Tendons and ligaments are tough fibrous structures found all over the body, securing the muscles to the bones. However, the horse’s lower leg has no muscles, only bones, tendons and ligaments.
Due to the large amounts of pressure applied to them, tendons and ligaments are highly susceptible to strain and injury, therefore it is worth knowing about them in order to prevent strain.
- Tendons – A fibrous cord that attaches muscles to bones, however, in the lower leg, they are very long, and connect from bone-to-bone.
- Ligaments – These are fibrous bands found in joints, they help secure cartilage to bone. Similar to tendons, however less elastic.
- proximal – Closer to the body (top of the leg)
- distal – further from the body (bottom of the leg)
- medial – Inner aspect of leg
- Lateral – Outer aspect of leg
- Dorsal – Front of leg (when describing below carpus/tarsus (knee/hock))
- palmar/plantar – refers to the back of the leg (when describing below carpus/tarsus (knee/hock))
Estimates claim that over 30% of competitive horses in racing and eventing suffer tendon injuries. This is because huge amounts of strain, and weight are put on legs that are (compared to body mass) very thin.
All muscles end before and around the carpus (knee), continuing distally from the carpus as tendons. These end on the phalangeals, the equivalent to our fingers.
The tendons found behind the cannon bone are flexor tendons, responsible for flexing the leg at the fetlock. These are highly susceptible to damage, as competing puts an enormous strain on these. The tendons at the front of the leg are the extensors, responsible for extending the tendons. These are less susceptible to damage.
Located behind the cannon bone are two tendons, known as the superficial, and the deep flexor tendons. These can be felt as the ”fleshy cords” behind the cannon bone. These attach to the phalanges, and are held in place by three annular ligaments. The deep flexor is also strengthened by the accessory check ligament. In between the deep flexor and the cannon bone is the interosseus ligament, or suspensory ligament. This runs from the carpus to the sesamoid bones in the fetlock joint where it divides into two, continuing down the leg to join the common extensor tendon.
The common extensor tendon runs down the front of the leg and allows the horse to lift the toe and extend the foot. This is the main extensor tendon, hence the name ”common”.
The lateral digital extensor extends the pastern and carpus and inserts between the first phalanx.