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The index metacarpal is the most firmly fixed, while the thumb metacarpal articulates with the trapezium and acts independently from the others. The middle metacarpals are tightly united to the carpus by intrinsic interlocking bone elements at their bases. The ring metacarpal is somewhat more mobile while the fifth metacarpal is semi ...
The extrinsic muscle groups are the long flexors and extensors. They are called extrinsic because the muscle belly is located on the forearm. The intrinsic group are the smaller muscles located within the hand itself. The muscles of the hand are innervated by the radial, median, and ulnar nerves from the brachial plexus. [1]
The muscles can be compared to guy-wires supporting a flagpole; tension from these muscular guy-wires must be provided in all directions to maintain stability in the articulated column formed by the bones of the thumb. Because this stability is actively maintained by muscles rather than by articular constraints, most muscles attached to the ...
It opposes the thumb and assists in adduction. It is innervated by the median nerve. [29] Other muscles involved are: The adductor pollicis also has two heads. The transversal head originates along the entire third metacarpal bone, while the oblique head originates on the carpal bones proximal to the third metacarpal.
They are specified as 'dorsal' to contrast them with the palmar interossei, which are located on the anterior side of the metacarpals. The dorsal interosseous muscles are bipennate, with each muscle arising by two heads from the adjacent sides of the metacarpal bones, but more extensively from the metacarpal bone of the finger into which the ...
This muscle originates from the medial epicondyle of the humerus as part of the common flexor tendon. It runs just laterally of flexor digitorum superficialis and inserts on the anterior aspect of the base of the second metacarpal, and has small slips to both the third metacarpal and trapezium tuberosity. [1]
The extensor carpi radialis longus is one of the five main muscles that control movements at the wrist. [1] This muscle is quite long, starting on the lateral side of the humerus, and attaching to the base of the second metacarpal bone (metacarpal of the index finger).
Interosseous muscles of the hand; Details; Origin: Dorsal: metacarpal bones 1 to 5. Palmar: metacarpal bones of digits 2, 4, 5: Insertion: Dorsal: bases of proximal phalanges and extensor expansions of digits 2 to 4. Palmar: base of proximal phalanx and extensor expansion of the same digit from which it originated. Nerve: deep branch of the ...