scutum

[Latin scūtum, shield.]

1. scute.
2. a protective covering or shield, e.g. a chitin plate in the exoskeleton of hard-bodied ticks.
3. a pressure pad that serves as a bearing surface for tendons as they bend around a prominence. The horse digit bears three scuta over the fetlock, pastern and coffin joints for the passage of the deep digital flexor tendon.