The metacarpophalangeal (MCP) joints are diarthrodial joints where the large convex heads of the distal aspect of the metacarpals articulate with the concave-shaped proximal aspect of each phalange. The articulating surface of each metacarpal head and proximal phalange is composed of hyaline cartilage.
What are metacarpophalangeal joints formed by?
The metacarpophalangeal joints (MCP) are situated between the metacarpal 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 bones into shallow cavities on the proximal ends of the proximal phalanges.
What type of synovial joints are the metacarpophalangeal joints of the hand?
Metacarpophalangeal (MCP) joints
| Type | Synovial, condyloid joint |
|---|---|
| Articular surfaces | Heads of the distal aspect of the metacarpal bones Proximal aspects of the phalanges |
| Ligaments | Collateral ligament, palmar ligament, deep transverse metacarpal ligaments |
What are MCP and IP joints?
Metacarpophalangeal ligaments and interphalangeal ligaments. The fingers (index through small fingers) are composed of 3 bones each and are all associated with a single metacarpal. Thus, 3 joints per finger exist, all of which have significant motion and require stabilization to prevent subluxation and dislocation.
Are metacarpophalangeal joints hinge joints?
The thumb MCP joint is a multiaxial diarthodial hinge joint able to flex, extend, abduct, adduct, and circumduct. There are static and dynamic stabilizers of the thumb MCP joint. The main static stabilizers are the radial and ulnar collateral ligaments, as well as the accessory collateral ligament.
What types of movements are possible in the metacarpophalangeal joints?
—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 when the fingers are flexed.
What muscles abduct the metacarpophalangeal joints?
The dorsal interosseous muscles function primarily in MP joint abduction. The abductor pollicis brevis and abductor digiti minimi muscles perform similar functions at the thumb and pinky respectively. The palmar interosseous muscles perform adduction of the MP joint to close spread fingers.
Is the metacarpophalangeal joint a saddle joint?
The first CMC joint is a saddle-shaped, very mobile articulation between the trapezium and the base of the first metacarpal. It allows 40° to 50° of thumb flexion–extension parallel to the plane of the palm and 40° to 70° of adduction–abduction perpendicular to the plane of the palm.
What flexes the metacarpophalangeal joint?
The flexors are the flexor pollicis brevis, lumbricals, interossei, and flexor digiti minimi brevis, assisted by the long flexors. Radial and ulnar movements at the second to fifth MCP joints are a function of the intrinsic muscles.
Where is the first metacarpophalangeal joint?
The 1st CMC (carpometacarpal) joint is a specialized saddle-shaped joint at the base of the thumb. The trapezium carpal bone of the wrist and the first metacarpal bone of the hand form the 1st CMC or thumb basal joint.
