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The posterior compartment of the forearm (or extensor compartment) contains twelve muscles which primarily extend the wrist and digits. [2] It is separated from the anterior compartment by the interosseous membrane between the radius and ulna .
Extension usually results in straightening of the bones or body surfaces involved. For example, extension is produced by extending the flexed (bent) elbow. Straightening of the arm would require extension at the elbow joint. If the head is tilted all the way back, the neck is said to be extended.
The extensor digitorum muscle (also known as extensor digitorum communis) [2] is a muscle of the posterior forearm present in humans and other animals. It extends the medial four digits of the hand. Extensor digitorum is innervated by the posterior interosseous nerve, which is a branch of the radial nerve. [3]
The extrinsic extensor muscles of the hand are located in the back of the forearm and have long tendons connecting them to bones in the hand, where they exert their action. Extrinsic denotes their location outside the hand. Extensor denotes their action which is to extend, or open flat, joints in the hand.
The extensor carpi ulnaris extends the wrist, but when acting alone inclines the hand toward the ulnar side; by its continued action it extends the elbow-joint. The muscle is a minor extensor of the carpus in carnivores, but has become a flexor in ungulates. In this case it would be described as ulnaris lateralis.
This corresponds to a counterclockwise twist for the right forearm and a clockwise twist for the left (when viewed superiorly). In the forearm, this action is performed by pronator quadratus and pronator teres muscle. Brachioradialis puts the forearm into a midpronated/supinated position from either full pronation or supination. For the foot ...
Split tendons of the muscle inserting on both ulnar and the radial side of the common extensor digitorum was also reported. [2] Anomalous hand extensors including the extensor medii proprius and the extensor indicis et medii communis are often seen as variations of the extensor indicis [2] due to the shared characteristics and embryonic origin. [8]
The common extensor tendon is the major attachment point for extensor muscles of the forearm. This enables finger extension and aids in forearm supination. Clinical significance