle of the iliac crest and serves as a tendon of the tensor fasciae latae muscle and as part of the tendon of the gluteus maximus muscle. The tract ends at the knee, where it reinforces the capsule of the knee joint and attaches to the condyle of the tibia.
The lateral and medial intermuscular septa unite the fascia lata to the periosteum of the femur and separate the muscles of the posterior and anterior compartments and the muscles of the medial and anterior groups. The medial intermuscular septum splits to enclose the sartorius muscle and helps to form the adductor canal (see Plate 2-8). The iliotibial tract attaches deeply to the lateral intermuscular septum.
The muscles of the hip and thigh are divided into four groups: anterior, medial, posterior, and lateral femoral muscles (see Plates 2-8 to 2-10). Additionally, the psoas major and iliacus muscles, although located for the most part and arising within the lower abdomen, insert into the thigh (lesser trochanter of femur) and have their principal action as flexors of the thigh. In systematizing the femoral muscles, it is useful to note that muscles arising from the pubis and ischium are preaxial and are innervated by nerves derived from the anterior branches of the lumbosacral plexus, namely, the obturator or tibial nerves; however, muscles arising from the ilium or femur are postaxial and are innervated by either the femoral or common peroneal nerves of posterior branch derivation. The anterior group muscles are all postaxial in classification and innervation, and the medial group muscles are preaxial. The posterior and lateral groups contain muscles of both types.
ANTERIOR FEMORAL MUSCLES
The anterior femoral muscles are the sartorius, quadriceps femoris (combined rectus femoris and vastus muscles), and the articularis genus muscles (see Plate 2-8).
The sartorius is the longest muscle in the body. Ribbon-like in form, it arises from the anterior superior spine of the ilium and from the notch just below the spine. It is diagonally placed, ending on the medial side of the leg. Its insertion is into the medial surface of the tibia, below the tuberosity and nearly as far forward as the crest. In this insertion, it is associated with the tendons of the gracilis and semitendinosus muscles in the pes anserinus, which is separated from the tibia by a bursa. Contraction of the sartorius produces flexion, abduction, and lateral rotation of the thigh. It also flexes the leg, for its tendon passes behind the transverse axis of the knee. The sartorius forms the lateral border of the femoral triangle in the upper third of the thigh; in the middle third, it forms the roof of the adductor canal. The femoral nerve innervates the sartorius muscle by two branches, with nerve fibers from L2 and L3.
The four parts of the quadriceps femoris muscle arise separately but end in closely related parts of the tibia the tuberosity and condyles. The rectus femoris muscle, as its name implies, runs straight down the thigh. Some-what fusiform in shape, its superficial fibers have a bipennate arrangement. The muscle arises by two tendons. The straight head takes origin from the anterior inferior spine of the ilium; the reflected head arises from the groove above the acetabulum. These tendons unite at an acute angle and continue into a central aponeurosis that is expanded downward into the muscle. From this, the muscle fibers arise, turn around its margin, and end in the tendon of insertion. The latter broadens to attach to the proximal border of the patella and spreads over its surface to the tuberosity of the tibia (patellar ligament). Two branches of the femoral nerve with fibers from L3 and L4 innervate the muscle.
The vastus lateralis muscle is the largest component of the quadriceps femoris muscle. It arises from the femur by a broad aponeurosis attached to the upper part of the intertrochanteric line, the anterior and inferior borders of the greater trochanter, the gluteal tuberosity, the immediately adjacent portion of the lateral lip of the linea aspera, and the lateral intermuscular septum throughout its length. This aponeurosis covers the superior portion of the muscle, and from its deep surface, many muscle fibers take origin. The tendon of the vastus lateralis muscle inserts into the superolateral border of the patella and the lateral condyle of the tibia. The large branch of the femoral nerve (L3, 4) to the vastus lateralis muscle accompanies the descending branch of the lateral circumflex femoral artery.
