Carpometacarpal Articulations

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Anatomy > Gray's Anatomy of the Human Body > III. Syndesmology > 6. Articulations of the Upper Extremity > h. Carpometacarpal Articulations

Henry Gray (1821–1865). Anatomy of the Human Body. 1918.

Carpometacarpal Articulations (Articulationes Carpometacarpeæ)

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Carpometacarpal joints of the hand (Gray's Anatomy)

The carpometacarpal (CMC) joints are the articulations between the distal row of the carpal bones and the bases of the five metacarpal bones.

They are divided into:

• The highly mobile carpometacarpal joint of the thumb (articulatio carpometacarpea pollicis)
• The four remaining carpometacarpal joints of the fingers (index to little finger), which are less mobile and are of the arthrodial type.

Carpometacarpal Joint of the Thumb

The articulation between the base of the first metacarpal bone and the trapezium (greater multangular) is a saddle joint (sellar joint), allowing for a wide range of motion.

The joint is enclosed by a thick but loose joint capsule, particularly reinforced dorsally and laterally, and lined with a synovial membrane.

Movements

Movements permitted at the first CMC joint include:

• Flexion and Extension — in the plane of the palm
• Abduction and Adduction — perpendicular to the palm
• Opposition — the most distinctive movement, bringing the thumb pad into contact with the volar surfaces of the fingers
• Circumduction — a circular motion combining the above

The movement of opposition involves a small oblique facet on the anterior part of the trapezium's articular surface. Muscular contributions include:

• Flexion: Flexor pollicis longus, Flexor pollicis brevis, Opponens pollicis, Adductor pollicis
• Extension: Abductor pollicis longus, Extensor pollicis longus, Extensor pollicis brevis
• Adduction: Adductor pollicis
• Abduction: Abductor pollicis longus, Abductor pollicis brevis, assisted by extensors

Carpometacarpal Joints of the Fingers

The CMC joints of the second through fifth metacarpals with the carpus are of the plane synovial type, allowing only limited gliding.

Ligaments

The joints are stabilized by three sets of ligaments:

• Dorsal Ligaments (Ligamenta carpometacarpea dorsalia)

These are the strongest and most distinct.

• The second metacarpal receives slips from the lesser multangular and greater multangular
• The third receives slips from the lesser multangular and capitate
• The fourth receives from the capitate and hamate
• The fifth receives a slip from the hamate, continuous with a volar ligament forming an incomplete capsule

• Volar (Palmar) Ligaments (Ligamenta carpometacarpea volaria)

Generally mirror the dorsal arrangement but may vary:

• The third metacarpal has three volar ligaments: from the trapezium, capitate, and hamate

• Interosseous Ligaments

Short and strong bands connecting the inferior angles of the capitate and hamate with the bases of the third and fourth metacarpals

Synovial Membranes

File:Gray336.png

Synovial membranes of the wrist and carpus (Gray's Anatomy)

There are generally five synovial cavities associated with the wrist and carpometacarpal region:

1. Between the ulna and the radius, lining the articular disk
2. Between the lower radius/articular disk and proximal row of carpals
3. Between proximal and distal rows of carpal bones, often continuous with the synovial membranes of the second through fifth CMC joints
4. Between the trapezium and the first metacarpal (thumb)
5. Between the pisiform bone and triquetrum

Occasionally, the fourth and fifth CMC joints have separate synovial membranes.

Movements of the Finger Carpometacarpal Joints

Only limited gliding movements occur in these joints. Their degree of mobility decreases from medial to lateral:

• Fifth metacarpal (little finger): Most mobile
• Fourth metacarpal (ring finger): Moderately mobile
• Second and third metacarpals (index and middle fingers): Almost immobile, providing a stable base for precision grip

These gliding movements contribute to grip conformation and cupping of the palm.

See Also

• Metacarpophalangeal joints
• Intercarpal joints
• Flexor retinaculum of the hand
• Carpal bones
• Hand anatomy

External Links

• Gray's s083
• NCBI: Anatomy of the Hand
• lesson4 at The Anatomy Lesson by Wesley Norman (Georgetown University)

Gray's Anatomy

• Gray's Anatomy Contents
• Gray's Anatomy Subject Index
• About Classic Gray's Anatomy
• Glossary of anatomy terms

Anatomy atlases (external)

[1] - Anatomy Atlases

Adapted from the Classic Grays Anatomy of the Human Body 1918 edition (public domain)