THE PLANTAR NERVES. 



795 



Internal 

 plantar.' 



External 

 plantar. 



accompanying the peroneal artery. The branch to the Soleus enters its deep 

 surface, while the branch which this muscle receives from the internal popliteal 

 enters its superficial aspect. 



The calcaneo-plantar (internal calcaneari) branch perforates the internal 

 annular ligament, and supplies the integument of the heel and inner side of the 

 sole of the foot. 



The articular branch is given off just above the bifurcation of the nerve and 

 supplies the ankle-joint. 



The Internal Plantar Nerve (Fig. 424), the larger of the two terminal branches 

 of the posterior tibial, accompanies the internal plantar artery along the inner side 

 of the foot. From its origin at the inner ankle it passes beneath the Abductor 

 hallucis, and then forward between this muscle and the Flexor brevis digitorum, 

 divides opposite the bases of the metatarsal bones into four digital branches, and 

 communicates with the external plantar nerve. 



Branches. In its course the internal plantar nerve gives off cutaneous 

 branches, which pierce the plantar fascia and supply the integument of the sole 

 of the foot ; muscular branches, which supply the Abductor hallucis and Flexor 

 brevis digitorum ; articular branches, to the articulations of the tarsus and meta- 

 tarsus ; and four digital branches. The 

 three outer branches pass between the divis- 

 ions of the plantar fascia in the clefts be- 

 tween the toes : the first (innermost) branch 

 becomes cutaneous farther back between the 

 Adductor hallucis and Flexor brevis digi- 

 torum. They are distributed in the following 

 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 ; l the third 

 digital branch supplies the adjacent sides of 

 the second and third toes; the fourth sup- 

 plies the corresponding sides of the third and 

 fourth toes, and receives a communicating 

 branch from the external plantar nerve. 

 Each digital nerve gives off cutaneous and 

 articular filaments ; and opposite the last 

 phalanx sends a dorsal branch, which sup- 

 plies the structures around the nail, the con- 

 tinuation of the nerve being distributed to 

 the ball of the toe. It will be observed that 

 the distribution of these branches is precisely 

 similar to that of the median nerve in the 

 hand. 



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 ex- 

 ternal plantar artery to the outer side of the foot, lying between the Flexor brevis 

 digitorum and Flexor accessorius, and in the interval between the former muscle 

 and Abductor minimi digiti divides into a superficial and a deep branch. Before 

 its division it supplies 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, 



1 See foot-note, page 448. 



Deep 

 branch. 



FIG. 424. The plantar nerves. 



