474 MYOLOGY 



Variations. The Pectineus is sometimes divided into an outer part supplied by the femoral 

 nerve and an inner part supplied by the obturator nerve. The muscle may be attached to or 

 inserted into the capsule of the hip-joint. The Adductor longus may be double, may extend to the 

 knee, or be more or less united with the Pectineus. The Adductor brevis may be divided into two 

 or three parts, or it may be united to the Adductor magnus. The Adductor magnus may be more 

 or less segmented, the anterior and superior portion is often described as a separate muscle, the 

 Adductor minimus. The muscle may be fused with the Quadratus femoris. 



Nerves. The three Adductores 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 sciatic. The Pectineus is supplied by the second, third, and fourth 

 lumbar nerves through the femoral nerve, and by the third lumbar through the accessory obturator 

 when this latter exists. Occasionally it receives a branch from the obturator nerve. 1 



Actions. The Pectineus and three Adductores adduct the thigh powerfully; they are especially 

 used in horse exercise, the sides of the saddle being grasped between the knees by the contraction 

 of these muscles. In consequence of the obliquity of their insertions into the linea aspera, they 

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

 they draw it medialward, carrying the thigh across that of the opposite side. The Pectineus 

 and Adductores brevis and longus assist the Psoas major and Iliacus in flexing the thigh upon 

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

 Gracilis assists the Sartorius in flexing the leg and rotating it inward; it is also an adductor of the 

 thigh. If the lower extremities be fixed, these muscles, taking their fixed points below, may act 

 upon the pelvis, serving to maintain the body in an erect posture; or, if their action be continued, 

 flex the pelvis forward upon the femur. 



3. The Muscles of the Gluteal Region (Fig. 434). 



Glutseus maximus. Obturator internus. 



Glutseus medius. Gemellus superior. 



Glutseus minimus. Gemellus inferior. 



Tensor fasciae latse. Quadratus femoris. 



Piriformis. Obturator externus. 



The Glutseus maximus, the most superficial muscle in the gluteal region, is a 

 broad and thick fleshy mass of a quadrilateral shape, and forms the prominence 

 of the nates. Its large size is one of the most characteristic features of the muscular 

 system in man, connected as it is with the power he has of maintaining the trunk 

 in the erect posture. The muscle is remarkably coarse in structure, being made 

 up of fasciculi lying parallel with one another and collected together into large 

 bundles separated by fibrous septa. It arises from the posterior gluteal line of 

 the ilium, and the rough portion of bone including the crest, immediately above 

 and behind it; from the posterior surface of the lower part of the sacrum and the 

 side of the coccyx; from the aponeurosis of the Sacrospinalis, the sacrotuberous 

 ligament, and the fascia (gluteal aponeurosis) covering the Glutseus medius. 

 The fibers are directed obliquely downward and lateralward; those forming the 

 upper and larger portion of the muscle, together with the superficial fibers of the 

 lower portion, end in a thick tendinous lamina, which passes across the greater 

 trochanter, and is inserted into the iliotibial band of the fascia lata; the deeper 

 fibers of the lower portion of the muscle are inserted into the gluteal tuberosity 

 between the Vastus lateralis and Adductor magnus. 



Bursse. Three bursae are usually found in relation with the deep surface of this muscle. One 

 of these, of large size, and generally multilocular, separates it from the greater trochanter; a 

 second, often wanting, is situated on the tuberosity of the ischium; a third is found between 

 the tendon of the muscle and that of the Vastus lateralis. 



The Glutseus medius is a broad, thick, radiating muscle, situated on the outer 

 surface of the pelvis. Its posterior third is covered by the Glutseus maximus, its 



1 The Pectineus may consist of two incompletely separated strata; the lateral or dorsal stratum, which is constant, 

 is supplied by a branch from the femoral nerve, or in the absence of this branch by the accessory obturator nerve; 

 the medial or ventral stratum, when present, is supplied by the obturator nerve. A. M. Paterson. Journal of Anatomy 

 and Physiology, xxvi, 43. 





