|The basis of support and movement of the
horse is made possible by the combined effort of the skeletal and
systems. In this article we will look closely at
the skeletal system.
system includes all bones attached at joints, cartilage between the
joints & fibrous ligaments. The system has several roles in the physiology of the horse, these
support of the soft tissues, providing the framework of the horse's
â€¢ protection of delicate internal organs
â€¢ leverage -
providing attachment for ligaments, muscles and tendons
â€¢ mineral storage - especially
calcium and phosphorus
â€¢ blood cell production takes
place in the marrow of many long bones
A bone is a living tissue with
nerves and blood vessels. It contains proteins and minerals,
particularly calcium and phosphorus. To achieve and maintain a
healthy skeleton the horse must receive adequate amounts of these
Bone consists of the hard outer cortex,
encasing an inner area of spongy bone, called the medullary cavity.
Within this cavity is the marrow, where new blood cells are made. The
entire surface of the bone is covered by a thin membrane called the
On the basis of shape, bones are classified as either -
long bones such as the cannon or radius
short bones such as the carpal and
flat bones such as the scapula
irregular bones such as the vertebrae
A joint (or articulation) is a point
of contact between bones or between cartilage and bones. Joints allow
movement. They may be classified into the following types -
fibrous joints - bones held by fibrous
connective tissue, with no joint cavity (e.g. the skull). Allow little or
(Left - synovial joint)
cartilaginous joints - bones held by
cartilage, with no joint cavity (e.g. the vertebrae). The articulating
bones are held together tightly, allowing little movement.
synovial joints - contain a joint (synovial)
cavity, articular cartilage and a synovial membrane (e.g. the fetlock).
A fully moveable joint.
Cartilage is a gristly connective tissue containing collagen and
elastic fibres covering the ends of bones at some joints. It
contains no blood vessels or nerves.
A ligament is a dense fibrous tissue
that connects bone to bone.
Horses also have "check ligaments" which connect some bones & tendons and
form part of the horse's "stay mechanism". They lock the limbs and joints
so that the horse can relax and sleep in a standing position.
Tendons connect muscle to bone and
help control the movement of bones and joints. In the horse there are no muscles below the
knee or hock. All movement of the pastern and foot is transferred by
tendons connected to muscles in the upper limbs.
Both tendons and ligaments have a poor
blood supply, making healing difficult following injury.
The skeletal system consists of
approximately 205 bones divided into -
the axial skeleton includes all but the limbs - the skull, vertebrae, sternum
and ribs and the appendicular skeleton - including the four limbs of the
horse. There is variation in the number of bones, as some fuse
together as the horse matures. Even in adult horses there can be variation
in the number of bones. E.g. anything from 15 to 21 coccygeal or caudal (tail)