PLANTAR NERVES. 619 



The PLANTAR NERVES (fig. 210) are derived from the bifurcation of 

 the posterior tibial trunk behind the inner ankle. They are two in num- 

 ber, like the arteries, and have the same anatomy as those vessels, for 

 each accompanies a plantar artery; but the larger nerve lies with the 

 smaller bloodvessel. 



The internal plantar nerve ( J ) courses between the short flexor of the 

 toes and the abductor pollicis, and giving but few muscular offsets, divides 

 into four digital branches ( 2 , 3 , *, 5 ) for the supply of both sides of the inner 

 three toes, and half the fourth ; it resembles thus the median nerve of the 

 hand in the distribution of its branches. 



Muscular offsets are given by it to the short flexor of the toes (perfo- 

 ratus) and the abductor pollicis; and a few superficial twigs perforate the 

 fascia. 



The four digital nerves have a numerical designation, and the first is 

 nearest th-j inner border of the foot. The branch ( 2 ) to the inner side of 

 the great toe is undivided, but the others are bifurcated at the cleft be- 

 tween the toes. 



Muscular branches are furnished by these nerves before they reach the 

 toes ; thus, the first (most internal) supplies the flexor brevis pollicis ; the 

 second gives a branch to the inner lumbrical muscle, and the third, to the 

 next lumbricalis. 



Digital nerves on the toes. Each of the outer three nerves, being 

 divided at the spot mentioned, supplies the contiguous sides of two toes, 

 whilst the first belongs alone to the inner side of the great toe ; all give 

 offsets to the teguments, and the cutis beneath the nail, and articular fila- 

 ments are distributed to the joints as in the fingers. 



The external plantar nerve ( 6 ) is spent chiefly in the deep muscles of 

 the sole of the foot, but it furnishes digital nerves to both sides of the little 

 toe, and the outer side of the next. It corresponds in its distribution with 

 the ulnar nerve in the hand. 



It has the same course as the external plantar artery, and divides at the 

 outer margin of the flexor brevis digitorum into a superficial and a deep 

 portion: the former gives origin to two digital nerves; but the latter 

 accompanies the arch of the plantar artery into the foot, and will be dis- 

 sected afterwards. 



Whilst the external plantar nerve is concealed by the short flexor of 

 the toes, it gives muscular branches to the abductor minimi digiti and the 

 flexor accessorius. 



The digital branches of the external plantar nerve ( 7 , 8 ) are two. One 

 ( 7 ) is undivided ; it is distributed to the outer side of the little toe, and 

 gives offsets to the flexor brevis minimi digiti, and oftentimes to the inter- 

 osseous muscles of the fourth space. The other ( 8 ) bifurcates at the cleft 

 between the outer two toes, and supplies their collateral surfaces : this 

 nerve communicates in the foot with the last digital branch of the internal 

 plantar nerve. 



On the sides of the toes the digital nerves have the same distribution 

 as those from the other plantar trunk, and end like them in a tuft of fine 

 branches at the extremity of the digit. 



Dissection (fig. 211). To complete the preparation of the second layer 

 of muscles, the origin of the abductor pollicis should be detached from the 

 os calcis, and the muscle should be turned inwards. The internal plantar 

 nerve and artery, and the superficial portion of the external plantar nerve, 

 are to be cut across and thrown forwards ; but the external plantar artery 



