412 



MUSCLES AND FASCIA. 



Fig. 256. Dissection of Lower 

 tremity. Posterior View. 



Ex- 



fourth, for the passage of the profunda. This muscle gives off an aponeurosis, 

 which passes in front of the femoral vessels, and joins with the Yastus Internus. 

 Relations. By its anterior surface, with the Pectineus, Adductor Brevis, Ad- 

 ductor Longus and the femoral vessels. By its posterior surface, with the great 

 sciatic nerve, the Gluteus Maximus, Biceps, Semitendinosus, and Semimembra- 

 nosus. By its superior or shortest border, it lies parallel with the Quadratus 

 Femoris. By its internal or longest border, with the Gracilis, Sartorius, and fascia 

 lata. By its external or attached border, it is inserted into the femur behind the 

 Adductor Brevis and Adductor Longus, which separate it from the Vastus 

 Internus ; and in front of the Gluteus Maximus and short head of the Biceps, 

 which separate it from the Yastus Extern us. 



Nerves. All the muscles of this group are supplied by the obturator nerve. 

 The Pectineus receives additional branches from the accessory obturator and 

 anterior crural ; and the Adductor Magnus an additional branch from the great 

 sciatic. 



Actions. The Pectineus and three Adductors adduct the thigh powerfully, 

 they are especially used in horse exercise, the flanks of the horse being grasped 

 between the knees by the action of these muscles. In consequence of the 

 obliquity of their insertion into the linea aspera, they rotate the thigh outwards, 

 assisting the external rotators, and when the limb has been adducted, they draw 



it inwards, carrying the thigh across that of 

 the opposite side. The Pectineus and Adductor 

 Brevis and Adductor Longus assist the Psoas 

 and Iliacus in flexing the thigh upon the 

 pelvis. In progression, also, all these muscles 

 assist in drawing forwards the hinder limb. 

 The Gracilis assists the Sartorius in flexing 

 the leg and drawing it inwards ; it is also an 

 Adductor of the thigh. If the lower extremi- 

 ties are fixed, these muscles may take their 

 fixed point from below and act upon the pel- 

 vis, serving to maintain the body in the erect 

 posture; or, if their action is continued, to 

 flex the pelvis forwards upon the femur. 



BACK of THIGH 



GLUTEAL KEGION. 



Gluteus Maximus. Gemellus Superior. 



Gluteus Medius. Obturator Internus. 



Gluteus Minimus. Gemellus Inferior. 



Pyriformis. Obturator Externus. 



Quadratus Femoris. 



Dissection (Fig. 256). The subject should be turned 

 on its face, a block placed beneath the pelvis to make 

 the buttocks tense, and the limbs allowed to hang over 

 the end of the table, with the foot inverted, and the 

 thigh abducted. Make an incision through the integu- 

 ment along the back part of the crest of the ilium and 

 margin of the sacrum to the tip of the coccyx, and 

 carry a second incision from that point obliquely down- 

 wards and outwards to the outer side of the thigh, four 

 inches below the great trochanter. The portion of in- 

 tegument included between these incisions, together 

 with the superficial fascia, is to be removed in the direc- 

 tion shown in the figure, when the Gluteus Maximus 

 and the dense fascia covering the Gluteus Medius will 

 be exposed. 



The Gluteus Maximus (Fig. 257), the most superficial muscle in the gluteal 

 region, is a very broad and thick fleshy mass, of a quadrilateral shape, which 



, Dissection of 



CLUTEAL REUiON 



POPLITEAL SPACE 



BACK of ICQ 



5 . SOLE of FOOT 



