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 to 4 cm.) 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 laj'er of the medial ligament of the hock, and is 

 provided with a bursa. 



The peroneus longus descends in front of the fibula and 

 the lateral extensor. It arises chiefly from the lateral con- 

 dyle of the tibia. The tendon of insertion descends through 

 a groove on the lateral malleolus, crosses over the tendons 

 of the lateral extensor, then under the lateral ligament to 

 the plantar surface of the hock, to end on the first tarsal 

 bone. There is a bursa under the tendon where it lies in 

 the groove on the fourth tarsal. The muscle is a flexor of 

 the hock. 



The long digital extensor arises in common with the 

 peroneus tertius, by which it is largely covered and with 

 which it is united to the distal third of the leg. Three ten- 

 dons appear at the proximal annular ligament and extend 

 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 

 (third and fourth) digits. This tendon is joined before bifurcating by the tendon 

 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 from the inter- 



FlG. 318. — Muscles of Leg 

 AxD Foot of Fig; Dohso- 

 LATEHAL View. 

 a, Tibialis anterior; a', 

 tendon of preceding; b, pero- 

 neus tertius; b', tendon of b; 

 c, long digital extensor; d, e, f, 

 /', /", tendons of c; g, peroneus 

 longus; p', tendon of g; h, 

 extensor digiti quarti; h', 

 tendon of h, which receives h" 

 from the interosseus medius; 

 I, extensor digiti quinti; A-, deep 

 digital fiexor; I, soleus; m, 

 gastrocnemius; n, extensor dig- 

 italis brevis. (.\fter EUenber- 

 ger, in Leisering's Atlas.) 



