864 



THE NERVOUS SYSTEM. 



Internal 

 plantar. 



External 

 plantar. 



Deep 

 branch. 



tarsus ; and four digital branches. These pass between the divisions of the 

 plantar fascia in the clefts between the toes, and are distributed in the fol- 

 lowing manner: The first supplies the inner border of the great toe, and 

 sends a filament to the Flexor brevis hallucis muscle ; the second bifurcates 

 to supply the adjacent sides of the great and second toes, sending a filament 

 to the First lumbrical muscle; the third digital branch supplies the adjacent 

 sides of the second and third toes, and the Second lumbrical muscle ; the 



fourth supplies the corresponding sides of 

 the third and fourth toes, and receives a 

 communicating branch from the external 

 plantar nerve. It will be observed that 

 the distribution of these branches is pre- 

 cisely similar to that of the median nerve 

 in the hand. Each digital nerve gives off 

 cutaneous and articular filaments, and oppo- 

 site the last phalanx sends a dorsal branch, 

 which supplies the structure round the nail, 

 the continuation of the nerve being dis- 

 tributed to the ball of the toe. 



The external plantar nerve, the smaller 

 of the two, completes the nervous supply to 

 the structures of the sole of the foot, being 

 distributed to the little toe and one-half 

 of the fourth, as well as to most of the 

 deep muscles, its distribution being similar 

 to that of the ulnar in the hand. It passes 

 obliquely forward with the external plantar 

 artery to the outer side of the foot, lying 

 between the Flexor brevis digitorum and 

 Flexor accessorius, and in the interval be- 

 tween the former muscle and Abductor 

 minimi digiti divides into a superficial and 

 a deep branch. Before its division it sup- 

 plies the Flexor accessorius and Abductor 

 minimi digiti. 



The superficial branch separates into 

 two digital nerves : one, the smaller of 



the two, supplies the outer side of the little toe, the Flexor brevis minimi digiti, 

 and the two Interosseous muscles of the fourth metatarsal 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 transversus hallucis, and supplies all the Interossei (except those in the 

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

 lucis, and the Adductor transversus hallucis. 



The External Popliteal or Peroneal Nerve (Fig. 510), about one-half the size cf 

 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, pierces the 

 origin of the Peroneus longus, and divides beneath that 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 



FIG. 511. The plantar nerves. 



