APPENDICULAR SKELETON. 65 



culum, while the posterior extremity presents a kind of thickened 

 elbow or curve inferiorl}^, and terminates superiorly in a rounded 

 extremity, which is united to the temporal bone by a piece of 

 fibro-cartilage. Among mammals the hyoid cornua attain per- 

 haps in the horse the maximum of relative size. Occasionally a 

 rudimentary additional ossicle is found in the cartilage between 

 the cornu and corniculum. 



Various muscles connect the hyoid bones with the tongue, 

 larynx, and pharynx. It may be noted here that both the ali- 

 mentary and respiratory canals pass between the hyoid cornua. 



APPENDICULAR SKELETON. 



This division of the skeleton includes the bones which belong 

 to the limbs or extremities, and those which help to join the 

 latter to the trunk, when such bony union exists. The horse, 

 like the majority of mammals, has two pairs of limbs — an 

 anterior, fore, thoracic, or pectoral, and a posterior, hind, or pelvic 

 pair, which have bones of connection, called respectively the 

 pectoral and pelvic arches. In the horse, as in many other 

 animals, there is no articular connection between the anterior 

 limb and the trunk, hence the 'pectoral arch is incomplete. The 

 actual attachment of this limb is entirely muscular, the body 

 being suspended, as it were, in a muscular sling between the 

 anterior limbs. 



There is a certain correspondence between the bones of the 

 fore and those of the hind limb, as reference to the skeleton and 

 the following Table will show : — 



Pectoral Limb. Pelvic Limb. 



Humerus. .... Femur. 



(Olecranon). . . . Patella. 



Radius and Ulna. . . Tibia and Fibula. 



Carpus (8 bones). . . Tarsus (6 bones). 



Metacarpus (3 bones). . . Metatarsus (3 bones). 



Phalanges, 3. . . . Phalanges, 3. 



Sesamoids, 3. . . . Sesamoids, 3. 



The humerus and femur, when the animal is stationary, slope 

 in opposite directions, and the two pairs of bones beneath them 

 appear to do the same ; it is probable, however, that the axis of 

 the radius itself is as nearly perpendicular as possible. 



F 



