THE GLUTEAL REGION 517 



artery passing between them; by its internal or longer 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 femoris, which separate it from the Vastus externus. 



Nerves. The three Adductor muscles and the Gracilis are supplied by the third and fourth 

 lumbar nerves through the obturator nerve; the Adductor magnus receiving an additional 

 branch from the sacral plexus through the great sciatic. The Pectineus is supplied by the 

 second, third, and fourth lumbar nerves through the femoral, and by the accessory obturator, 

 from the third lumbar, when it exists. Occasionally it receives a branch from the obturator 

 nerve. 1 



Actions. The Pectineus and three Adductors adduct the thigh powerfully, they are espe- 

 cially used in horseback riding, the flanks of the horse being grasped between the knees by the 

 actions of these muscles. In consequence of the obliquity of their insertion into the linea aspera 

 they rotate the thigh outward, assisting the external Rotators, and when the limb has been 

 abducted they draw it inward, carrying the thigh across that of the opposite side. The Pec- 

 tineus and Adductor brevis and longus assist the Psoas and Iliacus in flexing the thigh upon the 

 pelvis. In progression, also, all these muscles assist in drawing forward the hinder limb. The 

 Gracilis assists the Sartorius in flexing the leg; it is also an adductor of the thigh. If the lower 

 extremities are fixed, these muscles may take their fixed point from below and act upon the pelvis, 

 serving to maintain the body in an erect posture, or, if their action is continued, to flex the pelvis 

 forward upon the femur. 



Hunter's Canal (canalis addudorius [Hunteri]) extends from the apex of Scarpa's triangle to 

 the opening in the Adductor magnus muscle. Tho n.n.tcrn-i.nti'rnnl boundfirii or roof of Hunter's 

 canal is the Sartorius and the aponeurotic expansion from the Adductors to the Vastus internus. 

 It is bounded externally by the Vastus internus. The Adductor longus and magnus constitute 

 its floor or the postero-internal boundary^ The canal contains the femoral artery, femoral vein, 

 the long saphenous nerve, and the nerve to the Vastus internus. 



Applied Anatomy. The Adductor longus is liable to be severely strained in those who ride 

 much on horseback, or its tendons to be ruptured by suddenly gripping the saddle. Occasionally, 

 especially in cowboys and cavalry soldiers, the tendon of insertion of the Adductor magnus 

 may become ossified, constituting the rider's bone. 



III. MUSCLES AND FASCIA OF THE HIP. 

 3. The Gluteal Region (Figs. 387, 388). 



Glutens maximus. Obturator internus. 



Gluteus medius. <^- Gemellus superior. 



Gluteus minimus. ^ Gemellus inferior. 



Pyriformis. Quadratus femoris. 



Obturator externus. 



Dissection (Fig. 386). 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 integument along 

 the crest of the ilium to the middle of the sacrum, and thence downward to the tip of the coccyx, 

 and carry a second incision from that point obliquely downward and outward to^ the outer side 

 of the thigh, four inches below the great trochanter. The portion of integument included between 

 these incisions is to be removed in the direction shown in the figure. 



The Gluteus maximus (m. glutaeus maximus} (Fig. 387), the most superficial 

 muscle in the gluteal region, is a very broad and thick, fleshy mass of a quadri- 

 lateral shape, which forms the prominence of the buttock. Its large size is one 

 of the most characteristic points in the muscular system of man, connected as it 

 is with the power he has of maintaining the trunk in the erect posture. In structure 

 the muscle is remarkably coarse, being made up of muscle fasciculi lying parallel 



1 Professor Paterson describes the Pectineus as consisting of two incompletely separated strata, of which 

 the outer or dorsal stratum, which is constant, is supplied by the femoral nerve, or in its absence by the acces- 

 sory obturator, with which it is intimately related; while the inner or ventral stratum, when present, is supplied 

 by the obturator nerve. Journ. of Anat. and Phys., vol. xxvi, p. 43. 



