Middle phalanx of ring finger: anatomy, location and function

What it is

The middle of the three phalanges of the ring finger (fourth 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

FMA23942 (Foundational Model of Anatomy)

Key facts

• The central slip of the extensor expansion inserts on the dorsal side of its base.
• The palmar skin of the ring finger is split: the radial half is supplied by the median nerve and the ulnar half by the ulnar nerve.
• The thumb has no middle phalanx.

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