The metacarpophalangeal joints (MCP) are situated between the
metacarpal
In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ar ...
bones and the proximal
phalanges of the fingers.
These joints are of the
condyloid kind, formed by the reception of the rounded heads of the
metacarpal
In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ar ...
bones into shallow cavities on the proximal ends of the proximal
phalanges.
Being condyloid, they allow the movements of flexion, extension, abduction, adduction and circumduction at the joint.
Structure
Ligaments
Each joint has:
*
palmar ligaments of metacarpophalangeal articulations
*
collateral ligaments of metacarpophalangeal articulations
In human anatomy, the radial (RCL) and ulnar (UCL) collateral ligaments of the metacarpophalangeal joints (MCP) of the hand are the primary stabilisers of the MCP joints. They have two parts: the cord-like collateral ligaments proper located more ...
Dorsal surfaces
The dorsal surfaces of these joints are covered by the expansions of the Extensor tendons, together with some loose
areolar
Loose connective tissue, sometimes called areolar tissue, is a cellular connective tissue with thin and relatively sparse collagen fibers. Its ground substance occupies more volume than the fibers do. It has a viscous to gel-like consistenc ...
tissue which connects the deep surfaces of the tendons to the bones.
Function
The movements which occur in these joints are
flexion
Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...
,
extension,
adduction
Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relativ ...
,
abduction, and
circumduction; the movements of abduction and adduction are very limited, and cannot be performed while the fingers form a fist.
['' Gray's Anatomy'' (1918), see infobox]
The muscles of flexion and extension are as follows:
Clinical significance
Arthritis of the MCP is a distinguishing feature of
rheumatoid arthritis
Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and hands are invol ...
, as opposed to the
distal interphalangeal joint in
osteoarthritis
Osteoarthritis (OA) is a type of degenerative joint disease that results from breakdown of joint cartilage and underlying bone which affects 1 in 7 adults in the United States. It is believed to be the fourth leading cause of disability in the w ...
.
Other animals
In many
quadrupeds
Quadrupedalism is a form of locomotion where four limbs are used to bear weight and move around. An animal or machine that usually maintains a four-legged posture and moves using all four limbs is said to be a quadruped (from Latin ''quattuor' ...
, particularly horses and other larger animals, the metacarpophalangeal joint is referred to as the "
fetlock
Fetlock is the common name in horses, large animals, and sometimes dogs for the metacarpophalangeal and metatarsophalangeal joints (MCPJ and MTPJ).
Although it somewhat resembles the human ankle in appearance, the joint is homologous to the ba ...
". 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.
References
External links
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{{DEFAULTSORT:Metacarpophalangeal Joint
Joints