350 THE MUSCLES 



inwards, it is continuous with the })ul)ic i)ortion of the fascia lata which invests the 

 pectineus muscle, and it also sends backwards a septum between the psoas and the 

 pectineus which is attached to the ilio-pubal ridge. 



3. SARTORIUS 



The sartorius — named somewhat erroneously from sartor, a tailor, Ijecause it 

 has been supposed to be the muscle by which the cross-legged sitting posture is 

 produced — is a long, ribbon-shaped muscle slightly fusiform at the two ends. 



Origin. — The anterior superior spine of the ilium and the adjacent part of the 

 notch lu'tween this process and the anterior inferior spine. 



Insertion. — (1) The front part of the inner surface of the tibia, just internal to 

 the tubercle; (2) the upper part of the deep fascia covering the internal surface of 

 the leg. 



Structure. — Arising by short tendinous fi])res, the fleshy fibres which are the 

 longest in the whole body, run parallel to one another inwards and downwards 

 across the front of the thigh, and after reaching the inner surface of the thigh a) )OUt 

 the middle, the muscular band runs almost vertically downwards to the back of the 

 internal condyle of the femur. At this point the tendon of insertion makes its 

 appearance as an aponeurosis which covers the deep asj^ect of the muscle and 

 becomes free from fleshy fibres just below the knee-joint, where it turns forwards 

 and covers the inner surface of the inner tuberosity of the tibia, being separated 

 from it as well as from the tendons of the gracilis and semi-tendinosus by a large 

 bursa. The upper border of this aponeurosis is thick and tendinous and is inserted 

 directly into the bone. The lower part of the aponeurosis, which is of a much 

 more membranous character, is continued downwards and forwards and blends with 

 the deep fascia of the inner side of the leg, of which it is one of the chief con- 

 stituents. 



Nerve-supply. — From the second, third, and fourth iDranches of the luml^ar 

 plexus,' by filaments which are usually derived from the middle cutaneous branch 

 of the anterior crural nerve as it pierces the muscle at the junction of its middle and 

 upper thirds. 



Action. — (1) To flex the thigh, and at the same time rotate it slightly outwards 

 and abduct it. (2) To flex the knee, and when the knee is in the ])ent position it 

 will also help in rotating the leg inwards. (3) Being contained in the close-fitting 

 sheath formed l)v the fascia lata and its deep processes, it will tend when it con- 

 tracts to draw the soft parts upon the inner surface of the thigh forwards, and so 

 make tense the inner portion of the fascia lata. (4) Acting from below, it will flex 

 the pelvis upon the thigh. 



Relations. — In front above lies the fascia lata; internally below lie the fascia 

 lata and intei-nal saphenous vein; Ijeneath lie the rectus femoris, iliacus, pectineus, 

 adductor longus and magnus, vastus internus, and the inner hamstring tendons, the 

 femoral vessels, the anterior crural nerve and its internal saphenous and vastus 

 internus brandies. 



Variations. — The sartorius is occasionally absent ; it may also he divided longitudinally. It 

 may have insertions into the fascia lata, or the ligamentum patellae. A tendinous intersection 

 sometimes crosses the muscle. 



4. PECTINEUS 



The pectineus — named from peden ( = pubes) on account of its origin from 

 that })on( — is a (luadrilateral sheet. 



Origin. — (1) The ilio-pectineal line between the spine of the pubes and the ilio- 

 pul)al ridge; (2) the surface in fn^it of the inner end of this line; and (S) the deep 

 surface of the pubic portion of the fascia lata close to its attachment to the ilio- 

 pectincnl line. 



Insertion. — The back of the femur in a vortical line about two inches (5 cm.) 

 long, beginning just Ijehind the lesser trochanter. 