The vastus medialis muscle arises from the whole extent of the medial lip of the linea aspera, the distal half of the intertrochanteric line, and the medial inter-muscular septum. The aponeurotic fibers of origin adhere to the tendons of insertion of the adductor longus and adductor magnus muscles. The fibers are directed downward and forward toward the knee. The aponeurotic tendon inserts into the tendon of the rectus femoris, the superomedial border of the patella, and the medial condyle of the tibia. Two branches of the femoral nerve (L3, 4) supply this muscle.
The vastus intermedius muscle arises from the shaft of the femur, from the lower half of the lateral lip of the linea aspera, and from the lateral intermuscular septum.
Its fibers end in a superficial aponeurosis, which blends with the deep surface of the tendons of the rectus femoris and with the vastus medialis and vastus lateralis muscles. The vastus intermedius is innervated superficially by a branch of the femoral nerve (L3, 4) and also by the upper nerve to the vastus medialis.
The four parts of the quadriceps femoris muscle con- verge on the patella, which is regarded as a sesamoid developed in its tendon. The patellar ligament is the terminal part of the tendinous insertion of the quadriceps femoris muscle. It ends in the tuberosity of the tibia. The suprapatellar bursa intervenes between the quadriceps femoris tendon and the lower end of the femur and communicates freely with the cavity of the knee joint. A deep infrapatellar bursa lies between the patellar ligament (just above its insertion) and the tibia. Medial and lateral patellar retinacula insert into the condyles of the tibia.
The quadriceps femoris muscle is the great extensor of the leg at the knee, with all parts of the muscle contributing to this action. The line of traction, which is along the axis of the femur, is not directly in line with the tibia. Thus, there is a tendency to displace the patella lateralward as the muscle contracts. The numerous low, almost horizontal fibers of the vastus medialis muscle counter this displacing force. The rectus femoris muscle also acts in flexion of the thigh at the hip. Its two, almost right-angled tendons of origin combine to serve the full range of flexion action. Initially in line with the rest of the muscle, the straight tendon becomes less effective as the thigh is flexed, but as this tendon loses its effectiveness, the flexed thigh becomes more and more in line with the reflected tendon, and thus its attachment becomes the optimal site for traction. The quadriceps muscles are generally uncontracted in relaxed standing.
The articularis genus muscle consists of a number of small muscular bundles that arise from the lower fourth of the front of the femur. Lying deep to the vastus intermedius muscle, these bundles insert into the upper part of the synovial membrane of the knee joint.
MEDIAL FEMORAL MUSCLES
The medial femoral muscles are the gracilis, pectineus, adductor longus, adductor brevis, adductor magnus, and obturator externus muscles (see Plate 2-8).
The gracilis muscle is long and slender and is superficially placed on the medial aspect of the thigh. Its thin tendon arises along the pubic symphysis and the inferior ramus of the pubis. Its tapered tendon inserts into the upper part of the shaft of the tibia as part of the pes anserinus, lying between the tendons of the sartorius and semitendinosus muscles. A bursa deep to the tendon separates it from the tibial collateral ligament. The gracilis muscle adducts the thigh and assists in flexion of the leg at the knee. It also participates in flexion and medial rotation of the thigh at the hip. The gracilis muscle is innervated by a branch of the anterior division of the obturator nerve (L2, 3).
The pectineus muscle is flat and quadrangular and forms the medial part of the floor of the femoral tri- angle. It arises from the pecten of the pubis and the surface of the bone below the pecten, between the ilio- pubic eminence laterally and the pubic tubercle medially. The fibers of the muscle pass downward, backward, and lateralward and insert by a 5-cm-wide tendon into the pectineal line of the femur. The muscle adducts, rotates medially, and assists in flexion of the thigh. It is supplied by a branch of the femoral nerve, which enters the lateral portion of the muscle, and also by the accessory obturator nerve, when this is present. There are variable divisions of the muscle into ventromedial and dorsolateral portions.
