THE ABDOMINAL WALLS. 113 



Posterior branch of external cutaneous nerve, 851. (832) 

 Reflected branches of the small sciatic nerve, 857. (837) 



The long pudendal nerve. 



Perforating cutaneous branch of fourth sacral nerve, 853. (834) 

 Lymphatics of the gluteal region, 705. (689) 

 Remove the fascia, fat, and connective tissue and expose the gluteus maximus. 



Gluteus maximus, 371-2-3 (370-1-2) ; P. 392 ; Fig. 291. (390) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 



Divide the gluteus maximus near its origin, beginning at the anterior border, and turn it downward and 

 outward to the insertion ; much care is required to raise and turn off the muscle without injury to the 

 underlying structures. A number of vessels and nerves will be seen entering the inner surface of the 

 muscle ; these should be carefully divided close to the muscle, as it is reflected to the insertion. 



The inferior gluteal nerve, 855. (835-6) 

 Superficial branch of the gluteal artery, 603. (591) 

 Gluteus medius, 373-4; Fig. 288. (372-3) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 



Beginning at the posterior border, divide the gluteus medius about two inches below the origin, turn the 

 lower portion down to the insertion, carefully raise the upper portion to the origin and expose the struc- 

 tures underneath. 



Deep branch of the gluteal artery, 604 : Fig. 369. (592) 



Superior. Inferior branch. 

 Superior gluteal nerve, 854-5. (835) 

 Gluteus minimus, 374-5 ; Fi g- 2 9- (373~4) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 



Disarticulate the pelvis and lower extremity from the trunk, dividing the spine between the third and 

 fourth lumbar vertebrae. Divide the pelvis, cutting one-half an inch to the left of the median line in 

 front and behind. 



Pyriformis, 375-6-7; Fig. 288. (374) 



(Origin.) Insertion. Structure. Nerve-supply. Action. Relations. Variations. 

 Sciatic artery, 607-8 ; Fig. 369. (595-6) 

 Branches of the sciatic artery : 

 Intrapelvic branches. 

 Extrapelvic brandies : 



Coccygeal. Inferior gluteal. Muscular branches. 

 Anastomotic branch, crucial anastomosis. 

 Articular branches. Cutaneous branches. 

 Comes nervi ischiatici. 



Small sciatic nerve, 856-7 ; Fig. 467. (837) 

 Great sciatic nerve, 858 ; Fig. 467. (838-9) 

 Internal pudic artery, 608. (596-7) 



As it crosses the spine of the ischium : 



Branches of the artery. 



The pudic nerve accompanies the artery, 857. (838) 

 Obturator internus and gemelli, 377-8 ; Fig. 288. (374-5-6-7) 

 Obturator internus : 



Origin. Insertion. Structure. Nerve-supply. 

 Gemellus superior : 



Origin. Insertion. Structure. Nerve-supply. 

 Gemellus inferior : 



Origin. Insertion. Structure. Nerve-supply. 

 Action. Relations. Variations. 

 Quadratus femoris, 378-9 ; Fig. 288. (377) 



Origin. Insertion. Structure. Nerve-supply. Action. Relations. Variations. 

 Obturator externus, 383-4. (382) 



Insertion. (The muscle will be shown later.) 



The parietal structures of the pelvic cavity not already fully exposed, should now be demonstrated. 



