156 MUSCULAR SYSTEM. 



by d broad expanded aponeurosis. The inferior division is, at its 

 upper part, united with the next muscle by intermixture of fleshy 

 fibres. 



Action. — The two divisions of this muscle will operate dif- 

 ferently. The anterior or superior one will assist the rectus and 

 vasti in extending the thigh ; but the posterior one will contri- 

 bute towards its flexion. They will both co-operate in abducting 

 the limb ; also in rotating it inwards — the hock at the time 

 turning outwards. 



p;mitendinosus. 7 



> adductor tibialis, 

 emimembranosus. ) 



Ischio-tibialis Internus. 



Situation. — Posterior side of the haunch and thigh. 



Attachment. — Superiorly, to the postero-lateral part of the spine 

 of the sacrum ; to the two or three uppermost bones of the coccyx ; 

 and to the antero-inferior side of the tuberosity of the ischium. 

 ]nferiorly, to the superior and antero-internal part of the tibia; 

 directly opposite to the attachment of the lower head of the biceps 

 abductor and tibial aponeurosis. 



Relations. — Posteriorly, with the faschia and skin ; anteriorly, 

 with the tuberosity of the ischium, os femoris, and gastrocne- 

 mii ; externally, with the biceps ; internally, with the adductor 

 tibialis. 



Structure, — This is a long cyhndroid muscle, composed of 

 two parts, one coming from the sacrum, the other from the 

 ischium ; both of which are united below the tuberosity. The 

 superior attachments are both fleshy and tendinous. From the 

 inferior proceeds an aponeurotic expansion, contributing towards 

 the tibial fasciiia. 



MUSCLES OF THE THIGH AND LEG. 

 These muscles are invested and confined down in their places 

 by the crural or tibial faschia, which is in part an extension from 

 the faschia lata, and in part a production from those femoral 

 muscles whose tendons or aponeuroses descend upon the leg ; 

 such as the adductor magnus, biceps, and adductor tibialis. 

 The muscles themselves (those now under consideration), being 

 collected together into two packets or parcels, separate and dis- 

 tinct from each other, the crural faschia admits of an anterior 

 and a posterior portion ; one investing the muscles in the ante- 

 rior crural region, the other in the correspondent posterior re- 

 gion. The former has for its principal places of attachment the 

 patella ; the upper and lower ends, tubercle, and spine of the 

 tibia : and the anterior annular and lateral ligaments of the 



