DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 571 
forwards in company with the obturator internus, the two are inserted together between 
the greater and lesser trochanters. The surface of this muscle is superficially tendinous 
at its origin. 
Obturator externus.—This covers the obturator membrane exteriorly, a few fibres 
overlapping it anteriorly. It is rather a thick fleshy muscle (0.¢), its tendon passing 
upwards and forwards to be inserted into the crown of the lesser trochanter. It drags 
the head of the femur backwards, and steadies that bone in walking-movements. 
The obturator internus (0.1) deeply covers entirely the obturator membrane ; and 
partly muscular and partly tendinous,-but greatly flattened, it passes round the ischiatic 
notch and mingles with the gemelli; although intermingled closely with these, it has a 
strong tendon, which is inserted as aforesaid. 
The three above-mentioned muscles act more or less together, and drag the upper 
end of the femur through the great trochanter upwards and inwards, thus serving as 
outward rotators of the upper leg. 
Quadratus femoris —Elongated and narrow. It has a fleshy origin from the ischium, 
just behind the gemellus inferior and to the outer side of the bone. It slants for- 
wards and downwards (Q.f), crossing the anterior portion of the obturator externus, 
and is inserted by a short but strong tendon on the outer side of the lesser trochanter, 
beneath the aforesaid muscle. 
Action. A rotator outwards and backwards of the femur. 
The tibialis anticus (fig. 15, T.a) arises from the front and upper half of the tibia. 
It forms a considerable-sized muscular belly as large as that of the extensor communis 
digitorum. Its tendon commences above the binding ligament, then runs underneath 
it, and below divides into two, whereof one tendon (7.a'), is inserted into the ento- 
cuneiform bone, widening into an aponeurosis; the other (7.a’) goes on to the dorsal 
surface of the proximal end of the metatarsal bone of the hallux. 
The extensor proprius hallucis (E.p.h)is a muscle of more than usual volume. It arises 
from the upper two thirds of the fibula and the interosseous membrane. Its rather 
strong distal tendon passes to the proximal end of the proximal phalanx of the hallux, 
there spreading out in fascia. 
Extensor longus digitorum.—This muscle arises from the external condyle and the 
outer surface of the fibula, and continues muscular (£./.d) to the ankle. It here forms 
a broad, flat, and strong tendon (#./.d*), which rather increases in breadth to below 
the tarsal bones, where it divides into four tendons, which supply the four outer digits. 
That to the second digit is given off highest; the three others divaricate about one level. 
The four tendons are inserted, like those of the manus, into the proximal end of the 
second phalanges, where they each broaden out and form a strong aponeurotic sheath. 
The extensor brevis digitorum is composed of two widely separated lips. ‘The first or 
innermost portion has origin from the dorsal surface of the astragalus and cuboid bones, 
and forms a long delicate tendon at the proximal end of the metatarsus; this goes to be 
