The Bicep Brachii muscles or more commonly known just as the biceps is a two headed muscle which runs down the anterior of the Humerus from the shoulder joint down to the elbow joint. The Bicep Brachii derives it’s name from the Latin phrase when translated meaning, “two-headed muscle of the arm” due to the fact that the bicep muscle is actually two separate bundles of muscles (heads), with their own origin points that merge to form one muscle belly to share a common insertion point below the elbow joint on the upper radius. The two heads of the bicep vary in length and as a result are called the Short and the Long bicep heads.
The Short head’s origin point of attachment is the Coracoid Process. The Long head’s origin point of attachment is the Suraglenoid Tubercle. Both the Short head and the Long head merge near the middle of the humerus usually near the insertion point of the Deltoid muscle. Unusually there are two insertions for the bicep muscle because the distal bicep tendons separate into two insertion points the first being at the Radius Tuberosity on the Upper Radius and the second being at the Upper Ulnar.
The bicep muscles are chiefly responsible for the following specific movements by three different joints;
1.Supination of the Proximal Radius Joint. This forearm supination action is needed for turning a key in a door or the ignition of a car.
2.Flexion of the Humerus Joint (elbow). The bending of the elbow joint most commonly carried out during a bicep curl.
3. Glenohumeral Joint (shoulder joint). The bicep carries out several weaker functions in the shoulder joint such as assisting the forward flexion of the shoulder joint(bringing the arm forward and upwards) as well as assisting in the stabilization of the shoulder joint.
Unlike other muscles found on the front of the human body the biceps are responsible for the pulling movements as opposed to pushing movements. The bicep muscle is the antagonist to the triceps muscle and only makes up around 33 percent of muscle mass of the upper arm. There are two additional muscles that are located on the anterior of the Humerus which assist the Bicep Brachii. They are the Coracobrachialis muscle and the Brachialis muscle. These muscles lie underneath and besides the Biceps Brachii.