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Nerve-Supply.-Obturator nerve (L. 2. 3.).
Actions. The muscle adducts and assists in flexing the thigh.
M. Adductor Brevis.-The adductor brevis is a large muscle which arises from an elongated oval surface on the front of the body and upper part of the inferior ramus of the pubic bone, surrounded by the other muscles of this group (Fig. 366).
Directed distally and laterally the muscle expands, to be inserted, by a short aponeurotic tendon, behind the insertion of the pectineus, into the distal twothirds of the line leading from the lesser trochanter of the femur to the linea aspera, and to the proximal fourth of the linea aspera itself (Fig. 365, p. 410).
FIG. 366.-MUSCLE-ATTACHMENTS TO THE OUTER SURFACE OF THE RIGHT PUBIS AND ISCHIUM.
M. Adductor Magnus.-The adductor magnus, the largest of the adductor group, is a roughly triangular muscle. It arises, mainly by fleshy fibres, by a curved origin from the lower part of the lateral border and a large portion of the adjoining inferior surface of the sciatic tuberosity, from the edge of the inferior ramus of the ischium, and from the anterior surface of the inferior ramus of the pubic bone, its most anterior fibres arising between the obturator externus and adductor brevis (Fig. 366). Its upper fibres are directed horizontally and laterally from the pubic bone towards the proximal part of the femur; the lowest fibres are directed distally from the sciatic tuberosity to the medial condyle of the femur; while the intermediate fibres radiate obliquely laterally and distally.
The muscle is inserted by tendinous fibres (1) into the space distal to the insertion of the quadratus femoris, proximal to the linea aspera; (2) into the
whole length of the linea aspera; (3) into the medial epicondylic line of the femur; (4) into the adductor tubercle on the medial condyle of the femur; and (5) into the medial intermuscular septum (Fig. 365, p. 410). The part of the muscle attached to the space proximal to the linea aspera is often separated from the rest as the adductor minimus. The attachment of the muscle to the epicondylic ridge is interrupted for the passage of the femoral vessels into the popliteal fossa. The attachment to the medial condyle is by means of a strong tendon which receives the fibres arising from the ischium (the part of the muscle associated with the hamstring group). This tendon is closely connected with the tibial collateral ligament of the knee-joint.
The muscle is covered, anteriorly, by the other adductors and by the sartorius. muscle. The profunda femoris artery separates it from the adductor longus muscle,
FIG. 367. SCHEME OF THE COURSE AND DISTRIBUTION OF THE RIGHT. OBTURATOR NERVE.
while the femoral artery is in contact with the muscle as it pursues its course through the adductor canal. The posterior surface of the muscle is in relation with the hamstring muscles.
Nerve-Supply. The adductor magnus is a double muscle, and has a double nerve-supply. The medial part of the muscle extending between the tuber ischiadicum and the medial condyle of the femur, associated with the hamstring group of muscles, derives its nerve from the nerve to the hamstring muscles, from the tibial nerve (L. 4. 5. S. 1.). This enters the muscle on its posterior surface.
The adductor portion of the muscle is supplied on its anterior surface by the deep branch of the obturator nerve (L. 3. 4.).
Actions.-The adductor magnus is an adductor and extensor of the thigh.
M. Obturator Externus.-The obturator externus is placed deeply, under cover of the previous muscles. It is a fan-shaped muscle lying horizontally in the angle between the hip bone and the neck of the femur.
It arises from the surfaces of the pubic bone and ischium, which form the inferior half of the margin of the obturator foramen, and from the corresponding
portion of the superficial surface of the obturator membrane (Figs. 366, p. 412 and 367, p. 413).
Its fibres converge towards the greater trochanter, and end in a stout tendon
which, after passing distal to and posterior to the hip-joint, Sacro-tuber is inserted into the trochanteric fossa of the greater trochanter of the femur (Figs. 365, p. 410, and 373, p. 417).
Nerve-Supply.-The deep part of the obturator nerve (L. 3. 4.).
Actions. This muscle is mainly a lateral rotator of the thigh; it QUADRATUS also flexes and adducts it.
Trigonum Femorale.The femoral triangle (O.T. Scarpa's triangle) is a large triangular space on the front of the thigh in its proximal third, which contains the femoral vessels in the proximal part of their course and the femoral nerve. It is bounded above by the inguinal ligament, laterally by the sartoriu Fascia lata and medially by the medial border of the adductor longus muscle. Its floor is formed laterally by the ilio-psoas, and medially by the pectineus, adductor longus, and a small part of the adductor brevis.
