H02 Till- Ml >. / BS 



in front f tho superior extremity of the principal metatarsi il bone. 

 with the analogous branch of the tendinous division (Fig. 13G, 8). The 

 other ramification is directed to tho inside of tho tarsus, to bo attu-lie.1 to 

 tho second cuneiform bone (Fig. 136, 7). 



Relations. In front, with the tendinous portion of the muscle and tho 

 anterior extensor of tho phalanges ; behind, with tho external face of the 

 tibia. Tho tendon, after traversing tho annular ligament of the, cord, mycrs 

 the mctatarsal branch of tho latter, and is in turn covered by the anterior 

 extensor. 



Action. It is an active agent in flexing the foot on the leg. 



B. Posterior Tibial Region. 



This region comprises six muscles, which are arranged in two super- 

 posed layers behind the tibia. The superficial layer is formed by the 

 gastrocnemius, soleus, and the superficial flexor of the phalanges. The <1< \> 

 layer is composed of the popliteus, tho deep flexor, and tho oblique flexor of 

 the phalanges. 



1. Gatttrocnemii, or Gemelli of the Tibia. (Figs. 135, 22 ; 137, 20.) 

 Synonyms. Bifcraoro-calcaneus Girard. (Gastrocnemius externus Percivall.) 



Situation Composition Extent. The gomclliof the leg, situated behind 

 tho femoro-tibial articulation, below tho ischio-tibial muscles, constitute 

 two thick fleshy fasciculi distinct from one another only at their superior 

 extremity, being confounded for tho remainder of their extent, and continued 

 inferiorly by a single tendon which extends to tho point of the calcis. 



Form Structure. Both of these muscular masses arc flattened on both 

 sides, thick in the middle, narrow at tho extremities, and intersected by 

 strong tendinous bands. By their union they form a wide channel, open 

 in front, which embraces the femoro-tibial articulation and the muscles of 

 the deep layer. 



The tendon, at first fasciculated, then single and funicular, receives that of 

 the soleus, and is reinforced by a fasciculus from the fibrous band annexed in 

 front to the tendon of the perforatus (see the description of the tibia! aponeu- 

 rosis, p. 297). An aponeurotic lamina which covers the external gemellus, 

 is continued downwards, partly with this fibrous band, and partly with the 

 tendon of the muscle itself. 



Attachments. The external gcmellus arises on the femur, from the 

 nigged lip which margins in front the supracondyloid fossae; the internal, 

 from the collection of tubercles which constitutes the crest of tho same 

 name. The terminal tendon of tho two bellies is fixed on the summit of 

 the calcis, not at its anterior part, but posteriorly, this being lubricated by a 

 vesicular synovial membrane forming a gliding surface on which tho tendon 

 rests during extreme flexion of the foot (Fig. 67, 1). 



Relations. The gemelli respond : by their superficial face, to tho three 

 ischio-tibial muscles, and the tibial aponeurosis; by their deep face, to 

 tho perforatus, which contracts intimate adhesions with the vastus 

 externus, to tho posterior ligament of tho femoro-tibial articulation, the 

 popliteal muscle and vessels, the great sciatic nerve, and the oblique and deep 

 flexor muscles of tho phalanges. The tendon lies beside that of the per- 

 foratns, which is twisted around and completely envelopes it at its inferior 

 extremity, in common with tho fibrous band from the tibial aponeurosis. 

 The two tendons form what is usually termed the tendon of the hock, or 

 tendon of Achilles. 





