Biceps brachii

The biceps brachii (Latin: musculus biceps brachii) is a sizable two-headed muscle of the upper limb. It is located in the anterior compartment of the upper arm together with the brachialis and coracobrachialis muscles. The biceps brachii stretches between the scapula and radius and acts at the shoulder and elbow joints. It is the most prominent and essential muscle of the anterior upper arm. The biceps brachii is composed of two heads, named the long and short heads.

Origin

The long head of the biceps brachii originates from the supraglenoid tubercle of the scapula, while the short head arises from the coracoid process of the scapula.

Insertion

Fibers of both heads merge at the anterior middle aspect of the humerus and insert on the radial tuberosity of the radius. The bicipital aponeurosis - connective tissue membrane - arises from the distal portion of the muscle and inserts into the deep fascia of the forearm.

Action

The primary functions of the biceps brachii muscle are flexion and supination of the forearm at the elbow joint. Fibers of the short head provide flexion of the arm, while fibers of the long head are responsible for abduction of the arm.

Innervation

The biceps brachii is innervated by the musculocutaneous nerve (C5 - C6) that is a branch of the brachial plexus.

Blood supply

The biceps brachii muscle receives arterial blood supply from various branches of the brachial artery.