📝 STANDARD DESCRIPTION:
Complex joint between leg and metatarsus. Hock = clinical name.
Ox Standard — 5 bones in 3 rows:
Proximal row:
- Talus (Tibial tarsal) — pulley with 2 trochleae (proximal & distal).
- Calcaneus (Fibular tarsal) — has long lever (Tuber Calcanei = 'point of the hock').
Middle row:
- Central tarsal + 4th tarsal FUSED = 'Centroquartal' (unique to ruminants).
Distal row:
- 1st tarsal (small, separate)
- 2nd + 3rd tarsals FUSED
Tuber Calcanei: caudal projection of calcaneus; tendon of GASTROCNEMIUS attaches here ('Achilles tendon').
Total: 5 bones in ox (vs. 6 in horse, 7 in dog).
📚 DETAILED DESCRIPTION:
TARSUS / HOCK — the ankle of the hindlimb
The hock is a complex joint made of multiple small bones (tarsals) arranged in 3 rows. It works mainly as a hinge.
BONES OF OX HOCK (5 total):
Proximal row (2 bones):
1. Talus (Tibial tarsal): Has TWO pulleys (proximal trochlea articulates with tibia, distal trochlea with central tarsal). The double pulley is unique to ruminants.
2. Calcaneus (Fibular tarsal): Largest tarsal bone. Sticks up behind as a lever — its top is the tuber calcanei (point of hock). The big gastrocnemius tendon ('Achilles tendon') attaches here.
Middle row (1 bone in ox):
3. Centroquartal: A FUSION of central tarsal + 4th tarsal — characteristic of ruminants.
Distal row (2 bones in ox):
4. 1st tarsal: Small, separate bone on the medial side.
5. Fused 2nd+3rd tarsal: Single bone — fuses for greater weight-bearing.
So total in OX = 5 bones.
POINT OF HOCK = tuber calcanei. Bursa over it can become inflamed → 'capped hock'.
CHESTNUT in horse hindlimb = horny remnant on medial side of tarsus, considered vestige of carpal/tarsal pad.
// COMPARATIVE ANALYSIS
| HORSE |
6 bones — talus, calcaneus, central, 1st, 2nd+3rd fused, 4th. Single trochlea on talus. |
| DOG |
7 bones — talus, calcaneus, central, 1st, 2nd, 3rd, 4th (all separate). |
| PIG |
7 bones (like dog) — complete pattern. |
| FOWL |
Proximal tarsals fuse with TIBIA → tibiotarsus. Distal tarsals fuse with metatarsals → tarsometatarsus. NO separate ankle joint — the joint is intratarsal. |
CLINICAL RELEVANCE
Capped Hock: Bursitis over the tuber calcanei from kicks against walls or trailers — visible swelling on the back of the hock.
Bone Spavin: Osteoarthritis of the lower hock joints (between distal tarsals and metatarsus) — common cause of hindlimb lameness in horses.
Curb: Strain of the long plantar ligament behind the hock.
