Skeletal System of The Horse - Ligaments

Ligaments

Ligaments attach bone to bone, and are vital in stabilizing joints as well as supporting structures. They are made up of fibrous material that is generally quite strong. Due to their relatively poor blood supply, ligament injuries generally take a long time to heal.

Ligaments of the upper body include:

• Nuchal and supraspinous ligaments: the nuchal ligament attaches to the dorsal surface of the cervical vertebrae. Its dorsal section extends from the occipital protuberance of the skull (the poll) to the withers, then narrows to become the supraspinous ligament. It also connects the 2-7th cervical vertebrae to the 1-3rd thoracic vertebrae. Its main purpose is to support the head and allow it to be moved upward or downward.
• Intercapital ligaments: lie between the first through eleventh ribs. Help to prevent thoracic disk herniation.

Ligaments of the legs include:

• Suspensory ligament: runs from the back of the cannon bone (between the two spint bones), then splits into two branches and attaches to the sesamoid bones at the bottom of the fetlock. Branches continue downward and attach to the extensor tendons. The main purpose of the suspensory is to support the fetlock joint, preventing it from overextending. Injury to this ligament is an important cause of lameness in performance horses. The suspensory is a modified muscle, the equine equivalent of the interosseous muscle, which contains both tendon fibers and residual muscle fibers.
• Interosseous ligaments: connect the cannon bone to each splint bone. Injury to this ligament produces the condition known as "splints".
• Proximal and distal check ligaments: The proximal check ligament originates from the radius and attaches to the superficial digital flexor tendon. The distal check originates from the palmar carpal ligament and attaches to the deep digital flexor tendon, approximately 2/3-way down the metacarpus.
• Plantar ligament: in the hind leg, runs down the lateral side of the tarsus, attaches to the fibular, 4th tarsal, and 3rd metatarsal bones. Injury leads to a condition known as "curb."
• Inter-sesamoidean ligaments: supporting ligaments, run between the two sesamoid bones.
• Distal sesamoidean ligaments: run from the sesamoid bones to the two pastern bones. Important in the stay apparatus.
• Impar ligament: runs between the navicular bone and the 3rd phalanx.
• Annular ligament: goes around the back of the fetlock, surrounding the flexor tendons and their tendon sheath, attaching to the sesamoid bones. It helps to support the fetlock, and provides an enclosed "pulley" for the flexor tendons to run through.
• Sacrosciatic ligament: Originates from the sacrum and coccygeal vertebrae, inserts into the pelvis.