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Joints of the Hand

Articulationes manus

For medical students2 min readUpdated 2026-10-10

The joints of the hand form a complex biomechanical chain that provides both power grips and delicate, highly precise manipulations. This system includes articulations between the forearm bones, the two rows of carpal bones, the metacarpals, and the phalanges of the digits.

Radiocarpal jointEllipsoid, biaxial joint articulating the radius and the carpus
Carps cleftThe midcarpal joint features a characteristic S-shaped joint space
Thumb1st carpometacarpal joint is a saddle joint with unique mobility

Radiocarpal Joint

In its structure, the radiocarpal joint (articulatio radiocarpalis) is an ellipsoid and biaxial joint. It serves as the primary mechanical link between the forearm and the hand.

The articular surfaces are formed by:

The joint capsule is thin and attaches strictly along the margins of the articulating surfaces. The joint is reinforced by several ligament groups:

  1. Collateral ligaments: ligg. collateralia ulnare et radiale.
  2. Palmar and dorsal ligaments: ligg. radiocarpalia dorsalia et palmaria.

Biaxial construction allows flexion and extension, as well as abduction and adduction. A combination of these movements permits circumduction.

Carpal Joints

The anatomy of the carpus includes several groups of articulations that ensure structural integrity and flexibility of this region.

Midcarpal joint (articulatio mediocarpalis) lies directly between the proximal and distal rows of carpal bones. It is a complex and combined articulation characterized by an S-shaped joint space. Its capsule is shared with the intercarpal joints. Notably, this joint is biomechanically linked to the radiocarpal joint—their movements occur in synergy.

Intercarpal joints (articulationes intercarpales) are located between the individual bones of each carpal row. They are planar in shape and classified as amphiarthroses (slightly movable joints). Additional stability is provided by strong interosseous ligaments.

Metacarpal Joints and Thumb Articulation

Carpometacarpal joints (articulationes carpometacarpales) connect the bases of the 2nd–5th metacarpal bones with the distal row of the carpus. They are also planar and slightly movable.

However, there is a prominent exception: the 1st carpometacarpal joint (the thumb articulation). Its shape is sellar (saddle), which dictates its high mobility. Thanks to this joint, the thumb can perform flexion and extension, abduction and adduction, and most importantly, opposition (oppositio) to the other digits and reposition (repositio).

Between the bases of the 2nd–5th metacarpal bones, there are also intermetacarpal joints (articulationes intermetacarpales). They are planar in shape and reinforced by corresponding ligaments.

Joints of the Digits

Finger movements are executed by two groups of joints.

Metacarpophalangeal joints (articulationes metacarpophalangeae) are formed by the spherical heads of the metacarpal bones and the concave bases of the proximal phalanges. Their ligamentous apparatus includes ligg. collateralia, ligg. palmaria, and the deep transverse metacarpal ligament (lig. metacarpeum transversum profundum). These joints permit flexion, extension, abduction, adduction, and circumduction.

Interphalangeal joints of the hand (articulationes interphalangeae manus) are located between the phalanges themselves. Morphologically, they are typical ginglymi (hinge) joints. They are reinforced by ligg. collateralia and ligg. palmaria. Unlike the metacarpophalangeal joints, the biomechanics here are strictly limited to flexion and extension.

Mnemonic

To remember the most important movements of the thumb in the saddle joint, keep the Latin pair in mind: oppositio (opposition) and repositio (return to anatomical position).

Frequently asked questions

Which specific bones form the articular surfaces of the midcarpal joint?

The articular surfaces of the midcarpal joint are formed by the bones of the first (proximal) and second (distal) rows of the carpus, excluding the pisiform.

  • Proximal row (socket) — scaphoid (os scaphoideum), lunate (os lunatum), and triquetrum (os triquetrum).
  • Distal row (head) — trapezium (os trapezium), trapezoid (os trapezoideum), capitate (os capitatum), and hamate (os hamatum).
Which bones make up the distal row of the carpus?

The distal (second) row of the carpus consists of four short spongy bones:

  • Trapezium (os trapezium).
  • Trapezoid (os trapezoideum).
  • Capitate (os capitatum).
  • Hamate (os hamatum).

The surfaces of these bones feature articular facets for neighboring bones, and some bear palmar tubercles for muscle and ligament attachments.

With which bone does the pisiform articulate?

The pisiform bone (os pisiforme) articulates exclusively with the triquetrum (os triquetrum). This connection forms a separate, independent pisotriquetral joint (art. ossis pisiformis). The pisiform itself is a sesamoid bone that develops and resides within the tendon of the flexor carpi ulnaris (m. flexor carpi ulnaris).

Which muscles provide flexion at the radiocarpal joint?

Flexion of the hand at the radiocarpal joint is provided by the following forearm muscles:

  • Flexor carpi radialis (m. flexor carpi radialis) — performs flexion and abduction of the hand.
  • Flexor carpi ulnaris (m. flexor carpi ulnaris) — provides flexion and adduction of the hand.
  • Palmaris longus — participates in wrist flexion.

These muscles are innervated by branches of the median and ulnar nerves.

Which bones form the articular surfaces of the radiocarpal joint?

The joint is formed by the distal end of the radius, the articular disc, and three bones of the proximal carpal row: the scaphoid, lunate, and triquetrum.

Which joint of the hand has an S-shaped joint space?

An S-shaped joint space is characteristic of the midcarpal joint (articulatio mediocarpalis), located between the proximal and distal rows of carpal bones.

What is the unique feature of the thumb carpometacarpal joint?

Unlike the other planar carpometacarpal joints, the thumb joint is a saddle joint, which allows for the opposition (oppositio) of the thumb against the other fingers.

What movements are possible in the interphalangeal joints of the hand?

Because the interphalangeal joints are hinge joints, movements occur around only one axis: flexion and extension of the phalanges.

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