A horse skeleton diagram shows the bones that are needed for the body of a horse to function. These are held together by ligaments and tendons which are attached to the bones by muscles. When the proportions of these are right they work together well. If the proportions are wrong, or if the muscles become tight, then injury is more likely to occur.
The hind limbs are made up of the pelvic girdle, femur, tibia and fibula, metatarsal bones and phalanges, as well as sesamoid bones. The phalanges are divided into proximal and distal phalanges. The proximal phalanges are smaller and shorter than the distal phalanges. The phalanges are connected to the ankle bone, called the talon and the toe bones, which connect the phalanges to the foot. The foot is a complex structure, containing many joints. The horse is unique among domestic species in that it has a pedal bone that supports the back of the hoof. This has a high density of blood vessels around it, which supply nutrients for the growth of new hoof horn and help to absorb impact shock from walking and running.
There are two main groups of muscles in the horse which are responsible for the movement of the legs, including the flexor muscle which enables a horse to walk, trot and gallop and the extensor muscle which allows the hind limbs to bend at the knee and hock. Other important muscles include the triceps femoris and semitendinosus which enable the horse to flex its elbow, shoulder and humerus joints.
The humerus is a large flat bone that articulates with the scapula and the radius and ulna at the shoulder and elbow joints respectively. This is one of the strongest bones in the body.
Another equine characteristic is the arrangement of the articular surfaces of the bones in the forelimbs, which allow them to move more easily and generate greater propulsion than other ungulates. This is achieved by a combination of the flexion of joints and muscle action to accumulate the energy required for jumping.
The horse is the only domestic animal with a pedal bone which is the support for the back of the hoof. This is a unique feature which gives the hoof its high level of strength and stability, as well as providing an effective way of absorbing impact shock and regulating temperature. It also has an unusually high density of blood vessels. The blood is pumped into the hoof by two major arteries which run down the back of the leg, and into the hoof wall itself by the laminae that hold the hoof walls to the inside structures of the hoof. This blood circulation provides nutrients to the keratinous keratin, which grows over the dorsal surface of the pedal bone. It also nourishes the inner structures of the hoof, including the vascular network and the intertubular horn. The lateral hoof wall is covered in solar corium, which produces the sole of the foot.