THE NERVES. 421 



tceus, the muscles of the calf, m. tibialis postic. and flexor hattucis 

 longus. Farther : 



1 . N. communicans tibialis s. cutaneus longus (s. saphenus ex- 

 ternus), descends behind the popliteal space and the calf, then 

 curves under the external malkolus and unites with n. com- 

 munic. flbularis, as : 



N. dorsalis extern, digiti 5, on the outer border of the foot 

 and to the fifth toe (see before). 



2. jZV. cutaneus plantaris arises in the centre of the leg, per- 

 forates the fascia on the tendo Achillis, and passes to the skin 

 of the heel and the sole. 



3. N. plantaris internus, arises under proc. internus calcanei, 

 passes over m. abductor hallucis, and between this and flex, 

 digit, commun. brevis, and bifurcates. Its internal smaller 

 branch passes on the inner border of the sole to the great toe, 

 supplying the skin and mm. flexor and abductor brevis. Its 

 external branch bifurcates, supplies the skin, mm. lumbricales 

 [only two] and interossei [?] and the joints, as well as the 

 collateral plantar surfaces of the first and second, the second 

 and third, the third and fourth toes. 



4. N. plantaris externus, is stronger, passes forwards between 

 caro quadrata and flexor, digitor. comm. brevis to the outer 

 border of the foot, gives branches to these muscles, and ab- 

 duct, brevis digit. 5. Its superficial branch supplies the col- 

 lateral surfaces of the fourth and fifth, and the outer surface 

 of the fifth toe. Its deeper branch passes in a curve to the 

 arcusarter. plantaris, inwards and forwards, and supplies the 

 adductor halluc.flex. digiti 5, and interossei. 



668. V. The Coccygeal Nerves, Nervi coccygei, 

 (one or two pairs), 



arise from the conus medullaris with a single root which descends 

 in thefllium terminale, enlarges at the point of the sheath of dura 

 mater, passes out and descends with two branches on the middle 

 ligament of the sheath to the inferior extremity of the sacrum. 

 The anterior branch is the larger, passes out between the cornu 

 and the superior part of the first piece of the coccyx, forwards, 

 unites with n. sympathicus (see ganglion coccygeum) ; and with 

 the anterior branch of the fifth sacral nerve. 



The posterior branch passes immediately backwards, and unites 

 with the posterior branch of the fifth sacral nerve. 