The adductor longus muscle lies in the same plane as the pectineus and forms the medial boundary of the femoral triangle. It arises in a flat, narrow tendon from the medial portion of the superior ramus of the pubis. It expands into a broad, triangular muscular belly and inserts by a thin tendon into the middle third of the medial lip of the linea aspera of the femur, between the tendons of the vastus medialis and the adductor magnus muscles. The adductor longus muscle adducts the thigh and assists in its flexion and medial rotation. Its nerve, a branch of the anterior division of the obturator nerve (L2, 3), reaches it on the deep surface of its middle third.
The adductor brevis muscle is deep to the pectineus and adductor longus muscles. It is an adductor of the thigh and, to a lesser degree, assists in its flexion and medial rotation. The adductor brevis has a narrow origin from the inferior pubic ramus, between the origins of the gracilis and obturator externus muscles. Its muscular fibers fan out to end in an aponeurosis that inserts into the lower two thirds of the pectineal line of the femur and the upper half of the medial lip of the linea aspera. Branches of the anterior division of the obturator nerve (L2, 3) enter the middle third of the muscle near its proximal border. Its tendon is pierced by perforating branches of the deep femoral artery and their accompanying veins.
The adductor magnus muscle is the largest muscle of the medial femoral group. It is triangular and actually consists of a combination of two muscles that have different innervations. The muscle arises from the lower part of the inferior pubic ramus, the ramus of the ischium, and the ischial tuberosity. Its muscular fibers fan out to the whole length of the linea aspera of the femur; the upper fibers are horizontal and the lower fibers are vertical. The upper horizontal fibers, some-times designated as the adductor minimus muscle, insert into the medial side of the gluteal ridge and the uppermost part of the linea aspera of the femur. Below this, the aponeurosis of insertion ends in the whole length of the medial lip of the linea aspera and the supracondylar line of the femur.
The most medial and posterior portion of the muscle, its ischiocondylar portion, arises from the ischial tuberosity and forms a round tendon that ends in the adductor tubercle of the medial epicondyle of the femur. The upper anterior portion of the muscle is a strong adductor and assists in flexion and medial rotation of the thigh. It is innervated by the posterior division of the obturator nerve (L3, 4). The ischiocondylar portion of the muscle is one of the hamstring muscles of the back of the thigh. Its particular action is to extend the thigh and rotate it; it is innervated on its dorsal surface by a branch from the tibial division of the sciatic nerve (L4; S1).
In the lower third of the thigh, aponeurotic fibers spread lateralward from the rounded tendon of the adductor magnus muscle toward the vastus medialis muscle and end in the medial intermuscular septum.
This strong vastoadductor membrane covers the distal end of the adductor canal and may be pierced for the passage of the saphenous nerve and the descending genicular artery and vein. Farther, the aponeurosis of insertion of the adductor magnus muscle is pierced adjacent to the femur by four openings for the passage of the perforating branches of the deep femoral artery and accompanying veins, Finally, a large gap exists between the lower end of the aponeurosis and the tendon to the adductor tubercle. Through this adductor hiatus, the femoral vessels pass back and down into the popliteal space, where they become the popliteal vessels. The obturator externus muscle arises from the external aspect of the superior and inferior rami of the pubis and the ramus of the ischium and from the external surface of the obturator membrane. Its tendon passes across the back of the neck of the femur and the capsule of the hip joint to insert in the trochanteric fossa of the femur.
The synovial membrane of the hip joint acts as a bursa separating the tendon from the neck of the femur. This muscle is a lateral rotator of the thigh. It is supplied by a branch of the obturator nerve (L3, 4).
POSTERIOR FEMORAL MUSCLES
The posterior femoral muscles compose the hamstring group, which includes the semitendinosus, semimembranosus, and biceps femoris muscles, and the ischiocondylar portion of the adductor magnus (see Plate 2-10).
