Sesamoid Bones of the Thumb

Description

Xray of the thumb with the sesamoids highlighted

Sesamoid bones of the hand

Name

• Thumb Sesamoids
• Pollicis Sesamoid
• 1st metacarpophalangeal joint sesamoid
• Sesamoid Bones of the Thumb
• Sesamoids of the Thumb
• First Metacarpophalangeal Sesamoids
• First MCP Sesamoids
• Pollical Sesamoids
• Radial and Ulnar Sesamoids of the Thumb
• Os Sesamoideum Pollicis

General

• Two or three sesamoid bones are typically present in the thumb
• Two are always present at the metacarpophalangeal joint
• One is present at the interphalangeal joint in 60-80% of individuals

Metacarpophalangeal Joint Sesamoids

• The sesamoids lie within a volar plate
• Articulate with the volar condyles of the metacarpal head
• Ulnar metacarpal condyle is relatively concave and grooved, which accepts the sesamoid
• Radial condyle is convex and articulates with the concavity of the radial sesamoid
• The flexor pollicis brevis tendon inserts on the radial sesamoid
• The adductor pollicis inserts on the ulnar sesamoid
• They also accept attachments from the accessory collateral ligaments dorsally, A1 pulley volarly
• The flexor pollicis longus tendon passes between the two sesamoids

Interphalangeal Joint Sesamoid

• A single sesamoid in the flexor pollicis longus-volar plate complex
• Articulates with the head of the proximal phalanx

Function Protect and guide the tendon of FPL

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Clinical Significance

• Sesamoiditis of the Thumb
• Sesamoid Fracture of the Thumb

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See Also

• Finger Pain Main
• Hand Anatomy Main
• Physical Hand Exam

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