SOLE OF THE FOOT. 247 



The internal plantar nerve is the larger of the two, and runs along 

 the edge of the abductor pollicis muscle, and divides opposite the 

 bases of the metatarsal bones, into four digital branches which sup- 

 ply, by bifurcating, both sides of the first, second, and third toes, and 

 the inside of the fourth toe ; it also gives off small muscular branches. 



The external plantar nerve accompanies the external plantar artery 

 as far as the fifth metatarsal space, where it sends off a large muscu- 

 lar branch, and continues on in two divisions, which supply the outer 

 edge of the foot, the little toe, and the outside of the next, which is un- 

 supplied by the internal plantar. 



In the second layer of muscles are found the tendons of 

 the flexor longus digitorum and flexor longus pollicis mus- 

 cles, the bellies of which have been already dissected upon 

 the back of the leg (p. 243). The tendon of the flexor 

 longus digitorum passes to the middle of the sole of the 

 foot, and is there joined by a tendinous process from the 

 flexor longus pollicis, and by the musculus accessorius; it 

 then divides into four tendons for the outer four toes ; these 

 perforate the tendons of the flexor brevis, and are held 

 down to the phalanges by ligamenta brevia, like those of 

 the tendons of the fingers (p. 154). Their insertion and that 

 of the flexor longus pollicis have previously been given. 



The LUMBRICALES MUSCLES are four small muscles arising 

 from the tendons of the long flexor, and inserted into the 

 expansions of the extensor tendons, and the inner sides of 

 the first phalang-es of all the toes except the great toe. 

 They are subject to variations. 



The MUSCULUS ACCESSORIUS, or MASSA CARNEA JACOBI 

 SYLVII, arises by two heads, one from the concave, inner 

 side of the os calcis, and the other from its under surface, 

 and is inserted into the tendon of the flexor longus digi- 

 torum, just as it breaks up into its four digital divisions. 



The tendons of the flexor longus must be divided, and, with their 

 accessory muscles, reflected. 



The FLEXOR BREVIS POLLICIS PEDIS arises from the 

 cuboid and external cuneiform bones ; it lies upon the me- 

 tatarsal bone of the great toe, and is inserted by two heads 

 into the base of its first phalanx ; the outer head joins with 

 the tendon of the abductor pollicis, and the inner head with 

 that of the adductor pollicis ; a sesamoid bone is usually 

 found in each of these heads ; the tendon of the flexor 

 longus pollicis passes between them. 



The ADDUCTOR POLLICIS PEDIS is placed obliquely in the 

 sole of the foot ; it arises from the cuboid bone, the bases 



