296 SKELETON OF THE HOKSB. 



ous powerful muscles for the movement of the limb. The chief 

 motor muscle of the hind-leg is united to the trochanter major. 

 Following and uniting with the femur are the two hones, the tibia 

 (fig. 154, B, T) and fibula, which are quite detached in certain 

 animals. In the horse the tibia is well developed, being a stout 

 strong bone, whilst the fibula is much reduced in size and 

 anchyloses with the tibia. The joint formed by the junction of 

 these two bones is known as the stifle-joint. In front of this 

 joint is a floating bone, the patella or knee-cap, which is attached 

 by three bands of ligament to the tibia. 



The tarsus or ankle forms the horse's hock; like the carpus 

 or knee, this is made up of several small bones. There are 

 six tarsal bones in all, known as the external and internal 

 cuneiforms, cuboid {Cu), navicular,^ astragalus (As), and cal 

 caneus (C). 



The astragalus is in front of the hock, at the top uniting with 

 the tibia. The calcaneus is behind the astragalus, and projects 

 upwards behind the tibia, forming the point of the hock ; it also 

 has an articulating surface with the tibia. Below the calcaneus 

 is the cuboid. Beneath the astragalus comes the navicular, 

 scaphoid, or large cuneiform ; the lower row consisting of the 

 internal and external cuneiforms, the latter being chiefly at the 

 back of the hock. The metatarsal or cannon-bone (Ga) is very 

 similar to that of the fore-limb. The foot is also similar in 

 structure, but the ultimate toe-bone is called the pedal bone 

 (fig. 154, B, Co/') ; and at the junction of the cannon-bone with 

 the large pastern are two floating bones behind (b, Ses), which 

 are covered by a horny growth, the ergot, upon which is attached 

 the tuft of hair called the fetloaJc. 



This completes the skeleton, whose function is for the attach- 

 ment of the muscles and for the protection of the various soft 

 inner parts of the body. 



' The navicular is alao called the scaphoid or centrale. The latter term 

 is best, as there is a scaphoid in the carpus, and the true navicular is a de- 

 tached sesamoid bone in the foot, the seat of the navicular disease. 



