Sesamoid

Sesamoid bones are a type of bone that are embedded within a tendon or a muscle. They are named for their resemblance to a sesame seed. The most commonly known sesamoid bones are the patella (knee cap) and the bones under the base of the big toe.

Function

Sesamoid bones act like pulleys, providing a smooth surface for tendons to slide over, increasing the tendon's ability to transmit muscular forces. They can also modify pressure, reduce friction, and sometimes alter the direction of muscle pull.

Examples

The largest sesamoid bone in the body is the patella, other examples include the pisiform (smallest of the carpal bones in the hand), and the two sesamoid bones under the base of the big toe.

Clinical significance

Injury to a sesamoid bone can often be painful and disabling. A common injury to the sesamoid bone is a fracture, which can be caused by trauma or overuse. Other conditions that can affect the sesamoid bones include sesamoiditis, turf toe, and hallux rigidus.

See also

• Bone
• Tendon
• Patella
• Pisiform
• Sesamoiditis
• Turf toe
• Hallux rigidus

Sesamoid Resources
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