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The relative length of the digit varies during motion of the IP joints. The length of the palmar aspect decreases during flexion while the dorsal aspect increases by about 24 mm. The useful range of motion of the PIP joint is 30–70°, increasing from the index finger to the little finger.
In the human hand, palmar or volar plates (also referred to as palmar or volar ligaments) [1] are found in the metacarpophalangeal (MCP) and interphalangeal (IP) joints, where they reinforce the joint capsules, enhance joint stability, and limit hyperextension.
The collateral ligaments of interphalangeal joints are ligaments of the interphalangeal joints of the hand. They limit extension at these joints (together with the palmar ligaments). [1] On each side of the interphalangeal joints of the fingers are diagonally placed fibrous bands. The proximal ends of the bands are near the dorsal phalanges of ...
A hand imitating an ulnar claw. The metacarpophalangeal joints of the 4th and 5th fingers are extended and the Interphalangeal joints of the same fingers are flexed.. An ulnar claw, also known as claw hand or Spinster’s Claw, is a deformity or an abnormal attitude of the hand that develops due to ulnar nerve damage causing paralysis of the lumbricals.
Anatomically, it is said that the knuckles consist of the metacarpophalangeal [1] (MCP) and interphalangeal (IP) joints of the finger. The knuckles at the base of the fingers may be referred to as the 1st [1] or major knuckles while the knuckles at the midfinger are known as the 2nd [2] and 3rd, or minor, knuckles.
The muscle is inserted onto the radial sesamoid bone of the metacarpophalangeal joint. It acts to flex, adduct, and abduct the thumb, and is therefore also able to oppose the thumb. The superficial head is innervated by the median nerve , while the deep head is innervated by the ulnar nerve (C8-T1). [ 6 ]
They are seen in osteoarthritis, where they are caused by the formation of calcific spurs of the articular (joint) cartilage. Much less commonly, they may be seen in rheumatoid arthritis, where nodes are caused by antibody deposition to the synovium. A Bouchard's node on the proximal interphalangeal joint of the index finger of a 64 year old man.
It tends to separate the fingers as it extends them. In the fingers, the extensor digitorum acts principally on the proximal phalanges, acting to extend the metacarpophalangeal joint. Extension of the proximal and distal interphalangeal joints, however, is mediated predominantly by the dorsal and palmar interossei and lumbricals of the hand.