THE TIBIAL AND MUSCULO-CUTANEOUS NERVES. 865 



superior and inferior external articular arteries to the outer side of the knee. The 

 upper one occasionally arises from the great sciatic nerve before its bifurcation. 

 The third (recurrent) articular nerve is given off at the point of division of the 

 peroneal nerve ; it ascends with the anterior recurrent tibial artery through the 

 Tibialis anticus muscle to the front of the knee, which it supplies. 



The cut'incons branches, two or three in number, supply the integument along 

 the back part and outer side of the leg as far as its middle or lower, part ; one of 

 these, larger than the rest, the communicant peronei, arises near the head of the 

 fibula, crosses the external head of the Gastrocnemius to the middle of the 

 leg. and joins with the communicans poplitei to form the external saphenous. 

 This nerve occasionally exists as a separate branch, which is continued down as 

 far as the heel. 



The Anterior Tibial Nerve (Fig. 506) commences at the bifurcation of the per- 

 oneal nerve, between the fibula and upper part of the Peroneus longus, passes 

 obliquely forward beneath the Extensor longus digitorum to the fore part of the 

 interosseous membrane, and reaches the outer side of the anterior tibial arterv 

 above the middle of the leg; it then descends with the artery to the front of the 

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

 lies at first on the outer side of the anterior tibial artery, then in front of it, and 

 again at its outer side at the ankle-joint. 



The branches of the anterior tibial nerve in its course through the leg are the 

 muscular branches to the Tibialis anticus, Extensor longus digitorum, Peroneus 

 tertius. and Extensor proprius hallucis muscles, and an articular branch to the 

 ankle-joint. 



The external or tarsal branch of the anterior tibial passes outward across the 

 tarsus, beneath the Extensor brevis digitorum, and, having become ganglionic, 

 like the posterior interosseous nerve at the wrist, supplies the Extensor brevis 

 digitorum. From the ganglion are given off three minute interosseous branches 

 which supply the tarsal joints and the metatarso-phalangeal joints of the second, 

 third, and fourth toes. The first of these sends a filament to the second dorsal 

 in'erosseous muscle. 



The internal branch, the continuation of the nerve, accompanies the dorsalis 

 pedis artery along the inner side of the dorsum of the foot, and at the first inter- 

 osseous space divides into two branches, which supply the adjacent sides of the 

 great and second toes, communicating with the internal branch of the musculo- 

 cutaneous nerve. Before it divides it gives off an interosseous branch to the first 

 space, which supplies the metatarso-phalangeal joint of the great toe and sends a 

 filament to the First dorsal interosseous muscle. 



The Musculo-cutaneous Nerve (Fig. 506) supplies the muscles on the fibular 

 side of the leg and the integument of the dorsum of the foot. It passes forward 

 betAveen the Peronei muscles and the Extensor longus digitorum, pierces the deep 

 fascia at the lower third of the leg on its front and outer side, and divides into 

 two branches. This nerve in its course between the muscles gives off muscular 

 branches to the Peroneus longus and brevis, and cutaneous filaments to the 

 integument of the lower part of the leg. 



The internal branch of the musculo-cutaneous nerve passes in front of the 

 ankle-joint and along the dorsum of the foot, supplying the inner side of the great 

 roe and the adjoining sides of the second and third toes. It also supplies the 

 integument of the inner ankle and inner side of the foot, communicating with 

 the internal saphenous nerve, and communicates with the anterior tibial nerve 

 between the great and second toes. 



The external branch, the larger, passes along the outer side of the dorsum of 

 the foot, to be distributed to the adjoining sides of the third, fourth, and fifth toes. 

 It also supplies the integument of the outer ankle and outer side of the foot, com- 

 municating with the short saphenous nerve. These dorsal digital nerves reach 

 as far as the last phalanges. 



The distribution of these branches of the musculo-cutaneous nerve will be 



55 



