Motion
These are the joints lying between the distal heads of the metacarpals and the proximal phalanges of the digits. They are synovial condylar joints. They have a wide range of motion, including: flexion, extension, abduction and adduction. The flexion component of these is the most extensive, commonly terminated by a grasped object.
Stability
Articular capsule which blends with the ligaments.
Ligaments stabilizing the joints include:
-Palmar ligament
-2 Collateral ligaments
-Deep transverse metacarpal ligaments.
Muscles
Muscles of the MCP joint of the second to fifth digit:
Flexion:
Flexor digitorum superficialis
Flexor digitorum Profundus
Lumbricales
Interossei
Flexor digiti minimi brevis of hand
Extension:
Extensor digitorum
Extensor indicis
Extensor digiti minimi
Muscles of the MCP joint of the first metacarpal (thumb):
Flexion:
Flexor pollicis longus
Flexor pollicis brevis
Extension:
Extensor pollicis longus
Extensor pollicis brevis
Abduction:
Abductor pollicis longus
Abductor pollicis brevis
Adduction:
Adductor pollicis.
Clinical
Arthritis of MCP joints is a distinguishing feature of rheumatoid arthritis from osteoarthritis which more commonly affects the DIP joint.
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