The skeleton provides support for muscles, protects vital organs and supports soft parts of the body. It also stores minerals, primarily calcium and phosphorus. The skeleton is divided into two parts – the appendicular and the axial. The appendicular skeleton contains the bones that form the limbs. The axial skeleton includes the bones that form the spine and head.
Horses have 205 bones in total. The three largest flat (or plate) bones in the skeletal system of a horse are the pelvic bone, femur and tibia. There are a number of other smaller flat bones that are found in the skeletal system. There are also many short bones that form joints in the limbs, such as the hock and fetlock. There are also a few irregular bones that are found in the skeleton of a horse.
There are a total of seven carpal and six tarsal bones in a horse’s skeleton. These bones are connected by ligaments and tendons that allow the equine to move at various speeds and provide support for the soft parts of the body.
The horse has eighteen pairs of ribs in its skeleton. The first eight pairs are sternal ribs and the final ten pairs are asternal ribs. These ribs attach via cartilage to the sternum and form the costal arch. The ribs of a horse are bandlike and vary in length, breadth and curvature. The ribs of a horse have a concave medial surface and a flat dorsal surface. The ribs of a horse also have a tubercle and a lateral ventral groove.
There is strong morphological integration of the axial and appendicular skeletons in horses. The occurrence of such integration in the hind limb long bones (femur and tibia) may suggest that developmental mechanisms reinforce covariation between elements involved in locomotion in equines.
Horse skeletal anatomy consists of a series of irregular, short and long bones that form the limbs, trunk and tail. There are a total of 54 vertebrae in the neck, back and limbs.
Short bones are located in the hands and feet of a horse. The phalanx of each foot has three phalanges. The proximal phalanx is known as the long pastern and the distal phalanx is called the short pastern. The phalanges of the foot are joined by a joint that is called the fetlock joint. The fetlock joint is important because it allows the limb to bend and twist.
The ulna of a horse is the most reduced long bone in its skeleton. The bone possesses a triangular shaft with a dorsolateral surface and a cranial surface. The proximal extremity of the ulna bears articular surfaces for the radius and humerus bones. The distal extremity of the ulna has a styloid process. This bone has a slender shaft with three sides and a dorsal surface that is concave. The ulna also has a groove in its ventral surface and a tubercle in its dorsal portion.