TRICEPS EXTENSOR 



263 



Relations. The heads of the gastrocnemius muscle form the inferior boundaries of the 

 popliteal space, and are placed between the hamstring muscles : the peroneal nerve is lodged 

 between the external head and the biceps. The gastrocnemius lies over the popliteus, 

 plantaris and soleus muscles, with the popliteal vessels and internal popliteal nerve. The 

 short saphenous vein is placed over, and the tibial communicating nerve descends in, the 

 interval between its two heads. 



Varieties. The gastrocnemius is not unfrequently joined by a bundle of muscular fibres 



Fig. 257. SUPERFICIAL MUSCLES OF THE LEG, 

 SEEN FROM THE INNER SIDE. (After Bourgery.) | 



1, vastus internus ; 2, sartorius ; 2', its tendon, 

 spreading on the inner upper part of the tibia; 

 3, gracilis ; 4, semitendinosus ; 4', its insertion ; 

 and between 2' and 4', that of the gracilis ; 5, semi- 

 membranosus ; 6, inner head of the gastrocnemius ; 

 7, soleus ; 8, 8', placed upon the tendo Achillis, 

 point to the tendon of the plantaris descending on 

 the inner side ; 9, small part of the tendon of the 

 tibialis posticus ; 10, flexor longus digitorum ; 11, 

 flexor longus hallucis ; 12, tibialis anticus ; 12', its 

 tendon of insertion ; 13 ; abductor hallucis. 



which arises separately from some part of the 

 popliteal surface of the femur. This bundle 

 has been seen passing between the popliteal 

 artery and vein. Absence of the outer head, 

 or even of the whole muscle, has also been 

 observed. 



The soleus muscle arises externally 

 from the posterior surface of the head and 

 upper third of the shaft of the fibula ; 

 internally from the oblique line and the 

 internal border of the tibia, as far down 

 as the middle of the bone ; and bet wee 11 

 the tibia and fibula, from a tendinous 

 band which arches over the popliteal vessels 

 and nerve. The muscular fibres spring 

 in part from the bones, but to a much 

 greater extent from two tendinous laminae 

 which descend, the outer from the fibula, 

 and the inner from the arch over the vessels 

 and the oblique line of the tibia, in the 

 substance of the muscle, on the front sur- 

 face of which each appears by one edge, 

 the opposite edge being directed obliquely 

 towards the middle line of the leg. The 

 fibres from the anterior surfaces of these 

 laminae converge to a median tendinous 



septum which also appears on the front of the muscle by one border, while those 

 arising from their posterior surfaces are directed downwards and backwards, and end 

 in an aponeurosis which covers the greater part of the posterior surface of the mass, 

 and over which the tendinous surface of the gastrocnemius glides. The tendon of 

 insertion is prolonged downwards from this aponeurosis, being joined anteriorly by 

 the median septum, and forms the deeper and larger part of the tendo Achillis. 

 The fasciculi of the muscle are numerous and short, having a length of at most 

 from two to three inches, and they are continued downwards on the deep surface of 

 the tendo Achillis to within a short distance of the heel. 



