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Pivot joint. In animal anatomy, a pivot joint (trochoid joint, rotary joint or lateral ginglymus) is a type of synovial joint whose movement axis is parallel to the long axis of the proximal bone, which typically has a convex articular surface. According to one classification system, a pivot joint like the other synovial joint —the hinge ...
The musculocutaneous nerve is a mixed branch of the lateral cord of the brachial plexus derived from cervical spinal nerves C5-C7. It arises opposite the lower border of the pectoralis major. It provides motor innervation to the muscles of the anterior compartment of the arm: the coracobrachialis, biceps brachii, and brachialis. [ 1 ]
Dorsal rotation injury, such as when a drill binds and rotates the wrist instead of the bit, can also cause traumatic injuries. Injury may also occur from a distraction force applied to the volar forearm or wrist. Finally, tears of the TFCC are frequently found by patients with distal radius fractures. [7]
The flexor carpi radialis is one of four muscles in the superficial layer of the anterior compartment of the forearm. 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 ...
The pronator teres is a muscle (located mainly in the forearm) that, along with the Pronator quadratus muscle pronator quadratus, serves to pronate the forearm (turning it so that the palm faces posteriorly when from the anatomical position). It has two origins, at the medial humeral supracondylar ridge and the medial side of the coronoid ...
Supinator always acts together with biceps, except when the elbow joint is extended. [7] It is the most active muscle in forearm supination during unresisted supination, while biceps becomes increasingly active with heavy loading. [8] Supination strength decreases by 64% if supinator is disabled by, for example, injury.
Erb's palsy is a paralysis of the arm caused by injury to the upper group of the arm's main nerves, specifically the severing of the upper trunk C5–C6 nerves. These form part of the brachial plexus, comprising the ventral rami of spinal nerves C5–C8 and thoracic nerve T1. [1][2][3] These injuries arise most commonly, but not exclusively ...
The driver extends their right arm with the forearm pointing vertically downwards and moving in a circular anti-clockwise motion. Drivers of tractors, animal-drawn vehicles and two-wheeled vehicles may also extend their left arm horizontally with the palm facing forwards. Signal lights or turn indicators may be used in place of hand signals if ...