The hock, tarsus or uncommonly gambrel, is the region formed by the tarsal bones connecting the

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

and metatarsus of a digitigrade or unguligrade quadrupedal mammal, such as a

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...

, cat, or dog. This joint may include articulations between tarsal bones and the fibula in some species (such as cats), while in others the fibula has been greatly reduced and is only found as a

vestigial Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...

remnant fused to the distal portion of the tibia (as in horses). It is the anatomical homologue of the

ankle The ankle, the talocrural region or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joint. The ...

of the human

foot The foot (: feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is an organ at the terminal part of the leg made up o ...

. While homologous joints occur in other

tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...

s, the term is generally restricted to mammals, particularly long-legged domesticated species.

Horse

The terms ''tarsus'' and ''hock'' refer to the region between the gaskin (crus) and cannon regions (metatarsus), which includes the bones, joints, and soft tissues of the area. The hock is especially important in equine anatomy, due to the great strain it receives when the horse is worked. Jumping, quick turns or stops, and movements that require collection, are some of the more stressful activities.

Primary joints and bones of the hock

In the horse, the hock consists of multiple joints, namely: * Tibiotarsal or tarsocrural joint *Proximal intertarsal joint or talocalcanealcentroquartal joint *Distal intertarsal joint or centrodistal joint * Tarsometatarsal joint *Talocalcaneal joint In the horse, the hock consists of the following bones: * Talus *

Calcaneus In humans and many other primates, the calcaneus (; from the Latin ''calcaneus'' or ''calcaneum'', meaning heel; : calcanei or calcanea) or heel bone is a bone of the Tarsus (skeleton), tarsus of the foot which constitutes the heel. In some other ...

*Central tarsal bone *Fused 1st and 2nd tarsal bone *3rd tarsal bone *4th tarsal bone *2nd metatarsal bone *3rd metatarsal bone *4th metatarsal bone

Equine disease states

*Horses may suffer from "capped hock", which is caused by the creation of a false

bursa Bursa () is a city in northwestern Turkey and the administrative center of Bursa Province. The fourth-most populous city in Turkey and second-most populous in the Marmara Region, Bursa is one of the industrial centers of the country. Most of ...

, a synovial sac beneath the skin. Capped hock is usually caused by trauma such as kicking or slipping when attempting to stand. In the absence of a wound, it does not require immediate veterinary attention and is usually only of cosmetic significance. On the other hand, a wound into the calcanean bursa is a serious problem. A capped hock is extremely unlikely to be a cause of lameness, even if severe. *Osteochondrosis dissecans, or OCD is a developmental defect in the cartilage or of cartilage and bone seen in particular locations on the surface of the tarsocrural joint. This condition is typically discovered when the horse is young, and is one cause of bog spavin. After surgery to remove bone and cartilage fragments most horses can return to full work. *Distension of the tibiotarsal joint with excessive joint fluid and/or synovium is called bog spavin. *Degenerative joint disease of the tarsometatarsal and/or distal intertarsal joint is referred to as bone spavin. *

Curb A curb (American English) or kerb (British English) is the edge where a raised sidewalk/pavement or road median/central reservation meets a street/other roadway. History Although curbs have been used throughout modern history, and indeed ...

, or tarsal plantar desmitis, is traditionally considered a sprain of the plantar ligament, which runs down the back of the hock, serving functionally as a tension band connecting the calcaneus, the fourth tarsal bone and the fourth metatarsal bone. Recent work has shown that curb can be caused by damage to one of many soft tissue structures in this region. * Stringhalt

Conformational defects

''Also see

equine conformation Equine conformation evaluates a horse's bone structure, musculature, and its body proportions in relation to each other. Undesirable conformation can limit the ability to perform a specific task. Although there are several faults with univers ...

'' Because the hock takes a great deal of strain in all performance disciplines, correct conformation is essential if the horse is to have a sound and productive working life. Common conformational defects include sickle hocks, post-legged conformation/straight hocks, cow hocks, and bowed hocks. Depending on the use of the horse, some defects may be more acceptable than others.

References

{{reflist Mammal anatomy Horse anatomy

Horse

Primary joints and bones of the hock

Equine disease states

Conformational defects

See also

References