642 



HUMAN ANATOMY. 



i3:??3s?>. 



Dislocated head of femur 

 Femoral artery 

 Femoral vein 



Pectineus 



Pubic bone 



way into the pelvic cavity ; or, guided by gravity, they may travel long distances 

 down the thigh before pointing. They are apt to be associated with much pain 

 because of the compression of the gluteal and other branches of the sacral plexus 

 between the bone anteriorly and the musculo- aponeurotic wall of the space posteriorly. 

 The gluteus maximus is embraced by a sheath formed by the splitting of this 

 fascia into two layers, the superficial one of which is thinner and less dense than the 

 deep layer. Abscess or hemorrhagic extravasation within the substance of that 

 muscle is, therefore, likely to give more external evidence of its presence and to be 

 less painful than if in or beneath the gluteus medius. The gluteus maximus itself 

 may be ruptured by violent exertion in extending the pelvis and trunk on the thigh, 

 the latter being fixed, as in raising a heavy weight on the back and shoulders while 

 passing from a stooping to an erect position, or in carrying a similar burden upstairs, 

 the pelvis and femur having then the same relative position at each upward step that 

 they have when the thigh is vertical and the trunk and pelvis are flexed. In the 

 erect position the muscle is relaxed. When it is paralyzed the patient can walk 

 easily on a level, but has trouble in going upstairs or in exchanging a sitting for a 

 standing posture. Wounds of the buttock without fracture of the bones may enter 

 the pelvic cavity through the sacro-sciatic foramina, and Treves has recorded a case 



of stab wound of the 

 Fig. 612. buttock in which the 



patient died from peri- 

 tonitis, the wound 

 having involved the 

 bladder and caused in- 

 traperitoneal extrava- 

 sation of urine. 



A subgluteal tri- 

 angle has been de- 

 scribed (Guiteras), the 

 boundaries of which 

 are externally the fem- 

 oral and trochanteric 

 insertion of the glu- 

 teus maximus, inter- 

 nally the long head 

 of thebiceps, the tuber 

 ischii, and part of the 

 sacro-sciatic ligament, 

 superiorly the pyri- 

 formis. The floor of 

 the triangle is made 

 by the exteAial rota- 

 tors and the adductor 

 magnus. It is the re- 

 gion of aneurism of 

 or occasional hemorrhage from the sciatic artery, of emergence of the sciatic nerve, 

 and of one form of sciatic hernia, below the pyriformis. The "triangle" is an arti- 

 ficial one, and is mentioned merely as an aid to localization of the above structures. 



The subgluteal bursae are of considerable importance. One is found interposed 

 between the trochanter and each of the gluteal muscles (page 630). Inflammation 

 and enlargement of these bursae will be followed by adduction and flexion of the 

 thigh, because active extension of the thigh, in which the glutei aid, and rotation in- 

 ward, putting them on the stretch, are painful. Flattening of the buttock and oblit- 

 eration of the gluteo-femoral crease may follow atrophy of the muscles from disease 

 (page 381). Caries of the trochanter has resulted from suppuration in these bursae. 

 The bursae over the tuberosities of the ischium frequently enlarge and may cause 

 two solid symmetrical swellings — "weavers' bottom" — which require removal. 



2. The Hip and Thigh.— The skin over the hip is less dense than over the 

 buttock, and is still thinner below Poupart's ligament and in the region of Scarpa's 



Adductor longus 



Dissection of pubic luxation of hip-joint. 



