fetlocks

The fetlock is a term used in equine anatomy to refer to the joint between the cannon bone and the proximal phalanx, also known as the metacarpophalangeal joint in the forelimb or metatarsophalangeal joint in the hind limb. The word also describes the region around this joint, including the distinctive tuft of hair that covers the area.

Anatomy and components: The fetlock joint connects the cannon bone (the third metacarpal/metatarsal) to the proximal phalanx (P1). It is reinforced by the medial and lateral collateral ligaments and the palmar (or plantar) ligament. Behind the joint lie the proximal sesamoid bones, which interact with the suspensory apparatus. The suspensory ligament runs along the back of the cannon bone and contributes to joint stability, while the flexor and extensor tendons cross the area to control movement.

Function: The fetlock functions as a hinge that permits flexion and extension of the limb. It bears substantial weight during stance and contributes to propulsion during the horses' stride, absorbing impact and enabling locomotion.

Clinical notes: Fetlock injuries are common in performance horses and can involve soft tissue structures such as the suspensory ligament, as well as fractures of the proximal sesamoid bones or degenerative changes in the joint. Diagnosis typically relies on clinical examination and imaging.

See also: In the broader context of limb anatomy, the fetlock is a key component of the equine locomotor system and is often a focus in veterinary medicine due to its role in athletic performance and injury risk.