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 ...

bones and the proximal

phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones ...

of the fingers. These joints are of the

condyloid A condyloid joint (also called condylar, ellipsoidal, or bicondylar) is an ovoid articular surface, or condyle that is received into an elliptical cavity. This permits movement in two planes, allowing flexion, extension, adduction, abduction ...

kind, formed by the reception of the rounded heads of the

bones into shallow cavities on the proximal ends of the proximal

. 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 In the human hand, palmar or volar plates (also referred to as palmar or volar ligaments) are found in the metacarpophalangeal (MCP) and interphalangeal (IP) joints, where they reinforce the joint capsules, enhance joint stability, and limit h ...

collateral ligaments of metacarpophalangeal articulations In human anatomy, the radial (RCL) and ulnar (UCL) collateral ligaments of the metacarpophalangeal joints (MCP) of the hand A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as ...

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.

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 Extension, extend or extended may refer to: Mathematics Logic or set theory * Axiom of extensionality * Extensible cardinal * Extension (model theory) * Extension (predicate logic), the set of tuples of values that satisfy the predicate * Ext ...

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 relati ...

abduction Abduction may refer to: Media Film and television * "Abduction" (''The Outer Limits''), a 2001 television episode * " Abduction" (''Death Note'') a Japanese animation television series * " Abductions" (''Totally Spies!''), a 2002 episode of an ...

, 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 synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and ...

, as opposed to the

distal interphalangeal joint Distal interphalangeal joints are the articulations between the phalanges of the hand or foot. This term therefore includes: * Interphalangeal joints of the hand The interphalangeal joints of the hand are the hinge joints between the phalanges of ...

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 ...

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 ''quattuo ...

, 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 ...

". 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

* * {{DEFAULTSORT:Metacarpophalangeal Joint Joints