The semitendinosus muscle is aptly named, because about half its length is tendinous. It arises from the lower and medial impression on the tuberosity of the ischium in common with the long head of the biceps femoris muscle. The semitendinosus tendon forms the medial margin of the popliteal space at the knee; it then curves around the medial condyle of the tibia and inserts as part of the pes anserinus into the upper part of the medial surface of the tibia. It is separated from the tibial collateral ligament by a bursa. Two branches of the tibial division of the sciatic nerve (L4, 5; S1, 2) usually reach this muscle.
The semimembranosus muscle arises by a long, flat tendon (or membrane) from the upper and outer impression on the tuberosity of the ischium. The muscular belly begins about halfway down the thigh. The insertion of the muscle at the knee is rather complex. It ends mainly in the horizontal groove on the posteromedial aspect of the medial condyle of the tibia, but a prominent reflection from here forms the oblique popliteal ligament of the knee joint capsule. Other fibers extend from the tendon to the tibial collateral ligament and onto the fascia of the popliteus muscle. The semimembranosus muscle is innervated by a branch of the tibial division of the sciatic nerve arising in common with the lower nerve to the semitendinosus muscle.
The biceps femoris muscle is a secondary combination of one preaxial muscle, the long head, and one postaxial muscle, the short head. The long head arises in combination with the semitendinosus muscle from the lower and medial impression of the ischial tuberosity and the lower part of the sacrotuberal ligament. The short head arises from the lateral lip of the linea aspera of the femur, the proximal two thirds of the supracondylar line, and the lateral intermuscular septum. The muscle fibers of the short head join the tendon of the long head to form the heavy round tendon that forms the lateral margin of the popliteal fossa.
At the knee, the tendon divides around the fibular collateral ligament and ends on the lateral aspect of the head of the fibula, the lateral condyle of the tibia, and in the deep fascia of the lateral aspect of the leg. As a combination of two muscles of differing origins, the two heads are differently innervated. The long head usually receives two branches of the tibial division of the sciatic nerve (S1, 2, 3), one to the upper third and one to the middle third of the muscle. The nerve to the short head is a branch of the common peroneal division of the sciatic nerve (L5; S1, 2), which enters the superficial surface of the muscle.
The hamstring muscles flex the leg and extend the thigh. Their ligamentous, or protective, action at the hip joint is important. In the usual movement, flexion and extension are carried out together, and maximal excursion at one joint carries the limitation of less than maximal excursion at the other. There is also minimal rotary action, the “semi” muscles rotating the flexed leg medially and the biceps femoris muscle rotating it laterally.
LATERAL FEMORAL MUSCLES
The lateral femoral muscles lie largely in the hip region. They are the gluteus maximus, gluteus medius, gluteus minimus, tensor fasciae latae, piriformis, obturator internus, superior gemellus, inferior gemellus, and quadratus femoris muscles (see Plates 2-10 and 2-13).
The gluteus maximus muscle is a heavy, coarsely fasciculated muscle, superficially situated in the buttock. It is quadrilateral, and its fasciculi are directed down- ward and outward. The muscle arises from the posterior gluteal line of the ilium and the area of the bone above and behind it, the posterior surface of the sacrum and coccyx, the sacrotuberal ligament, and the gluteal aponeurosis overlying the gluteus medius muscle. The larger upper portion and the superficial fibers of the lower portion insert into the iliotibial tract of the fascia lata; the deeper fibers of the lower portion reach the gluteal tuberosity of the femur and the lateral intermuscular septum.
The upper portion of the muscle is separated from the greater trochanter of the femur by the large trochanteric bursa. Other bursae separate the tendon of the muscle from the origin of the vastus lateralis muscle (of the quadriceps femoris muscle) and the lower portion of the muscle from the ischial tuberosity. The gluteus maximus is distinctly a muscle of the erect posture but becomes active only under conditions of effort. It is a powerful extensor of the thigh and, acting from its insertion, equally an extensor of the trunk. It is a strong lateral rotator, and its superior fibers come into play in forcible abduction of the thigh. Its insertion into the iliotibial tract may promote stability of the femur on the tibia, but the extensive blending of this tract with the lateral intermuscular septum would prevent significant action of the muscle on the tibia. The inferior gluteal nerve (L5; S1, 2) is the sole supply of this muscle.
