Long Head of Biceps Brachii

Origin

The long head of biceps brachii muscle originates, via a long cylindrical tendon, from the supraglenoid tubercle of the scapula. This origin site is located within the capsule of the glenohumeral (shoulder) joint, and its tendon is continuous with the glenoid labrum of the glenohumeral joint.

Insertion

The muscle bellies of the long and short heads of biceps brachii travel inferiorly and converge to a single biceps brachii tendon, which inserts onto the radial tuberosity of radius. This tendon gives off a flat tendinous expansion, known as the bicipital aponeurosis, which travels inferomedially to attach to the antebrachial fascia.

Key Features & Anatomical Relations

The biceps brachii muscle is found in the anterior compartment of the arm. It is a fusiform type of skeletal muscle and is composed of two heads:

- laterally located long head;

- medially located short head.

In some individuals, there is a third head of biceps brachii muscle, which arises from the brachialis muscle and attaches to the medial side of the tendon of biceps brachii and the bicipital aponeurosis.

The biceps brachii muscle is located:

- anterior (superficial) to the brachialis muscle and the musculocutaneous nerve;

- posterior (deep) to the brachial fascia and the pectoralis major muscle;

- medial to the cephalic vein;

- lateral to the coracobrachialis muscle, brachial artery, basilic vein, and the median nerve.

Regarding the long head of biceps brachii specifically, it travels laterally, from its origin site, through the glenohumeral (shoulder) joint whilst being enclosed in a synovial sheath. It then curves in an inferolateral direction, over the head of the humerus, and travels inferiorly along the intertubercular sulcus. It is held in the sulcus by the transverse humeral ligament.

Actions & Testing

The biceps brachii muscle is involved in multiple actions:

- supinates the forearm at the radioulnar joints;

- flexes the forearm at the elbow joint, most strongly when the forearm is in the supinated position;

- assists in flexion of the arm at the glenohumeral (shoulder) joint.

The biceps brachii muscle can be tested by placing the forearm in the supinated position and flexing the forearm at the elbow joint against resistance, during which it can be palpated (Standring, 2016).

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.