PLANTAR VESSELS AND NERVES. 617 



tubercle, and from the plantar fascia and the external intermuscular sep- 

 tum. It ends anteriorly in a tendon which is inserted into the outer side 

 of the base of the metatarsal phalanx of the little toe. 



The muscle lies along the outer border of the foot, and conceals the 

 flexor accessorius, and the tendon of the peroneus longus. On its inner 

 side are the external plantar vessels and nerve. Sometimes a part of the 

 muscle is fixed into the projection of the fifth metatarsal bone. 



Action. Though it abducts the little toe from the others, as the name 

 signifies, its chief use is to bend the metatarso-phalangeal joint. 



Dissection. To bring into view the second layer or muscles and the 

 plantar vessels and nerves, the muscles already examined must be re- 

 flected. Cut through the flexor brevis at the os calcis, and as it is raised, 

 notice a branch of nerve and artery to it. Dividing the abductor minimi 

 digiti near its origin, and turning it to the outer side of the foot, seek its 

 nerve and vessel close to the calcaneum. The abductor pollicis can be 

 drawn aside if it is necessary, but it may remain uncut till afterwards. 



Next the internal plantar vessels and nerve are to be followed forwards 

 to their termination, and backwards to their origin ; and the external 

 plantar vessels and nerve, the tendons of the long flexors of the toes, the 

 accessory muscle, and the small lumbricales, should be freed from fat. 



The PLANTAR ARTERIES (fig. 210) are the terminal branches of the 

 posterior .tibial trunk, and supply digital offsets to the toes. They are 

 two in number, and are named external and internal from their rela- 

 tive position in the sole of the foot. Of the two the external is the 

 larger, and forms the plantar arch of arteries. 



The internal artery (b) is inconsiderable in size, and accompanies the 

 internal plantar nerve, under cover of the abductor pollicis, as far as the 

 middle of the foot, where it ends in four superficial digital branches. (Il- 

 lustrations of Dissections, p. 404.) 



Branches. The artery furnishes muscular branches, like the nerve, to 

 the abductor pollicis and flexor digitorum perforatus, and to the flexor 

 brevis pollicis and the two internal lumbricales. Its superficial digital 

 branches accompany the digital nerves of the internal plantar, and are 

 thus disposed of: 



The first is distributed to the inner side of the foot and great toe; the 

 second lies over the first interosseous space; the third corresponds with 

 the second space; and the fourth is placed over the third space. At the 

 root of the toes the last three join the deeper digital arteries in those 

 spaces. 



The external artery (a) takes an arched course in the foot, with the 

 concavity of the arch turned inwards. The vessel is first directed out- 

 wards across the sole, and then obliquely inwards towards the root of the 

 great toe, so that it crosses the foot twice. In the first half of its extent, 

 viz., from the inner side of the calcaneum to the base of the metatarsal 

 bone of the little toe, the artery is comparatively superficial; in the other 

 half, between the. little and the great toe, it lies cleeply in the foot, and 

 forms the plantar arch. 



Only the first part of the artery is now laid bare ; the remaining part, 

 supplying the digital branches, will be noticed after the examination of 

 the third layer of muscles (p. 623). 



As far as the metatarsal bone of the little toe, the vessel is concealed by 

 the abductor pollicis and the flexor brevis digitorum ; but for a short dis- 

 tance near its termination it lies in the interval between the last muscle 