Canalis Adductorius Hunteri.The adductor canal (O.T. Hunter's canal) lies in the middle third of the (short head) medial side of the thigh, and contains the femoral vessels in the distal part of their course. It is bounded superficially by the sartorius, under which is a dense fascia (long head) derived from the fascia lata, binding together the vastus medialis, which forms the lateral wall of the canal, and the adductors, longus and magnus, which form the medial wall or floor of the canal. sides the femoral vessels and their sheath, the canal contains the saphenous nerve.
FIG. 368.-DEEP MUSCLES ON THE POSTERIOR
THE MUSCLES OF THE
This group includes the three glutei muscles, the tensor fascia latæ, piriformis, obturator internus and gemelli, and quad
The gluteus maximus and tensor fascia latæ muscles are in the same plane, invested by envelopes of the fascia lata. The gluteus medius, partially covered by the gluteus maximus, conceals the gluteus minimus; while the piriformis, obturator internus, gemelli, and quadratus femoris intervene between the gluteus maximus and the posterior surface of the hip-joint.
M. Glutæus Maximus.-The gluteus maximus is a large quadrilateral muscle, with a crescentic origin. It arises from, (1) a portion of the area on the dorsum ili above the posterior gluteal line (Fig. 369); (2) the tendon of the sacrospinalis muscle; (3) the dorsal surface of the sacrum and coccyx (Fig. 395, p. 443); and (4) the posterior surface of the sacro-tuberous ligament. The fibres which form its superior and lateral border take origin directly from the fascia lata which envelops the muscle.
The muscle forms a large fleshy mass, whose fibres are directed obliquely over the buttock, invested by the fascia lata, and are inserted, by short tendinous fibres, partly into the fascia lata over the greater trochanter of the femur (joining the ilio-tibial tract), and partly into the gluteal tuberosity (Fig. 370, p. 416). fascia lata receives the insertion of the whole of the superficial fibres of the muscle and the superior half of the deep fibres. The inferior half of the deep portion of
Gemellus superior (origin)
Gemellus inferior (origin)
Biceps and semitendinosus (origin).
Rectus femoris (reflected head of origin)
Quadratus femoris (origin)
FIG. 369. MUSCLE-ATTACHMENTS TO THE RIGHT DORSUM ILII AND TUBER ISCHIADICUM,
the muscle is inserted, for the most part, into the gluteal tuberosity; but the most inferior fibres of all are inserted into fascia lata, and are thereby connected with the lateral intermuscular septum and the origin of the short head of the biceps.
The gluteus maximus is the coarsest and heaviest muscle in the body. By its weight it helps to form the fold of the nates. It is superficial in its whole extent. The gluteus medius is visible at its superior border, covered by the fascia lata; at its lower border the hamstring muscles and sciatic nerve appear on their way to the thigh. Three bursæ are deep to it: one (not always present) over the sciatic tuberosity, a second over the lateral side of the greater trochanter, and a third over the vastus lateralis. The fibres of the gluteus maximus arising from the coccyx may form a separate muscle (agitator caudæ).
Nerve-Supply. Inferior gluteal nerve, from the sacral plexus (L. 5. S. 1. 2.).
Actions. The gluteus maximus is mainly an extensor of the thigh, and has a powerful action in straightening the lower limb, as in climbing or running. Its lower fibres also adduct the thigh and rotate it laterally.
M. Tensor Fascia Latæ.-The tensor fascia latæ arises from the iliac crest
chanter, to be inserted by a dorsal fascia
The muscle is partly superficial, partly concealed by the gluteus maximus. It covers the gluteus minimus, and the superior gluteal nerve and the deep branches of the superior gluteal artery.
Nerve-Supply. The superior gluteal nerve from the sacral plexus (L. 4. 5. S. 1.).
Actions. This muscle is a powerful abductor and medial rotator of the thigh.
M. Gluteus Minimus.The gluteus minimus arises, under cover of the gluteus
Nerve Supply. The superior gluteal nerve from the sacral plexus (L. 4. 5. S. 1.) ends in this muscle after passing between the gluteus medius and gluteus minimus.
Actions. It assists in the abduction and rotation of the thigh; and along with the gluteus maximus, by its insertion into the ilio-tibial tract, it helps to support the knee-joint in the extended position.
M. Gluteus Medius. The gluteus medius arises from (1) the dorsum ilii, between the iliac crest and posterior gluteal line above and the anterior gluteal line below (Fig. 369, p. 415), and (2) the strong fascia lata covering its surface anteriorly.
It is a fan-shaped muscle, its fibres con
TRIANGLE OF PETIT
-Sciatic nerve BICEPS (long head)
FIG. 371.-THE RIGHT GLUTEUS MAXIMUS MUSCLE.