240 



THE ARTICULATIONS OF THE HORSE 



inches (ca. 5 cm.) ; here it is thin. It is continued downward to form the sub- 

 tarsal or check ligament, which unites with the deep flexor tendon about the mid- 

 dle of the metatarsus. 



There are four synovial sacs: 1. The tibio-tarsal sac lubricates the proximal 

 joint, and is much the largest and most important.^ 2. The proximal intertarsal 

 sac lines the joints formed by the tibial and fibular tarsal bones above, and the cen- 

 tral and fourth tarsals below; it communicates in front with the tibio-tarsal sac. 

 3. The distal intertarsal sac lubricates the joints formed between the central tarsal 

 and the bones below and on either side. 4. The tarso-metatarsal sac lubricates 



Tuber colds 



Medial malleolus -' 



Long ynedial ligament 

 Trochlea of tibial tarsal bone 



Dorsal ligament 



Mt. Ill - 



— Plantar ligament 



Mt. II 



Fig. 252. — Right Hock Joint of Horse; Medial View. The Capsule is Removed. 



1, 2, Branches of short part of medial ligament; 3, tarso-metatarsal Hgament; 4, proximal tuberosity of tibial tarsal 



bone; 5, sustentaculum; 6, groove for deep flexor tendon; Mt. XI, Mt. Ill, metatarsal bones. 



the joints formed between the tarsal and metatarsal bones, those between the 

 proximal ends of the metatarsal bones, and those formed by the third tarsal with 

 the bones on either side. 



Common Ligaments. — The lateral ligament (Lig. collaterale fibulare) consists 

 of two distinct bands which cross each other. The long lateral ligament (Lig. 

 collaterale laterale longum) is superficial ; it arises on the posterior part of the lateral 

 malleolus, is directed almost straight downward, and is attached to the fibular and 

 fourth tarsal bones and the large and lateral small metatarsal bones. It forms a 

 canal for the lateral extensor tendon. The short lateral ligament (Lig. collaterale 



^ It is this part of the capsule which is chiefly involved in distention by excess of fluid in the 

 joint cavity (as in "bog-spavin"). 



