Middle phalanx of middle finger: anatomy, location and function

What it is

The middle of the three phalanges of the middle finger (third digit).

Location

Lies between the proximal and distal phalanges, forming the proximal and distal interphalangeal joints.

Function

Allows the finger to curl; flexor digitorum superficialis inserts along its sides to flex the proximal interphalangeal joint.

Body system

Skeletal · paired (left and right)

FMA ID

FMA23940 (Foundational Model of Anatomy)

Key facts

• The central slip of the extensor expansion inserts on the dorsal side of its base.
• Its palmar skin and nail bed are supplied by palmar digital branches of the median nerve.
• It is the longest middle phalanx, matching the middle finger as the longest digit.

Clinical relevance

Rupture of the central slip over its base lets the proximal interphalangeal joint buckle through the extensor hood, producing a boutonnière deformity.

The nearest named structures in the 3D model, measured from the centre of each part:

• Distal phalanx of middle finger · skeletal
• Middle phalanx of ring finger · skeletal
• Middle phalanx of index finger · skeletal
• Distal phalanx of ring finger · skeletal
• Distal phalanx of index finger · skeletal
• Proximal phalanx of middle finger · skeletal
• Proximal phalanx of index finger · skeletal
• Proximal phalanx of ring finger · skeletal
• Distal phalanx of little finger · skeletal
• Middle phalanx of little finger · skeletal