Sesamoids are integral to the somewhat complicated suspensory apparatus, running down the back of the leg, that keeps the ankle-pastern from hyperextending during stance phase/weight-bearing.
Below the sesamoid bones (below ankle), there is no stretch to the ligaments that anchor the base of the suspens. apparatus. Above the sesamoids (lower leg, back of cannon bone) there is some give.
When you have an unfit horse, they tend to injure the tendons/ligaments above the sesamoid bones. When you have a fit, hard horse, if something blows, it\'s usually the sesamoid bones shattering/breaking apart as the \"weakest link\" in the suspensary apparatus.
It\'s physics.
