Notes on Sesamoid Bones of the Upper Limb

Notes on Sesamoid Bones of the Upper Limb

Sesamoid bones are small rounded masses of bone located in some tendons at points where they are subjected to great pressure. They are variable in their occurrence. These are as follows.

1. The pisiform is often regarded as a sesamoid bone lying within the tendon of the flexor carpi ulnaris.

2. Two sesamoid bones are always found on the palmar surface of the head of the first meta­carpal bone.

3. One sesamoid bone is found in the capsule of the interphalangeal joint of the thumb, in 75% of subjects.

4. One sesamoid bone is found on the ulnar side of the capsule of the metacarpophalangeal joint of the little finger, in about 75% of subjects.

5. Less frequently, there is a sesamoid bone on the lateral side of the metacarpophalangeal joint of the index finger.

6. Sometimes sesamoid bone may be found at other metacarpophalangeal joints.