1344 



HUMAN ANATOMY. 



bb. The internal calcanean nerve (rr. calcanei mediales) arises from the posterior tibial at 

 the lower part of the leg and becomes superficial by traversing an opening in the internal 

 annular ligament. Dividing into two sets of twigs, internal calcanean and calcaneo-plantar, it is 

 distributed to the integument of the internal aspect of the heel and posterior portion of the sole. 



cc. The articular branches are two tiny twigs, given off beneath the internal annular 

 ligament, which supply the ankle joint. 



dd. The internal plantar nerve (n. plantaris medialis) (Fig. 1121), larger than the external, 

 resembles in its distribution the median nerve in the hand. From the point of division of the 

 posterior tibial nerve it courses forward in the foot in company with the internal plantar artery, 

 lying first above the internal annular ligament and the calcanean head of the abductor hallucis 

 and then between the abductor hallucis and the flexor brevis digitorum. Passing thence for- 

 ward between the flexor brevis hallucis and the flexor brevis digitorum it divides into two ter- 



Calcaneo-plantar 

 cutaneous br. of tibial nerve 



Articular br. (usually a br. 

 of tibial nerve) 



Br. to abductor hallucis 



Int. plantar nerve 

 Brs. to flex, brevis digitorum 



I. and Il.Unnbricales 



Digital brs. of int. plantar 



Fig. 



1121. 



^ 



V 



Flexor brevis digitorum 

 Ext. plantar nerve 



Br. to abductor minimi digit! 



Abductor minimi digiti 



Flexor accessorius 



Br. to flex, accessorius 



Superficial br. ext. plantar nerve 



Brs. to flex. brev. minimi digiti 



Deep br. ext. plantar nerve 

 Digital branch 



Brs. to interossei of fourth space 

 Digital branch 



III. and IV. lumbricales 



^ -/J 



Dissection of right foot, showing internal aud external plantar nerves and their branches. 



minal branches, an inner and an outer. In addition to the terminal branches it gives off certain 

 collateral twigs. 



The collateral branches are muscular, cutaneous and articular in distribution. The 

 muscular supply the abductor hallucis and the flexor brevis digitorum. The cutaneous pass 

 between the muscles just mentioned to be distributed to the integument of the inner portion of 

 the sole. The articular furnish innervation to the inner tarsal and tarso-metatarsal joints. 



The terminal branches are an inner or mesial and an outer or lateral. 



The inner or mesial terminal branch (Fig. 1 121 ) courses forward upon the under surface of 

 the abductor hallucis, pierces the plantar fascia posterior to the tarso-metatarsal articulation oi 

 the great toe and terminates by extending along the mesial side of that toe as its inner plantar 

 digital nerve. In its course it furnishes filaments to the inner surface of the foot and a twig to 

 the mesial head of the flexor brevis hallucis. 



