THE SACRAL AND COCCYGEAL NERVES 963 



The sural nerve (n. suralis; short saphenous nerve), formed by the junction of the 

 medial sural cutaneous with the peroneal anastomotic branch, passes downward 

 near the lateral margin of the tendo calcaneus, lying close to the small saphenous 

 vein, to the interval between the lateral malleolus and the calcaneus. It runs 

 forward below the lateral malleolus, and is continued as the lateral dorsal cutaneous 

 nerve along the lateral side of the foot and little toe, communicating on the dorsum 

 of the foot with the intermediate dorsal cutaneous nerve, a branch of the superficial 

 peroneal. In the leg, its branches communicate with those of the posterior femoral 

 cutaneous. 



The medial calcaneal branches (rami calcanei mediates; internal calcaneal branches) 

 perforate the laciniate ligament, and supply the skin of the heel and medial side 

 of the sole of the foot. 



The medial plantar nerve (n. plantaris medialis; internal plantar nerve) (Fig. 833), 

 the larger of the two terminal divisions of the tibial nerve, accompanies the medial 

 plantar artery. From its origin under the laciniate ligament it passes under cover 

 of the Abductor hallucis, and, appearing between this muscle and the Flexor digi- 

 torum brevis, gives off a proper digital plantar nerve and finally divides opposite 

 the bases of the metatarsal bones into three common digital plantar nerves. 



BRANCHES. The branches of the medial plantar nerve are: (1) cutaneous, 

 (2) muscular, (3) articular, (4) a proper digital nerve to the medial side of the great 

 toe, and (5) three common digital nerves. 



The cutaneous branches pierce the plantar aponeurosis between the Abductor 

 hallucis and the Flexor digitorum brevis and are distributed to the skin of the sole 

 of the foot. 



The muscular branches supply the Abductor hallucis, the Flexor digitorum brevis, 

 the Flexor hallucis brevis, and the first Lumbricalis ; those for the Abductor hallucis 

 and Flexor digitorum brevis arise from the trunk of the nerve near its origin and 

 enter the deep surfaces of the muscles; the branch of the Flexor hallucis brevis 

 springs from the proper digital nerve to the medial side of the great toe, and that 

 for the first Lumbricalis from the first common digital nerve. 



The articular branches supply the articulations of the tarsus and metatarsus. 



The proper digital nerve of the great toe (nn. digitales plantares proprii; plantar 

 digital branches) supplies the Flexor hallucis brevis and the skin on the medial side 

 of the great toe. 



The three common digital nerves (nn. digitales plantares communes) pass between 

 the divisions of the plantar aponeurosis, and each splits into two proper digital 

 nerves those of the first common digital nerve supply the adjacent sides of the 

 great and second toes; those of the second, the adjacent sides of the second and 

 third toes; and those of the third, the adjacent sides of the third and fourth toes. 

 The third common digital nerve receives a communicating branch from the lateral 

 plantar nerve; the first gives a twig to the first Lumbricalis. Each proper digital 

 nerve gives off cutaneous and articular filaments; and opposite the last phalanx 

 sends upward a dorsal branch, which supplies the structures around the nail, 

 the continuation of the nerve being distributed to the ball of the toe. It will be 

 observed that these digital nerves are similar in their distribution to those of the 

 median nerve in the hand. 



The Lateral Plantar Nerve (n. plantaris lateralis; external plantar nerve) (Fig. 

 833) supplies the skin of the fifth toe and lateral half of the fourth, as well as most 

 of the deep muscles, its distribution being similar to that of the ulnar nerve in the 

 hand. It passes obliquely forward with the lateral plantar artery to the lateral 

 side of the foot, lying between the Flexor digitorum brevis and Quadratus planta?; 

 and, in the interval between the former muscle and the Abductor digiti quinti, 

 divides into a superficial and a deep branch. Before its division, it supplies the 

 Quadratus plant* and Abductor digiti quinti. 



