212 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 



Fig. 294. — Superficial layer of the posterior muscles of the hip. 

 The portion of the superficial layer of the fascia lata which covers the tensor fasciae latas has been removed. * = posi- 

 tion of greater trochanter. 



Fig. 295. — Middle layer of the posterior muscles of the thigh. 

 The glutaeus maximus has been divided and reflected. 



margin of the glutaeus maximus. The insertion conceals the tendinous origin of the vastus later- 

 alis from the trochanter major. The tendon of insertion is separated from the great trochanter 

 by a large bursa, the trochanteric bursa (Fig. 295), beneath which there is usually one or two addi- 

 tional bursae, the gluteo femoral bursa or bursa (Fig. 295). About half of the glutaeus medius, 

 the piriformis, the obturator internus and gemelli, the quadratus femoris, and the adductor mini- 

 mus are covered by the glutaeus maximus. 



The glutaeus maximus is supplied by the inferior gluteal nerve. It extends the thigh and is the antagonist of the 

 iliopsoas. 



The glutaeus medius (Figs. 293, 295) is also a strong, flat, thick muscle, part of which is 

 concealed by the glutaeus maximus, the remainder of it (Fig. 294) being situated in the upper glu- 

 teal region directly beneath the gluteal fascia, to which it is adherent. It arises from the outer 

 surface of the ilium (Fig. 293), in the area between the anterior gluteal line, the iliac crest, and 

 the posterior gluteal line, and from the gluteal fascia. The fibers of the muscle converge toward 

 the greater trochanter, the posterior fasciculi being more or less independent and passing obliquely 

 downward and outward , the middle fibers running directly downward and the anterior ones down- 

 ward and inward. The short and broad tendon of insertion is attached to the outer portion of 

 the greater trochanter (Fig. 295), extending upward as far as the tip of this process. 



While the greater portion of the glutaeus medius is covered by the glutaeus maximus, it in turn 

 completely conceals the glutaeus minimus, and its posterior margin is usually in immediate rela- 

 tion with the upper margin of the piriformis. Beneath its insertion there is usually situated a 

 bursa, the posterior bursa of the gluteus medius (Fig. 301). 



The muscle is supplied by the superior gluteal nerve. It abducts the thigh; the larger anterior portion also acts as 

 an internal rotator, the posterior portion (frequently characterized by a species of intermediate tendon and by a different 

 direction of its fibers) also as an external rotator. 



The glutaeus minimus (Figs. 293, 301, and 302) is a flat, broad, fan-like muscle which lies 

 upon the outer surface of the ala of the ilium and the postero-superior aspect of the articular cap- 

 sule of the hip-joint. It arises from the posterior surface of the ilium between the anterior and 

 inferior gluteal lines (Fig. 293), and the fibers converge from all sides toward the greater tro- 

 chanter. In the middle of its course the muscle develops a broad aponeurosis which passes 

 directly into a short broad tendon. The insertion is into the tip and inner border of the great 

 trochanter. 



The glutaeus minimus, like the medius, is supplied by the superior gluteal nerve. It also has a similar function 

 (abduction). 



The piriformis (Figs. 295, 298, and 300 to 302) is a decidedly conical muscle which is 

 usually in immediate relation with the posterior border of the glutaeus medius. Its insertion is 