The gluteus medius muscle lies largely anterior to the gluteus maximus under the strong vertical fibers of the gluteal aponeurosis but also partly underlies the gluteus maximus. It arises from the external surface of the ilium between the anterior and posterior gluteal lines and from the gluteal aponeurosis. Its flattened tendon inserts into the posterosuperior angle of the greater trochanter of the femur and into a diagonal ridge on its lateral surface. A bursa separates the tendon from the trochanter proximal to its insertion.
The gluteus minimus muscle underlies the gluteus medius, arising from the ilium between its anterior gluteal and inferior gluteal lines. Its insertion is onto the anterosuperior angle of the greater trochanter, with a bursa intervening between the tendon and the medial part of the anterior surface of the trochanter. The gluteus medius and minimus muscles abduct the femur and rotate the thigh medialward. These are important functions in walking, because when one foot is raised off the ground, the gluteus muscles, holding the pelvic bone of the other side down toward the greater trochanter, prevent the collapse of the pelvis on its unsupported side. The same muscles, by their rotary action, swing the pelvis forward as the step is taken. Both muscles are innervated by the superior gluteal nerve (L4, 5; S1), accompanied by branches of the superior gluteal vessels between the two muscles.
The tensor fasciae latae muscle is fusiform and is enclosed between two layers of the fascia lata. It arises from the anterior part of the external lip of the iliac crest, the outer surface of the anterior superior spine of the ilium, and the notch below the spine. The muscle inserts into the iliotibial tract, with which blend both layers of its investing fascia. The tensor fasciae latae assists in flexion, abduction, and medial rotation (weakly) of the thigh. It probably aids in stabilizing the femur on the tibia, although the long, strong connection of the iliotibial tract with the lateral intermuscular septum must make direct action at the knee minimal. The superior gluteal nerve ends in the tensor fasciae latae, together with an inferior branch of the superior gluteal artery.
The piriformis muscle arises within the pelvis from the front of the sacrum between the first to fourth sacral foramina. It passes through the greater sciatic foramen to insert onto the upper border of the greater trochanter of the femur. It is a lateral rotator of the thigh and assists in abduction. Its nerves are one or two branches from S1 and S2.
The obturator internus muscle arises from the entire bony margin of the obturator foramen (except the obturator groove), the inner surface of the obturator mem- brane, and the pelvic surface of the coxal bone behind and above the obturator foramen. The fibers of the muscle converge to pass through the lesser sciatic foramen, where it is separated from the bone of the lesser sciatic notch, and then, running horizontally, ends in the medial surface of the greater trochanter of the femur above the trochanteric fossa. The muscle is a lateral rotator of the thigh and has some abduction capability. Its nerve (L5; S1, 2) also supplies the superior gemellus muscle. The tendon of the obturator internus muscle receives the superior gemellus tendon along its superior border and superficial surface and the inferior gemellus tendon along its inferior margin.
The superior and inferior gemellus muscles are small tapered muscles that lie parallel to the tendon of the internal obturator; the superior gemellus muscle above the tendon arises from the ischial spine, and the inferior gemellus muscle below the tendon arises from the ischial tuberosity. Accessories of the internal obturator muscle, the gemellus muscles have the same action. The nerve to the superior gemellus muscle comes from that to the internal obturator muscle; the nerve to the inferior gemellus is in common with the nerve to the quadratus femoris muscle.
The quadratus femoris muscle is thick and quadrilateral and is located below the inferior gemellus muscle. It arises from the upper part of the lateral border of the ischial tuberosity and inserts on the quadrate line of the femur, which extends downward from the intertrochanteric crest. This muscle is a strong lateral rotator of the thigh. Its nerve supply is from L4, 5 and S1.