262 



THE MUSCLES OF THE LOWER LIMB. 



descend, the one lying on the surface of the other, to be inserted by a common 

 tendon the tendo Achillis ; the third, a small muscle, the plantaris, passes down- 

 wards between the other two. 



The gastrocnemiusjmuscle consists of two large heads which spring from the 

 lower end of the femur, and terminate about the middle of the leg in a common 



Fig. 256. SUPERFICIAL MUSCLES OP THE LEG, SEEN FROM 

 BEHIND. (After Bourgery.) I 



1, rastus externus : 2, biceps flexor cruris ; 3, semitendinosus ; 

 4, semimembranosus ; 5, gracilis ; 6, sartorius ; 7, outer, and 8, 

 inner head of the gastrocnemius ; 9, placed in the popliteal space, 

 points to the plantaris ; 9', its thin tendon on the inner side of the 

 tendo Achillis ; 10, 10, fibres of the soleus descending to the flat 

 tendon which, joining with that of the gastrocnemius, forms, + + , 

 the tendo Achillis ; 11, peroneus longus ; 12, peroneus brevis ; 

 13, flexor longus digitorum ; 14, tibialis posticus ; 15. points to the 

 lower fibres of the flexor longus hallucis, the tendon of which is 

 seen descending orer the tibia at 15'. 



tendon. The outer head arises from a depression on 

 the outer side of the external condyle above the 

 tuberosity, and from the hinder surface of the femur 

 immediately above the condyle. The inner head arises 

 from an impression on the upper part of the internal 

 condyle, close behind the adductor tubercle, from the 

 lower end of the internal supracondylar ridge, and 

 from an adjoining roughened part of the popliteal 

 surface of the femur. The lateral part of each origin 

 takes place by means of a strong tendon which is 

 attached to the impression on the condyle, and spreads 

 out as it descends on the surface of the head ; while the 

 central part arises by short tendinous fibres, which are 

 succeeded by a prominent fleshy mass extending along 

 the part of the head next to the middle line of the 

 limb. The two heads enlarge downwards as fresh fibres 

 are added from the superficial tendons, and their 

 adjacent borders converge and soon meet, but do not 

 join, being separated superficially by a longitudinal 

 groove, and deeply by a thin tendinous band which is 

 seen when the fleshy fibres are drawn aside. The 

 short muscular bundles incline forwards, and end 

 obliquely on the posterior surface of the inferior 

 tendon, which is broad and aponeurotic as it occupies 

 the deep surface of the muscle, but becomes narrower 

 and thicker as it proceeds downwards to be united 

 with the subjacent tendon of the soleus in the tendo Achillis. 



The lower edge of each muscular part presents a convexity downwards ; and the 

 inner head, besides being broader and thicker, also descends lower than the outer. 

 A synovial bursa, frequently communicating with the knee-joint, lies beneath the 

 inner head of origin, and separates it from the tendon of the semimembranosus 

 muscle ; and above this, between the tendon and the femur, there is usually a second 

 smaller sac, which may also open into the joint. 1 In the outer head a sesamoid 

 fibro- cartilage or bone is sometimes met with over the condyle of the femur. 



1 Gruber, "Die Knieschleimbeutel, " Prag, 1857. 



