Motion of flexion and extension of the elbow joint
MOTION OF FLEXION AND EXTENSION OF THE ELBOW JOINT ANATOMYThe motion of flexion and extension of the elbow joint is directed by the muscles of the brachium. The powerful muscles of this group include the biceps brachii, the brachioradialis, the brachialis, and the triceps brachii. Just along the rim of the elbow joint, over the distal portion of the triceps brachii, there lies and additional muscle bearing the shape of a triangle. This short muscle is known as the anconeus.
MOTION OF FLEXION AND EXTENSION OF THE ELBOW JOINT STRUCTUREAlong the anterior surface of the humerus bone rests the bicaeps brachii. This powerhouse of a muscle is one of the easiest to identify and is often recognized even by lay individuals. Despite this fact, the humerus and the biceps brachii have no existing attachment to each other. The biceps brachii is one of the few unique muscles in the human body with a dual origin.
The short head, which is also known as the medial tendonous head, originates from the coracoid process of the scapula. The second head, the long head, originates from the superior tuberosity of the glenoid cavity. From there, it can be traced directly through the shoulder joint and then down the intertubercular groove of the humerus. The biceps brachii is only allotted one insertion point, however, along the radial tuberosity.
MOTION OF FLEXION AND EXTENSION OF THE ELBOW JOINT DIAGRAM
Image: Muscles The Elbow Joint
The most obvious and easily discernable muscle of the forearm, which runs along the radial side, is the brachioradialis. This muscle is also responsible for the flexing of the elbow joint.
MOTION OF FLEXION AND EXTENSION OF THE ELBOW JOINT FACTSAlong the posterior region of the brachium one can locate the triceps brachii, which is responsible for creating opposing contractions against the biceps brachii leading to extension of the elbow joint. This antagonist relationship between these two muscles allows for complete movement of the elbow. The triceps is unique with its advantageous triple origins.
The later and medial origins arise from the humerus, and are shorter than the third head. The elongated head originates infraglenoid tuberosity of the scapula. The triceps brachii can then be traced to its insertion point along the olecranon of the ulna, which is secured via a common tendon. Elbow extensions are ultimately achieved through the synergistic relationship between the triceps brachii and the small anconeus muscle.