The skeletal system of the horse has three major functions in the body. It protects vital organs, provides framework, and supports soft parts of the body. Horses typically have 205 bones. The pelvic limb typically contains 19 bones, while the thoracic limb contains 20 bones.
Bones serve three major functions in the skeletal system; they act as levers, they store minerals, and they are the site of red blood cell formation. Bones can be classified into five categories
Ligaments and tendons hold the skeletal system together. Ligaments hold bones to bones and tendons hold bones to muscles. Synovial membranes are found in joint capsules, where they contain synovial fluid, which lubricates joints. Bones are covered by a tough membrane called periosteum, which covers the entire bone excluding areas of articulation.
Ligaments attach bone to bone, and are vital in stabilizing joints as well as supporting structures. They are made up of fibrous material that is generally quite strong. Due to their relatively poor blood supply, ligament injuries generally take a long time to heal.
Ligaments of the upper body include:
Ligaments of the legs include:
The axial skeleton contains the skull, vertebral column, sternum, and ribs. The sternum consists of multiple sternebrae, which fuse to form one bone, attached to the 8 "true" pairs of ribs, out of a total of 18.
The vertebral column usually contains 54 bones: 7 cervical vertebrae, including the atlas (C1) and axis (C2) which support and help move the skull, 18 (or rarely, 19) thoracic, 5-6 lumbar, 5 sacral (which fuse together to form the sacrum), and 15-25 caudal vertebrae with an average of 18. Differences in number may occur, particularly in certain breeds. For example, some, though not all, Arabians, may have 5 lumbar vertebrae, opposed to the usual 6, 17 thoracic vertebrae (and ribs) instead of 18, and 16 or 17 caudal vertebrae instead of 18. The withers of the horse are made up by the dorsal spinal processes of the thoracic vertebrae numbers 5 to 9.