ANATOMY IN A NUTSHELL. 153 



Insertion. — (Plate LII.) — The middle slip is Inserted into the base of the 

 second phalanx: the two lateral slips, after uniting on the dorsal surface of the 



second phalanx, are continued onward and inserted into base of the third. 



Action. — Extends toes and flexes foot. 



Nekve Supply. — Fourth and fifth lumbar and first sacral through anterior 

 tibial. 



Blood Supply. — Anterior tibial. 



Peroneus tertius. — Description. — (Plate LXXV.) — This muscle is some- 

 times wanting. sometimes it is described as a fifth tendon of the Extensor longus 

 digitorum with which it is joined, and their tendons pass through the same 

 canal in the anterior annular ligament. 



Origin. — (Plate LI.) — (1) Lower fourth of anterior surface of fibula; 2 

 lower part of interosseous membrane: (o) intermuscular septum. 



Insertion. — (Plate LII.) — Inner side of dorsal surface at base of meta- 

 tarsal of little toe. 



Action. — Flexes and everts foot. 



Nerve Supply. — Fourth and fifth lumbar and first sacral through anterior 

 tibial. 



Blood Supply. — Anterior tibial. 



Gastrocnemius. — Description. — (Plate LXXVII.) — The Gastrocnemius 

 has two heads the inner of which is the larger. This muscle forms the greater 

 part of the calf of the leg and is the most superficial one in this region. An 

 aponeurosis spreads out from each tendon to cover the posterior part of that 

 portion of the muscle to which it belongs. The muscular fibers of the outer 

 head are thinner and do not extend as low as those of the inner. Muscular 

 fibers are given off from the anterior surface of these tendinous expansions. 

 This muscle gradually gets smaller and its tendon with that of the Soleus forms 

 the tendo Achillis. In the tendon of the outer head there is a sesamoid 

 fibro-cartilage (very seldom osseous): and one is occasionally found in the ten- 

 don of the inner head. 



Origin. — (Plate L.) — Inner and larger head from depression at upper and 

 back part of inner condyle and from adjacent part of femur. The outer head 

 from impression on outer side of external condyle and from posterior surface oi 

 femur immediately above the condyle. Both heads also arise by a few fibers 

 from the ridges which are continued upward from the condyle- to the linea a-- 

 pera. 



Insertion. — (Plate LII.) — Os calcis by tendo Achillis. 



Actiox. — Extends foot and flexes leg. 



Nerve Supply. — First and second sacral through internal popliteal (from 

 greal sciatic.) 



Blood Supply. — Popliteal. 



Soleus. — Description.— (Plate LXXVII.)— Situated beneath the Gastro- 

 cnemius is the Soldi-, which i> a broad flat muscle. In shape it resembles a 

 sole fish, hence its name. The deep transverse fascia of the leg, separates 

 this mucle from the posterior vessels and nerve. A- -aid before the tendon of 

 this muscle and that of the Gastrocnemius make the tendo Achillis. 



