178 THE NERVOUS SYSTEM 



supply the medial half of the sole of the foot and the medial 

 three and a half digits (cf. Median Nerve, p. 151). 



The distribution of the Lateral Plantar Nerve in the foot 

 corresponds, in a similar manner, to the distribution of the 

 ulnar nerve in the palm of the hand. It gives off numerous 

 motor branches, and its cutaneous branches supply the lateral 

 half of the sole of the foot and the lateral one and a half digits 

 (cf. Ulnar Nerve, p. 145). 



There is little of practical importance in connexion with 

 the individual muscles of the sole of the foot and, in con- 

 sequence, no description of them will be given. 



The Common Peroneal Nerve (External Popliteal) arises 

 from the sciatic in the middle of the thigh and runs distally 

 and laterally through the popliteal fossa, in close relation to 

 the tendon of the biceps. It passes behind the head of the 

 fibula and then runs forwards across the lateral aspect of the 

 neck of the bone. In both situations it can be palpated, and it 

 is therefore exposed to injury from bruising, etc. Just distal to 

 the head of the fibula, the common peroneal nerve ends by 

 dividing into the superficial (musculo-cutaneous) and the deep 

 peroneal (anterior tibial) nerves. 



In the popliteal fossa, the common peroneal gives off no 

 muscular branches, but it gives origin to two cutaneous nerves. 

 The lateral sural nerve runs forwards and distally to supply 

 the skin on the front of the leg (Fig. 7 3) ; the ramus anastom- 

 oticus peronseus (ramus communicans fibularis) passes dis- 

 tally over the lateral head of the gastrocnemius, and unites 

 with the medial sural nerve to form the nervus suralis(p. 176). 



The Superficial Peroneal (Musculo - cutaneous) Nerve 

 enters the lateral compartment of the leg and supplies the 

 peronaeus longus and brevis. It pierces the deep fascia at the 

 junction of the distal and middle thirds of the leg, and is con- 

 tinued on to the dorsum of the foot, to which it supplies some 

 small cutaneous filaments. Its terminal branches supply the 

 medial side of the hallux and the contiguous sides of the 

 second, third, fourth and fifth toes (Fig. 73). 



