DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 533 
slightly backwards under the gluteus maximus secundus and upper portion of biceps to 
the peroneal margin of the soleus, where, dipping between it and the peroneus longus 
below the head of the fibula, it divides into several branches. ‘The uppermost one, the 
anterior tibial, pierces the upper origin of the peroneus brevis muscle, and runs on the 
neck of the fibula in a shallow groove underneath the peroneus longus and the fibular 
origin of the extensor communis. It there subdivides, sending a twig to the knee-joint 
and to the extensor longus, a larger one outwards to the head of the tibialis anticus, 
and another to the extensor hallucis. 
The musculo-cutaneous nerve, or long branch of the above, goes down the leg deeply 
between the peroneus longus and extensor communis digitorum to the ankle-joint, 
where, just above the outer malleolus, it emerges, and is ultimately distributed to the 
dorsum of the foot. 
The internal popliteal nerve, the continuation of the largest cord, or the great ischiatic, 
leaves its neighbours at the middle of the fleshy belly of the quadratus femoris, and, 
pursuing a course backwards and downwards to the middle of the lower leg, divides 
into a number of branches on the inner or tibial side of the adductor magnus muscle. 
Thus, from the peculiar position of both the upper and lower part of the hind leg, it 
_does not traverse the popliteal space, but becomes in a manner the posterior tibial, 
almost in what appears, on cursory inspection, to be the region of the groin, which here, 
however, is wrenched upwards, and so clothed with muscles as to be with difficulty 
recognizable. As the internal popliteal reaches the sacro-peroneus muscle it sends a 
branch subdividing peripherally on the deep surface of the gastrocnemius. Another 
branch similarly divides and enters the semimembranosus &c. 
The posterior tibial nerve, of considerable size, passes downwards beneath the gastro- 
cnemius and upon the surface of the long flexors to the ankle, where its component 
parts, diverging, form the internal and external plantar nerves. The latter goes beneath 
the plantaris tendon as it reaches the sole of the foot, and sends muscular twigs to the 
abductor ossis metacarpi quinti, the abductor and flexor brevis minimi digiti. One 
branch, furthermore, goes to the outer side of the fourth digit, in company with the 
digital branch of the external plantar artery; another branch goes between the fourth 
and fifth digits, splitting into an ulnar twig to the fifth, and a radial twig to the fourth 
digit, besides twigs to the short palmar muscles and lumbrici. The former (internal 
plantar) divides into two at the proximal end of the foot, the plantar artery running 
between. One nerve, the inner one, proceeds to near the distal end of the proximal 
phalanx, there splitting into two branches, one for the hallux, the other for the tibial 
side of the second digit. The second division of the internal plantar nerve is more 
medianly situated, and at the proximal extremity of the metatarsal bones divides—one 
branch subdividing into the ulnar and radial twigs of the second and third digits, the 
other branch similarly subdividing into the radial and ulnar twigs respectively of the 
third and fourth digits. 
VOL. VIII.—PART IX. June, 1874. 4E 
