CorpusHuman Anatomy
SkeletalJoint

Joints of the hand

Articulationes manus

Also known as: carpometacarpal joint, CMC joint, metacarpophalangeal joint, MCP joint, interphalangeal joint, PIP, DIP, thumb CMC joint

The carpometacarpal, metacarpophalangeal and interphalangeal joints of the hand — including the saddle joint of the thumb — which together give the hand its range of grips and fine movements.

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Overview

Carpometacarpal (CMC) joints: the first CMC joint between the trapezium and the base of the 1st metacarpal is a saddle joint with a loose capsule, permitting flexion–extension, abduction–adduction, circumduction and, with axial rotation, opposition of the thumb. The CMC joints of the 2nd and 3rd metacarpals are almost immobile (the rigid central pillar); those of the 4th and especially 5th permit some flexion, allowing cupping of the palm.

Metacarpophalangeal (MCP) joints: condyloid joints allowing flexion–extension and abduction–adduction (plus limited circumduction). Each has a thick palmar plate (volar plate) and collateral ligaments that are lax in extension and tight in flexion (because the metacarpal head is cam-shaped) — hence hands are immobilised with the MCPs flexed to prevent contracture. The deep transverse metacarpal ligaments link the palmar plates of the fingers.

Interphalangeal (IP) joints — proximal (PIP) and distal (DIP) — are hinge joints, each with a palmar plate and collateral ligaments; the thumb has a single IP joint.

Location

Hand — between carpus and metacarpals, metacarpals and phalanges, and between phalanges.

Parts & subdivisions

  1. First CMC (saddle) joint
    Trapezium–1st metacarpal; opposition of the thumb.
  2. CMC joints 2–5
    Plane joints; 2nd–3rd rigid, 4th–5th mobile.
  3. MCP joints
    Condyloid; collateral ligaments tight in flexion.
  4. IP joints (PIP, DIP)
    Hinge joints with palmar plates.

Anatomy

Ligaments

Palmar (volar) plates, collateral ligaments, deep transverse metacarpal ligaments, dorsal and palmar CMC ligaments, anterior oblique ("beak") ligament of the thumb CMC.

Function

  • Opposition, pinch and power grip
  • Flexion, extension, abduction and adduction of the digits
  • Cupping and flattening of the palm

Clinical significance

Skier’s (gamekeeper’s) thumb

Rupture of the ulnar collateral ligament of the thumb MCP joint from forced abduction (fall on a ski pole); instability of pinch. A Stener lesion — adductor aponeurosis trapped between the torn ligament ends — prevents healing and requires surgery.

RA vs OA in the hand

Rheumatoid arthritis affects the MCP and PIP joints (sparing DIP): ulnar deviation, swan-neck (PIP hyperextension, DIP flexion) and boutonnière (PIP flexion, DIP hyperextension) deformities. Osteoarthritis affects the DIP (Heberden nodes), PIP (Bouchard nodes) and thumb CMC joints.

Volar plate injury

Hyperextension of a PIP joint ("jammed finger") avulses the palmar plate from the middle phalanx base.

Test yourself

Which joint is classified as a saddle (sellar) synovial joint?
  1. Carpometacarpal joint of the thumb
  2. Median atlanto-axial joint
  3. Radiocarpal joint
  4. Acromioclavicular joint

Answer: Carpometacarpal joint of the thumb

The first carpometacarpal joint (trapezium–1st metacarpal) is the classic saddle joint, allowing opposition. The median atlanto-axial is a pivot, the radiocarpal a condyloid (ellipsoid) and the acromioclavicular a plane joint.

More skeletal system questions

Compiled from standard anatomy and physiology references — see the Skeletal System sources. For education only; not medical advice.