ANATOMY LESSON

ANATOMY ANATOMY LESSON

Identifying the bones of the lower front limb

Understanding the anatomy of the horse is valuable knowledge for riders and important for injury prevention. Here, we will identify the basic parts of the horse’s skeletal structure and see how its frame compares to that of the human skeleton. Of course, large differences occur (for example, our two legs compared to the horse’s four,) but there are several bones in our bodies that perform similar functions to those of the horse. Knowing the basic parts of horse also helps us realize their form to function.

1. Radius - The larger of the two bones of the forearm. The radius is the main bone that attaches to the humerus at the proximal end and articulates with the carpal bones at the distal end. 2. Knee - The horse’s knee/carpus is made up of two rows of bones with four bones in each row. These bones are located very close to the horse’s skin and there is little movement within the bones. As humans, we have carpal bones as well, but ours are located in our wrist.

3. Cannon Bone - This is the strongest bone in the horse’s body. Articulates with the second row of carpal bones and forms the carpal/metacarpal joint. Distally articulates with the long pastern bone and joins with the fetlock joint. 4. Splint Bones - These bones in the horse are rudimentary structures and although they are present, they don’t serve much of a useful purpose as a result of evolution. The splint bones are attached by the interosseous ligaments to the cannon bone. As humans, we have metacarpal bones in our hands. 5. Fetlock - This is a term used for the joint where the cannon bone, the proximal sesamoid bones, and the first phalanx (long pastern bone) meet. The pastern is the area between the hoof and the fetlock joint. The fetlock resembles the human ankle, but is more anatomically similar to the ball of the foot. The fetlock is subject to a lot of stress and strain.

6, 7, & 8 - Pastern Bones - The portion of the horse’s foot occupied by the first and second phalanges. As humans, we have phalanges too: our fingers and toes. 9. Coffin Bone - Or third phalanx is entirely enclosed by the hoof. The general shape of the bone conforms to the hoof itself and it is connected to the deep digital flexor tendon. AB

BY JENN WEBSTER

COMMON NAME

1. Forearm 2. Knee 3. Cannon Bone 4. Splint Bones 5. Fetlock 6. Pastern 7. Long Pastern Bone 8. Short Pastern Bone 9. Coffin Bone

ANATOMICAL TERM

Radius Carpal Joint (Carpus) Third Metacarpal Second and Fourth Metacarpal Metacarpophalangeal Joint Interphalangeal Joint First Phalanx (Proximal) Second Phalanx (Middle) Third Phalanx (Distal)

NOMENCLATURE:

Anterior: toward the front Posterior: toward the back Ventral: relating to the underside Dorsal: relating to the upper side Superior: higher in position Inferior: lower in position Cranial: toward the head Caudal: toward the tail Medial: toward the midline of the body Lateral: toward the outside of the body (away from the midline) Proximal: toward the centre of the body Distal: away from the centre of the body Palmar: back part of the front limb (carpus down) Plantar: back part of the hind limb (tarsus down)