412 



THE MUSCULAR SYSTEM. 



Nerve-Supply. Obturator nerve (L. 2. 3.). 



Actions. The muscle adducts and assists in flexing the thigh. 





M. Adductor Brevis. The adductor brevis is a large muscle which arises 

 from an elongated oval surface on the front of the body and upper part of the 

 inferior ramus of the pubic bone, surrounded by the other muscles of this group 

 (Fig. 366). 



Directed distally and laterally the muscle expands, to be inserted, by a short 

 appneurotio tendon, behind the insertion of the pectineus, into the distal two- 

 thirds of the line leading from the lesser trochanter of the femur to the linea 

 aspera, and to the proximal fourth of the linea aspera itself (Fig. 365, p. 410). 



Nerve-Supply. Obturator nerve (L. 2. 3. 4.). 

 Actions. The muscle adducts and flexes the thigh. 



Kectus femoris (straight head of origin) 



Rectus femoris (reflected head of origin) 

 Attachment of ilio-femoral ligament 



Pyramidalis abdominis (origin) 

 \Rectus abdominis (origin) 



Gracilis (origin) 



Adductor brevis 

 (origin) 



Semimembranosus 

 (origin) 



Quadratus femoris 

 (origin) 



Biceps and semitendin- 

 osus (origin) 



FIG. 366. MUSCLE- ATTACHMENTS TO THE OUTER SURFACE OF THE EIGHT PUBIS AND ISCHIUM. 



M. Adductor Magnus. The adductor magnus, the largest of the adductor 

 group, is a roughly triangular muscle. It arises, mainly by fleshy fibres, by a curved 

 origin from the lower part of the lateral border and a large portion of the adjoin- 

 ing inferior surface of the sciatic tuberosity, from the edge of the inferior ramus i 

 of the ischium, and from the anterior surface of the inferior ramus of the pubic i 

 bone, its most anterior fibres arising between the obturator externus and adductor 

 brevis (Fig. 366). Its upper fibres are directed horizontally and laterally froni' 

 the pubic bone towards the proximal part of the femur; the lowest fibres are, 

 directed distally from the sciatic tuberosity to the medial condyle of the femur j 

 while the intermediate, fibres radiate obliquely laterally and distally. 



The muscle is inserted by tendinous fibres (1) into the space distal to the 

 insertion of the quadratus femoris, proximal to the linea aspera; (2) into thffi 



