ss kl a aie a 
INTERNAL PLANTAR NERVE. 611 
tibialis, n. cutaneus sur medialis). This nerve passes from the popliteal space in 
the groove between the two heads of the gastrocnemius muscle, and afterwards lies 
upon the tendo achillis. It pierces the deep fascia in the middle third of the back 
of the leg, and is joined immediately afterwards by 
the peroneal communicating nerve from the peroneal 
nerve. From their union the external or short saphenous 
nerve results, which reaches the foot, winding round 
the back of the external malleolus along with the 
external saphenous vein. The external saphenous 
nerve supplies cutaneous branches to the outer side 
and back of the lower third of the leg, the ankle and 
heel, and the outer side of the foot and little toe, as 
well as articular branches to the ankle and _ tarsal 
joints. 
The external saphenous nerve communicates on the 
foot with the musculo-cutaneous nerve, and its size varies 
with the size of that nerve. It may extend on to the 
dorsum of the foot for a considerable distance, and may 
either reinforce or replace the branches of the musculo- 
cutaneous nerve to the intervals between the fourth and 
fifth and even the third and fourth toes. The mode of 
formation of the external saphenous nerve is very variable. 
The usual arrangement is that described. Frequently 
the peroneal and tibial communicating nerves do not unite, 
and in such cases the more usual arrangement is for the 
tibial communicating nerve to form alone the external 
saphenous nerve, the peroneal communicating nerve extend- 
ing only to the ankle and heel. It is less usual for the 
peroneal communicating nerve to form alone the external 
saphenous nerve, the tibial communicating nerve in these 
cases ending at the heel. 
4 
(c) Branches arising in the Back of the Leg below 6! aaa ay) 
the Knee-Joint.—These branches are mainly muscular 
and cutaneous. 
The muscular branches are four in number, com- jee 
prising nerves to the soleus (entering its deep surface) oi cass 
and tibialis posticus, often arising by a common trunk, i 
and nerves to the flexor longus digitorum and flexor \ } 
longus hallucis, the latter generally accompanying the Hv, Fe 
peroneal artery for some distance. \ Vy 
The cutaneous branch is the internal calcanean se F Se 
nerve (rr. calcanei mediales), which pierces the internal 
aomular licament, and! as) distribated to, the, skam, of Pc. 44. Usmmunon oy coe 
the heel and back part of the sole of the foot. 
In addition a medullary nerve to the fibula, and 
a small articular branch to the ankle-joint, are sup- 
plied by the posterior tibial nerve. 
The terminal branches of the tibial nerve are 
the internal and external plantar nerves. 
INTERNAL PLANTAR NERVE. 
The internal plantar nerve (n. plantaris medialis) 
is homologous with the median nerve in the hand (Fig. 
445, p. 612). It is rather larger than the external 
plantar. It courses forwards in the sole of the foot 
NEOUS NERVES ON THE Back OF 
THE LOWER Lip. 
On the one side the distribution of 
the several nerves is represented 
the letters indicating their nomen- 
clature. 
L.1, 2, 3, 8.1, 2, 3, Posterior primary 
divisions of lumbar and_ sacral 
nerves; I.H, Ilio-hypogastric; T.12, 
Lateral and posterior branches of 
last thoracic nerve; A.Co!, Posterior 
sacro-coccygeal nerve ; A.Co?, An- 
terior sacro-coccygeal nerve ; PERF, 
Perforating cutaneous nerve ; S.Se, 
Small sciatic ; B.C, External cuta- 
neous; Ost, Obturator ; I.C, In- 
ternal cutaneous; E.P.S, Sural 
branches of peroneal ; I.S, Internal 
saphenous ; E.S, External saphenous ; M.C, Musculo-cutaneous ; Cac, Caleanean branch of posterior 
’ 3 
tibial ; I.P, Internal plantar ; E.P, External plantar nerve. 
On the other side a schematic representation is given of the areas supplied by the aboye nerves, the letters 
indicating the spinal origin of the branches of distribution to each area. 
7 2 ‘ 
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