366 THE MUSCLES OF THE PIG 
MUSCLES OF THE LEG AND FOOT 
The peroneus tertius is a well-developed muscle which is in great part super- 
ficially situated on the front of the leg. It covers the long digital extensor, with 
which it is united except in the distal third of the leg. It arises from the extensor 
fossa of the femur by a common tendon with that muscle, 
a synovial pouch from the femoro-tibial joint extending 
down under the origin. 
This sac is an inch and a half or more (ca. 3 to4em.) in length 
in large subjects and extends around the lateral edge of the tendon 
to its superficial face, so as to make a partial sheath and underlie 
the origin of the peroneus longus also. 
The muscle is continued at the distal end of the leg 
by a strong tendon which passes over the flexion surface of 
the hock, between the tendon of the long extensor (lateral) 
and that of the tibialis anterior (medial), all three being 
bound down by a strong annular ligament which extends 
across from one malleolus to the other. It ends by two 
or more branches on the first and second tarsal and third 
metatarsal bones. Not rarely there is a thin tendon in- 
serted into the fourth metatarsal bone. The tendon usu- 
ally receives a small branch from that of the tibialis an- 
terior at the annular ligament. 
The tibialis anterior is smaller than the preceding. It 
arises from the lateral surface of the tuberosity and lateral 
condyle of the tibia. At the distal end of the leg the ten- 
don passes under the annular ligament mentioned above 
(where it detaches a small branch to the peroneus tertius), 
and ends on the second tarsal and the proximal end of the 
second metatarsal bone. The terminal part passes under a 
superficial layer of the medial ligamentof the hock, andis 
provided with a bursa. 
The peroneus longus descends in front of the fibula and 
Fic. 318—Muscies or Lea the lateral extensor. It arises chiefly from the lateral con- 
axp Foor or Pra; Dorso- dye of the tibia. The tendon of insertion descends through 
Seen wee a groove on the lateral malleolus, crosses over the tendons 
tendon of preceding; b, pero- Of the lateral extensor, then under the lateral ligament to 
neus tertius; b’, tendon of b; the plantar surface of the hock, to end on the first tarsal 
ey ett ep Gene bone. There is a bursa under the tendon where it lies in 
longus; g’, tendon of g; h, the groove on the fourth tarsal. The muscle is a flexor of | 
extensor digiti quarti; tds the hock. | 
es Ae ee, The long digital extensor arises in common with the | 
i, extensor digiti quinti; k,deep  peroneus tertius, by which it is largely covered and with 
digital Hexors fy soleusi ™ which it is united to the distal third of the leg. Three tem 
falls broviee "(Atter Elleubee ONS appear at the proximal annular ligament and extend 
ger, in Leisering's Atlas.) downward and a little medially over the flexion surface of 
the hock. Here they are bound down by an annular liga- 
ment given off from the tendon of the peroneus tertius and attached laterally 
to the distal end of the fibular tarsal bone. The tendons gradually diverge as | 
they descend the metatarsus. The central one divides at the distal end of the | 
metatarsus into two branches which end on the third phalanges of the chief | 
a, Tibialis anterior; a’, 
(third and fourth) digits. This tendon is joined before bifurecating by the tendon |" 
x we . | 
of the extensor digitalis brevis. The medial tendon ends on the second and third | 
phalanges of the medial chief (third) digit. It receives a branch fron the inter- 
