954 THE NERVOUS SYSTEM 



The recurrent articular nerve passes inwards, around the neck of the fibula, 

 and through the upper part of the origin of the extensor digitorum longus. At 

 the inner border of the fibula it becomes associated with the anterior tibial 

 recurrent artery, with which it ascends through the upper part of the tibialis 

 anterior to the head of the tibia and the knee-joint. It supplies the tibialis anterior, 

 the superior tibio-fibular joint, and the knee-joint. 



The terminal branches. The superficial peroneal (musculo-cutaneous) 

 nerve arises from the common peroneal between the peroneus longus and the neck 

 of the fibula and descends in the intermuscular septum between the long and short 

 peronei on the outer side, and the extensor digitorum longus on the inner side. It 

 gives off muscular and cutaneous branches in its descent, and at the junction of the 

 middle and lower thirds of the leg it pierces the deep fascia and divides into an 

 internal and an external branch (fig. 697). 



Branches. Muscular branches are given off to the peroneus longus and 

 peroneus brevis before the nerve pierces the deep fascia. 



Cutaneous branches pass from the trunk of the nerve to the skin of the lower 

 part of the front of the leg. 



The internal cruciate branch, the medial dorsal cutaneous, passes downwards 

 and inwards across the upper and lower bands of the dorsal digital (anterior annular) 

 ligament of the ankle and subdivides into two branches. The inner branch passes to 

 the inner side of the great toe; it also supplies twigs to the skin of the inner side of the 

 foot, and it anastomoses with the deep saphenous nerve and with the internal ter- 

 minal branch of the deep peroneal (anterior tibial) nerve. The outer branch passes 

 to the base of the cleft between the second and third toes and divides into two 

 dorsal digital branches which supply the adjacent sides of the cleft. 



The external branch (intermediate dorsal cutaneous), in separating from 

 the internal branch, crosses in front of the upper and lower bands of the cruciate 

 ligament and divides into two dorsal digital branches, which pass beneath the dorsal 

 venous arch. The inner of these branches supplies the adjacent sides of the third 

 and fourth toes (fig. 697). The outer branch communicates with the sural (external 

 saphenous) nerve and is distributed to the adjacent sides of the fourth and fifth 

 toes. This latter branch is frequently replaced by the sural nerve. 



The deep peroneal (anterior tibial) nerve springs from the end of the common 

 peroneal (external popliteal) nerve between the peroneus longus muscle and the neck 

 of the fibula. It passes forwards and inwards through the upper part of the origin of 

 the extensor digitorum longus, to the interval between that muscle and the tibialis 

 anterior; then it descends, in the anterior compartment of the leg, to the ankle, 

 where it divides into an inner and an outer terminal branch (fig. 697) . In the upper 

 part of the leg the nerve lies between the extensor digitorum longus and tibialis 

 anterior and to the outer side of the anterior tibial artery. In the middle of the leg 

 it is in front of the artery and between the extensor hallucis longus and tibialis an- 

 terior; then it crosses beneath the extensor hallucis, and in the lower third of the leg 

 it is again to the outer side of the artery, but between the extensor hallucis longus and 

 the extensor digitorum longus. 



Branches furnished from the trunk of the nerve are muscular, articular, and 

 terminal. 



The muscular branches supply the tibialis anterior, extensor digitorum longus, 

 extensor hallucis longus, and peroneus tertius. 



Articular filaments are given to the ankle-joint and the inferior tibio-fibular 

 articulation. 



Terminal branches. The inner terminal branch passes downwards along the 

 side of the dorsalis pedis artery and divides into two dorsal digital branches which 

 supply the adjacent sides of the first and second toes. It also gives filaments to the 

 periosteum of the adjacent bones, to the metatarso-phalangeal and interphalangeal 

 articulations, a twig to the dorsal interosseous muscle of the first space, and a per- 

 forating twig which communicates with the lateral plantar nerve. 



The outer terminal branch passes outwards, beneath the extensor digitorum 

 brevis, and it ends in a gangliform enlargement from which branches are distributed 

 to the extensor digitorum brevis, the tarsal joints, and to the three outer inter- 

 metatarsal spaces. The latter branches supply the neighbouring bones, periosteum, 

 and joints. They give off perforating twigs, which pass through the spaces and 

 anastomose with branches of the lateral plantar nerve, and the innermost also gives 

 a twig to the second dorsal interosseous muscle. 



