Fetlock
Overview
Joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...
s (MCPJ and MTPJ) of horse
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
s, large animals, and sometimes dogs. It is formed by the junction of the third metacarpal (forelimb) or metatarsal (hindlimb) bones (common name: the cannon bones) proximad and the proximal phalanx distad (common name: the pastern
Pastern
The pastern is a part of the leg of a horse between the fetlock and the top of the hoof. It incorporates the long pastern bone and the short pastern bone , which are held together by two sets of paired ligaments to form the pastern joint...
bone). Paired proximal sesamoid bones articulate with the palmar or plantar distal surface of the third metacarpal or metatarsal bones and are rigidly fixed to the proximo-palmar / -plantar edge of the proximal phalanx.
The fetlock is a hinge joint
Hinge joint
A hinge joint is a bone joint in which the articular surfaces are molded to each other in such a manner as to permit motion only in one plane—backward and forward—the extent of motion at the same time being considerable....
(ginglymus), allowing flexion
Flexion
In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal and muscular systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder...
and extension
Extension (kinesiology)
In kinesiology, extension is a movement of a joint that results in increased angle between two bones or body surfaces at a joint. Extension usually results in straightening of the bones or body surfaces involved. For example, extension is produced by extending the flexed elbow. Straightening of...
, but minimal rotation
Rotation
A rotation is a circular movement of an object around a center of rotation. A three-dimensional object rotates always around an imaginary line called a rotation axis. If the axis is within the body, and passes through its center of mass the body is said to rotate upon itself, or spin. A rotation...
, adduction
Adduction
Adduction is a movement which brings a part of the anatomy closer to the middle sagittal plane of the body. It is opposed to abduction.-Upper limb:* of arm at shoulder ** Subscapularis** Teres major** Pectoralis major** Infraspinatus...
, or abduction
Abduction (kinesiology)
Abduction, in functional anatomy, is a movement which draws a limb away from the median plane of the body. It is thus opposed to adduction.-Upper limb:* of arm at shoulder ** Supraspinatus** Deltoid* of hand at wrist...
.
While sometimes the fetlock is colloquially referred to as an "ankle," even by horse experts, that terminology is not correct.
