There are many bones in a horse’s body. Some are flat, such as the collar bone (scapula) and the clavicle. Others are long, such as the sternum, backbones and ribs. Bones are held together by ligaments and tendons, which connect muscle to bone. A horse’s skeleton is also surrounded by a layer of connective tissue called synovial fluid, which lubricates movement between bones.
The most important muscles in a horse are the large ones that power its limbs to carry its weight and provide propelling force. This is why horses are so much faster than any other land mammal.
In order to achieve such speed, the horse’s limbs have been modified. They have evolved from three to four-toed, dog-like feet to the single digit that is encased in the hoof of a modern horse. This enables the horse to keep its center of gravity low, which helps it maneuver and turn quickly.
A horse is a prey animal and during its evolution it has developed to be able to move quickly away from predators. As a result, the legs have been developed to be very strong and well-shaped for support and shock absorption. The front legs have the additional support of the rib cage, while the hind legs are more angled for propelling force.
While the skeletal structure of a horse is strong, it can still be injured. The tendons and ligaments that connect muscles to the bones are especially vulnerable. Injuries to these tissues can cause pain and reduce the efficiency of the limbs.
When a bone is stressed, it may lose some of its mineral density. This is a normal part of the process, but when repeated over time, it can be a problem. Bone loss can lead to a reduction in the strength of the bones, which increases the likelihood that they will break under stress.
To understand the relationship between stress and osteoporosis, researchers have studied how horses react to exercise. They have found that when a horse runs, its distal leg bones experience long periods of loading and short periods of rest. This causes microcracking, which may increase the risk of osteoporosis.
The bones of a horse’s lower leg are joined to the foot by a complex arrangement. The coffin joint lies between the short pastern and the pedal bone, and includes the proximal and distal sesamoids. The proximal sesamoids are known as “sesamoid bones” and the distal one is commonly called the navicular bone. The function of these bones is to act like pulleys for the tendons that run over them, which decreases friction and improves the efficiency of movement.