Overview
The tarsus (ossa tarsi) is the group of short bones of the hock, between the tibia and fibula proximally and the metatarsal bones distally. The cat has seven tarsal bones arranged in several rows. In the normal digitigrade stance the tarsus is raised off the ground and the joint is held at an angle.
Bones
- Talus: proximal row, medial. Its trochlea fits the cochlea of the tibia and forms the tarsocrural joint, where almost all tarsal movement takes place.
- Calcaneus: proximal row, lateral. Its tuber (tuber calcanei) forms the point of the hock and receives the common calcaneal tendon (gastrocnemius, superficial digital flexor and others), which extends the tarsus. The sustentaculum tali supports the talus medially and guides the tendon of the deep digital flexor.
- Central tarsal bone: between the proximal and distal rows, on the medial side.
- Tarsal bones I to IV: distal row; bone IV is the largest and spans two levels on the lateral side.
Clinical relevance
- Plantigrade stance: resting the tarsus and metatarsus on the ground is a classic sign of diabetic neuropathy in the cat; it also appears with injuries of the common calcaneal tendon and the sciatic nerve.
- High-rise syndrome: the tarsus is among the limb regions injured.
- Scottish Fold osteochondrodysplasia: exostoses on the plantar side of the tarsus and metatarsus, with stiffness, pain and lameness.
- Fractures, luxations and shearing injuries of the tarsus after road accidents, often open.