MUSCLES OE THE HIND LIMB. 



103 



Fi^. 86. 



internally in a concave aponeurotic arch : the second head is a thin, 

 tendinous slip, "arising* from the common tendon of the triceps as 

 this lies on the knee-joint. The muscle is thickest near its origin, 

 and then gradually diminishes in size as it passes backwards ; the 

 superficial sm^face is convex, the deep surface is flat. By tracing the 

 tendons of orig-in, they are seen soon to unite and form a common 

 flat tendinoiis surface, broad in front, 

 contracted behind ; this aponeurosis 

 lies in a plane running obliquely 

 from the deep surface towards the 

 superficial surface, without, how- 

 ever, reaching" this. The muscular 

 fibres arise from both surfaces of the 

 aponeurosis, the fibres of the two 

 sides diverging slightly as they pass 

 backwards so as to be inclined at a 

 small ang'le to each other. The 

 fibres are inserted into a fibrous ex- 

 pansion [Ajj) which lies on the su- 

 perficial surface of the muscle; thin 

 and slight in front, this aponeurosis 

 rapidly thickens posteriorly until it 

 passes into the tendo Achi/li-s. 



128. M. tlhlalis posticus (Fig-. 

 86 t.p.). 



Dugès, cruro-astragalien, n. i6o. 



Covered by the gastrocnemius this 



M. vastus externus. 

 M. vastus internus. 



