Metacarpophalangeal joint

Metacarpophalangeal joint

The palmar aspect of the hand showing the epiphyses of the hand exploded. MCP joints in red.

Metacarpophalangeal articulation and articulations of digit. Palmar aspect.
System 099
Latin articulationes metacarpophalangeae
MeSH A02.835.583.345.512
TA A03.5.11.501
FMA 71364

Anatomical terminology

The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the phalanges of the fingers. That means the MCP joint is the knuckle between the hand and the finger. These are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the first phalanges, with the exception of that of the thumb, which is a saddle joint.



Metacarpophalangeal articulation and articulations of digit. Ulnar aspect.
See also: Palmar plate

Each joint has:

Dorsal surfaces

The dorsal surfaces of these joints are covered by the expansions of the Extensor tendons, together with some loose areolar tissue which connects the deep surfaces of the tendons to the bones.


The movements which occur in these joints are flexion, extension, adduction, abduction, and circumduction; the movements of abduction and adduction are very limited, and cannot be performed while the fingers form a fist.[1]

The muscles of flexion and extension are as follows:

Location Flexion Extension
fingers Flexor digitorum superficialis and profundus, lumbricales, and interossei, assisted in the case of the little finger by the flexor digiti minimi brevis extensor digitorum communis, extensor indicis proprius, and extensor digiti minimi muscle
thumb flexor pollicis longus and brevis extensor pollicis longus and brevis

Clinical significance

Arthritis of the MCP is a distinguishing feature of Rheumatoid Arthritis, as opposed to the distal interphalangeal joint in osteoarthritis.

Other animals

In many quadrupeds, particularly horses and other larger animals, the metacarpophalangeal joint is referred to as the "fetlock." This term is translated literally as "foot-lock." In fact, although the term fetlock does not specifically apply to other species' metacarpophalangeal joints (for instance, humans), the "second" or "mid-finger" knuckle of the human hand does anatomically correspond to the fetlock on larger quadrupeds. For lack of a better term, the shortened name may seem more practical.


This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

  1. Gray's Anatomy (1918), see infobox
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