1. Tarsus Anatomy
Dane Tatarniuk, DVM

2. Bones
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Talus b.
Calcaneus b.
Central tarsal b.
1st & 2nd (fused) tarsal b.
3rd tarsal b.
4th tarsal b.
• Proximally: Tibia
• Distally: 2nd, 3rd, 4th metatarsal b.

3. Dorsal-Plantar
Lateral-medial

4. DLPMO
DMPLO

5. PMDLO
PLDMO

6. Plantar-Dorsal

7. Joints
• Tarsocrural
• Talocalcaneal
• Proximal Intertarsal
• Talocalcaneal-Centroquatral
• Distal Intertarsal
– Centrodistal
• Tarsometatarsal

8. Tarsocrural
• Ginglymus Joint
– Hinge-like joint, direction in only one plane
– Deep grooves in cochlear surface of distal tibia,
and trochlea of the talus
• Articulation
– 12 to 15 degrees to the sagittal plane, in dorsallateral direction

9. PIT / DIT / TMT
• Plane joints
• Only a very limited gliding movement

10. Joint Capsule
• Proximal: attaches to distal aspect of the tibia
• Distal: attaches to metatarsal bones
• Joint Pouch Effusion:
– Dorsal-medial aspect of joint capsule, at level of
medial trochlea
– Proximal aspect of plantar joint capsule, at level of
talus and distal tibia, both medial/lateral side

11. Ligaments
• Lateral Long Collateral Ligament
– Superficial
– Originate: Caudal aspect of lateral malleolus of
distal tibia
– Inserts: Fourth tarsal b., third metatarsal b., fourth
metatarsal b.
– Forms canal for lateral digital extensor tendon

12. Ligaments
• Lateral Short Collateral Ligament
– Deep to long collateral
– Originates: Cranial aspect of lateral malleolus of
the distal tibia
– Runs caudally
– Insertion: Lateral aspect of calcaneus

13. Ligaments
• Medial Long Collateral Ligament
– Originates: Caudal aspect of medial malleolus of
distal tibia
– Insertion: Second metatarsal b., third metatarsal
b., medial aspect third tarsal b.

14. Ligaments
• Medial Short Collateral Ligament
– Deep to medial long collateral
– Originates: Cranial aspect of the medial malleolus
of distal tibia
– Insertion: Medial aspect of the calcaneus and
sustentaculum tali

15. Ligaments
• Long Plantar Ligament
– Strong, flat band
– Originates: Proximal plantar aspect of calcaneus
– Insertion: Fourth metatarsal b., fourth tarsal b.

16. Ligaments
• Dorsal tarsal ligament
– Originates: Distal tuberosity of the talus
– Insertion: Central tarsal b., third tarsal b., proximal
third metatarsal b.

17. Muscle/Tendons
• Cranial-lateral
– Tibialis cranialis
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Flexor of hock
Originates from lateral condyle of tibia
Tendon passes through split in peroneus tertius
Tibialis cranialis tendon then splits itself
Insertion:
– Dorsal branch, proximal third metatarsus
– Medial branch, crosses the medial long collateral ligament and
inserts on the fused 1st & 2nd tarsal bone
• Innervated by peroneal nerve

18. Muscle/Tendons
• Cranial-lateral
– Peroneus tertius
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Originates from distal femur
Courses alongside the long extensor muscle
Bifurcates at the dorsal tarsus
Lateral branch inserts on calcaneous b. and fourth
tarsal b.
• Dorsal branch inserts on the proximal third metatarsal
• Links the flexion of hock and stifle
• Innervated by peroneal nerve

19. Muscle/Tendons
• Cranial-lateral
– Long digital extensor
• Originates from distal femur
• Inserts on the extensor process of third phalanx
• Lateral extensor tendon joins into long at level of
proximal metatarsus
• Tendon sheath present as it crosses the dorsal tarsus
• Held in place by 3 retinacula
• Synovial sheath present
• Flexes the hock, extends the digit
• Innervated by peroneal nerve

20. Muscle/Tendons
• Cranial-lateral
– Lateral digital extensor
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Originates lateral collateral ligament of stifle
Inserts (joins) into the long extensor tendon
Held in place by retinaculum
Synovial sheath present
Innervated by peroneal nerve
– Extensor digitalis brevis
• Small, short digital extensor tendon between the angle of
the long and lateral digital extensor tendons

21. Muscle/Tendons
• Caudal
– Gastrocnemius
• Originates from 2 heads on the supracondylar
tuberosities of the femur, superficial to SDFT
• Inserts on the points of the calcaneus, deep to
superficial digital flexor tendon
• Extends the hock
• Innervated by tibial nerve

22. Muscle/Tendons
• Caudal
– Superficial digital flexor
• Originates from the supracondylar fossa of femur, deep
to gastrocnemius
• Twists medially to become superficial to gastrocnemius
• Medial and lateral aspects insert on the point of the
calcaneus
• Remainder of SDFT continues down plantar aspect of
distal limb, inserts on first and second phalanx
• Innervated by tibial nerve

23. Muscle/Tendons
• Caudal
– Deep digital flexor tendon
• Originates from three heads
– Lateral digital flexor & Tibialis caudalis
» Originates from caudal tibia
» Become joined, pass through the sustentaculum tali
» Tarsal sheath
– Medial digital flexor
» Originates from lateral condyle of tibia
» Passes within groove on medial malleolus and medial
collateral ligament
• Innervated by tibial nerve

24. Tendon Sheaths
• All the tendons
coursing over
the hock, with
exception of
superficial
digital flexor
tendon, have a
concurrent
tendon sheath

25. Bursas
• Cunean Bursa
– Directly deep to the
cunean tendon
• Calcaneal Bursa (2)
– Subcutaneous
– Subtendinous

31. Nerves & Vessels

32. Nerves & Vessels

33. References
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Dr. Alexander zur Linden, http://vetmed.iastate.edu/limbanatomy/horse.html
Horowitz A., Berg R., “Anatomy of the Horse”, 5th ed.
Moyer, “Equine Joint Injection and Regional Anesthesia”, 3rd ed.