THE FOOT. 



FIG. 88. A frontal section of the talocrural and talocalcaneal articulations. 

 FIG. 89. A diagrammatic representation of the joints of the foot. 



tar sea later alls], passing beneath the extensor brevis digitorum and anastomosing with the next 

 branch, the metatarsal artery (A. arcuata), which runs outward upon the bases of the metatarsal 

 bones and gives off the dorsal metatarsal arteries for the second, third, and fourth metatarsal 

 spaces and the corresponding sides of the toes. To the inner side, the dorsalis pedis gives off 

 two or three insignificant vessels, the A a. tarsece mediales. 



The nerves of the dorsum of the foot (Fig. 85) are: (i) The musculocutaneous, which divides 

 at a higher level into an external and an internal branch (see page 167). They supply digital 

 branches for all of the toes except the outer side of the little toe and the adjacent surfaces of 

 the great and second toes. The latter is supplied by the anterior tibial; the outer margin of 

 the dorsum of the foot and of the little toe is supplied by the short saphenous, which is known 

 in this situation as the N. cutaneus dorsi pedis lateralis. All three nerves inosculate with each 

 other. 



Sole of the Foot. Beneath the tough skin of the sole of the foot there is a thick cushion 

 of fat which is particularly well developed posteriorly. Beneath this fat is the strong plantar 

 fascia, which, like the palmar fascia, gives off five processes for the sheaths of the flexor tendons 

 and the skin and possesses transverse trabeculae. In the middle of the foot the fascia is con- 

 siderably thicker than at the sides and covers the flexor brevis digitorum muscle, furnishing an 

 origin for some of its fibers. The external plantar artery (see page 167 and Fig. 87) passes into 

 the sole beneath the abductor hallucis and then runs outward between the flexor brevis digitorum 

 and the flexor accessorius; the vessel then curves to the inner side of the foot and forms the 

 plantar arch by anastomosing with the communicating branch of the dorsalis pedis. The plantar 

 arch lies directly upon the bases of the second, third, and fourth metatarsal bones and upon the 

 interosseous muscles. Anteriorly it gives off four digital branches (Aa. metatarsece plantares} 

 for the interosseous spaces and the corresponding sides of the toes, while the outer and inner 

 margins of the sole are supplied by separate branches from the arch. The smaller internal 

 plantar artery runs anteriorly to the inner side of the abductor hallucis to the great toe, where 

 it usually anastomoses with the first digital branch (.4. metatarsa plantaris I). 



Before entering the sole the posterior tibial nerve divides into the external and the internal 

 plantar nerves. The external plantar nerve accompanies the external plantar artery and divides 

 into a superficial and a deep branch (Fig. 87). The superficial branch supplies the muscles of 

 the ball of the little toe and gives off three digital nerves to the sides of the little toe and to the 

 outer side of the fourth toe. The deep branch follows the plantar arch into the depth of the 

 sole and supplies the interosseous muscles and the adductor hallucis. The internal plantar 

 nerve runs to the inner side of the flexor brevis digitorum, supplies the muscles of the ball of 

 the great toe and the flexor brevis digitorum, and ends in seven digital nerves which supply 

 both sides of the three inner toes and the inner side of the fourth toe. 



For the movements of the foot there are two joints which are worthy of particular atten- 

 tion: 



i. The ankle-joint, or talocrural articulation (Figs. 88 and 89), between the leg and the 



