GLUTEUS MAXIMUS 459 



The piriformis in the pelvic cavity is covered on the anterior surface by a special slightly 

 developed fascia. This fascia also covers the pelvic surface of the sacral plexus. Outside the 

 pelvis the piriformis is covered by an adherent membrane which usually is separated by loose 

 tissue from the surrounding structures. 



MUSCLES 

 I. First Layer 



The tensor fasciae latae (figs. 387, 411). — Origin. — (1) By a tendinous band from the external 

 lip of the ihac crest, and the upper part of the notch between the anterior superior and anterior 

 inferior spines of the ilium, and (2) from the septum between it and the gluteus medius. 



Structure and insertion. — The nearly parallel fibre-bundles pass distally and laterally and are 

 united to tendon fascicuU which become incorporated with the ilio-tibial band (tractus ilio- 

 tibiahs) about one-third of the way down the thigh. 



Nerve-supply. — The superior gluteal nerve sends a branch through the ventral margin of 

 the gluteus minimus to terminate in the middle third of the deep surface of the tensor fasciae 

 latae near its dorsal border. 



Action. — To rotate medially, flex, and abduct the thigh, and to make tense the fascia lata. 



Relations. — It lies over the gluteus medius, the proximal part of the rectus femoris, and the 

 vastus lateralis. 



Variations. — It may be divided into two parts, one rising from the anterior superior spine, 

 the other from the ihac crest. Accessory slips may arise from the inguinal ligament, the crest 

 of the ilium, or the fascia over the lower part of the abdominal wall. Union of the muscle with 

 the gluteus maximus has been observed, thus making a muscle much resembling the deltoid of 

 the shoulder. By some the fascia lata between the tensor and the gluteus maximus is considered 

 an atrophied part of a deltoid of the hip. 



The gluteus maximus (figs. 387, 413). — Origin. — (1) From the dorsal fifth of the outer lip 

 of the iliac crest, the outer surface of the ilium dorsal to the posterior gluteal line, the lumbo- 

 dorsal fascia between the posterior superior spine of the ilium, and the side of the sacrum, and 

 (2) from the lateral portions of the fourth and fifth sacral and the coccygeal vertebrae and from 

 the back of the sacro-tuberous (great sacro-sciatic) ligament. 



Insertion. — Into (1) the ilio-tibial band; (2) the gluteal tuberosity of the femur and the 

 adjacent part of the tendinous origin of the vastus lateralis (fig. 407). 



Structure. — The large fibre-bundles of which the muscle is composed take a somewhat 

 parallel course from origin to insertion. From the areas of origin and the enveloping fascia 

 fibrous bands extend into the muscle. The belly is divisible into two portions, a superficial and 

 a deep. The division may be much more clearly recognised in the embryo than in the adult. 

 The superficial portion is the larger, and includes all of that part of the muscle which springs 

 from the ihum and the more superficial portion of that arising from the sacrum and the upper 

 part of the coccyx. The deep portion includes that part of the muscle attached to the side of 

 the sacrum and the coccyx, and to the sacro-tuberous ligament. The superficial portion and 

 some of the fibre-bundles of the deep portion terminate in the ilio-tibial band along a line 

 extending from the great trochanter to the end of the upper third of the femur. The deep por- 

 tion is inserted chiefly by a flat tendon into the gluteal tuberosity, and also directly into the 

 adjacent portion of the origin of the vastus lateralis. 



Nerve-supply. — Two branches (inferior gluteal) arising from the sacral plexus either separately 

 or united, are usually given to the muscle. One of these curves anteriorly across the deep 

 surface of the proximal superficial portion of the muscle in the middle third between the tendons 



1. Acetabulum. 2. Annulus femorahs. 3. Annulus inguinalis subcutaneous (ext. abdominal 

 ring). 4. Arteria femoralis. 4a. A. profunda femoris. 4&. A. circumflexa femoris medialis. 

 5. A. glutea inferior. 6. A. hypogastrica (internal iliac). 7. A. iliaca externa. 8. A. 

 pudena interna (pudic). 9. Bursa ilio-pectinea. 10. B. trochanterica m. glutsei maximi. 

 11. Eminentia iliopectinea. 12. Fascia iliaca. 13. F. ilio-pectinea. 14. F. lata— a, iho- 

 tibial band. 15. F. obturatoria. 16. F. pectinea. 17. F. transversalis. 18. Femur — a, 

 trochanter major; h, trochanter minor. 19. Funiculus spermaticus (spermatic cord). 

 20. — ^Lacuna vasorum. 21. Ligamentum ilio-femorale. 22. L. inguinale (Foupart's 

 Ugament). 23. L. lacunare (Gimbernat's). 24. L. sacro-tuberosum (great sciatic). 25. 

 Musculus adductor brevis. 26. M. adductor longus. 27. M. coccygeus. 28. M. gemel- 

 lus inferior. 29. M. gluteus maximus. 30. M. gluteus medius. 31. M. gluteus 

 minimus. 32. M. iliopsoas — a, psoas; h. iliacus. 33. M. levator ani. 34. M. 

 obliquus abdominis externus, aponeurosis. 35. M. obhquus abdominis internus. 

 36. M. obturator externus. 37. M. obturator internus. 38. M. pectineus. 39. M. 

 quadratus femoris. 40. M. rectus femoris. 41. M. sartorius. 42. M. tensor fasciae 

 latae. 43. M. transversus abdominis. 44. M. transverso-spinales (multifidus). 45. M. 

 vastus lateralis. 46. N. cutaneus femoris anterior (middle cutaneous). 47. N. cutaneous 

 femoris posterior (small sciatic). 48. N. femoralis (anterior crural). 49. N. gluteus 

 superior. 50. N. ischiadicus (great sciatic) — a, peronseus communis (external pophteal) ; 

 h, tibialis (internal popliteal). 51. N. obturatorius. 52. N. pudendus. 53. N. sacraHs 

 I. 54. N. sacralis II. 55. N. saphenus. 56. Os ilium — a, spina anterior superior; h, 

 spina anterior inferior. 57. Os ischium. 58. Os pubis — a, spina (tubercle). 59. Pros- 

 tata. 60. Truncus lumbo-sacralis. 61. Vena femoralis. 62. V. saphena magna. 63. 

 V. iUaca externa. 64. V. hypogastrica (internal iliac). 65., Vertebra sacralis I. 66. 

 Vertebra sacralis II. 



