Anatomy Lesson, Part 3

Happy 2012 everybody!

It\’s been a while since we touched base on equine anatomy, but I figured, \”Why not ring in the new year on an intellectual note…?\”

Ha! Don\’t expect this to continue on year round… <grin>

Since the last MSL focus on anatomy, which identified bones of the horse’s lower front limb, it’s now time to examine the bones of the horse’s hind limb. Yeah, wahoo!!

I know you’re all ecstatic!

However, on a serious note, it’s very helpful to know what equine parts go where and what they are termed anatomically – especially if you’re trying to decipher what it is your vet is saying in the event of a check-up or emergency.

Just like last time, let’s talk a look at the common terms for the hind limbs, map them and compare those terms to their anatomical terms.

Common Name                Anatomical Term
1.           Gaskin                              Tibia
2.           Hock                                Tarsal Joint
3.           Cannon Bone                3rd Metatarsal
4.           Splint                              2nd & 4th Metatarsal
5.           Fetlock                           Metatarsalphalangeal Joint
6.          Pastern                            Interphalangeal Joint
7.          Coffin Bone                    3rd Phalanx (Distal)
8.        Navicular Bone                Distal Seisamoid Bone

1. Gaskin – The tibia or gaskin carries the entire weight of the horse’s hind limb. The tibia articulates with the femur to form the horse’s stifle joint.

2. Hock – The tarsal joint is comprised of 3 rows of tarsal bones and four joints. It coincides to the back. Medial in row 1 is the talus or tibial tarsal bone. Lateral in row 1 is the fibular tarsal bone of calcaneous, which creates the point of the hock and coincides to the back of the heel in humans.

3. Cannon Bone – The 3rd Metatarsal is the strongest bone in the horse’s body. In the hind limb, it articulates with the tarsal bones and forms the tarsal joint. Distally it joins with the fetlock joint.

4. Splint – Splint bones are attached by interosseus ligaments to the cannon bones.

5. Fetlock – The fetlock serves as an attachment part for the distal part of the suspensory ligament and is subject to a lot of stress and strain.

6. Pastern – The portion of the horse’s lower limb occupied by the first and second phalanges (Long Pastern Bone and Short Pastern, please see Anatomy of Front Limb for more info). As humans, we have phalanges too: our fingers and toes.

7. Coffin Bone – Or 3rd phalanx, is entirely enclosed by the hoof. The general shape of the bone conforms to the hoof itself and it is intimately related to the deep digital flexor tendon.

8. Navicular Bone – Or the Distal Sesamoid Bone is a small bone found in the feet of both humans and horses. The navicular bone of the horse lies on the palmar aspect of the coffin joint between the second phalanx and third phalanx, known as the coffin or pedal bone. It is an important structure in relation to lameness and is involved with a significant disease process called Navicular Disease.