796 THE NERVOUS SYSTEM. 



and the two Interosseous muscles of the fourth metatavsal space ; the other and 

 larger digital branch supplies the adjoining sides of the fourth and fifth toes, and 

 communicates with the internal plantar nerve. 



The deep or muscular branch accompanies the external plantar artery into the 

 deep part of the sole of the foot, beneath the tendons of the Flexor muscles and 

 Adductor obliquus hallucis, and supplies all the Interossei (except those in the 

 fourth metatarsal space), the three outer Lumbricales, the Adductor obliquus hal- 

 lucis, and the Adductor transversus hallucis. 



The External Popliteal or Peroneal Nerve (Fig. 423), about one-half the size of 

 the internal popliteal, descends obliquely along the outer sides of the popliteal 

 space to the head of the fibula, close to the inner margin of the Biceps muscle. It 

 is easily felt beneath the skin behind the head of the fibula at the inner side of the 

 tendon of the Biceps. It passes between the tendon of the Biceps and outer head 

 of the Gastrocnemius muscle, winds round the neck of the fibula, between the 

 Peroneus longus and the bone, and divides beneath the muscle into the anterior 

 tibial and musculo-cutaneous nerves. 



The branches of the peroneal nerve, previous to its division, are articular and 

 cutaneous. 



The articular branches are three in number ; two of these accompany the 

 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 cutaneous branches, two or three in number, supply the integument along 

 the back part and outer side of the leg ; one of these, larger than the rest, the 

 communicans 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 

 tibialis to form the external saphenous. This nerve occasionally exists as a sepa- 

 rate branch, Avhich is continued as far down as the heel. 



The Anterior Tibial Nerve (Fig. 419) commences at the bifurcation of the pero- 

 neal 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 gets into relation with the anterior tibial artery 

 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 enlarged, 

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

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

 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 

 interosseous 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. 419) supplies the muscles on the fibular 



