THE MUSCC'LO-CUTANEOUS NERVE. 



621 



(<Z) The external branch, larger than the internal one, descends over the foot 

 towards the fourth toe, which, together wdth the contiguous borders of the third 

 and fifth toes, it supplies with branches. Cutaneous nen-es. derived from this 

 branch, spread over the outer ankle and the outer side of the foot, where thev are 

 connected with the short saphenous nerve. 



380. 



Fig. -380. — View op the Distributiok op the 

 Branches of the External Popliteal Nerve in 

 THE Front of the Leg and Dorsum of the Foot 

 (after Hirschfeld and Leveille"). 



The upper part of tlie peroneus longiis muscle has 

 been removed, the tibialis anticus, the long extensor of 

 the gi'cat toe and the peroneus longus have been drawn 

 separate in the leg by hooks marked a, h, and c, and 

 tlie tendons of the extensor muscles have beer removed 

 in the dorsum of the foot, to show the deeper seated 

 nerves ; 1, the external popliteal or peroneal nerve 

 winding round the other part of the fibula ; 1', its 

 recuri'ent articular branches exposed by the dissection 

 of the upper jjart of the tibialis anticus muscle ; 2, 2, 

 the musculo-cntaneous neive ; 2', 2', twigs to the long 

 and short peroneal muscles ; 3, internal liranch of the 

 musculo-cutaueous nerve ; 3', 3', its dorsal digital 

 branches to the inside of the great toe, and to the 

 adjacent sides of the second and third toes ; 4, the 

 external branch ; 4', 4', its dorsal digital branches to 

 the adjacent sides of the tliird and fourth toes, and in 

 part to the space between the fourth and fifth toes ; 

 5, the extei'nal saphenous nerve descending on the 

 outer border of the foot, and uniting at two places 

 vd^h the outer branch of the nuisculo-cutaneous ; 5', 

 its branch to the outer side of the fifth toe ; 6, placed 

 on the upper part of the extensor communis digitorum, 

 marks the anterior tibial nerve passing beneath the 

 muscles ; 6, placed fiuther down on the tendon of the 

 tibialis anticus, points to the nerve as it crosses to 

 the inside of the anterior tibial artery ; 6', its muscidar 

 branches in the leg; 6", on the tendon of the extensor 

 longus pollicis points to the anterior tibial neive after 

 it has passed into the foot behind that tendon ; 7, 

 its inner branch uniting with a twig of the musculo- 

 cutaneous, and giving the dorsal digital nerves to the 

 adjacent sides of the first and second toes ; 8, distri- 

 bution of its outer branch to the extensor brevis digi- 

 torum and tarsal articulations. 



Tlie dorsal digital nerves are continued on to 

 the last phalanges of the toes. 



The number of toes supplied by each of the two 

 divisions of the musculo -cutaneous nerve is liable to vary ; together these nerves 

 commonly supply all the toes on the dorsal aspect, excepting the outer side of 

 the little toe. which receives a branch from the short saphenous nerve, and the 

 adjacent sides of the great toe and the second toe, to which the anterior tibial 

 nerve is distributed : with this latter branch, however, it generally communicates. 



Anterior Tibial Nerve. — The anterior tibial (interosseous nerve), 

 commencing between the fibula and the peroneus longus, inclines ob- 

 liquely beneath the long extensor of the toes to the fore part of the 

 interosseous membrane, and there comes into contact with the anterior 

 tibial vessels, and with those vessels it descends to the front of the 

 ankle-joint, -where it divides into an external and an internal branch. 



