Short head of biceps brachii

At a glance

English

Short head of biceps brachii

Latin (TA2)

Caput breve musculi bicipitis brachii

System

Muscle

Region

Upper limb

Side

Paired, left and right

About the short head of biceps brachii

Biceps brachii has two heads, both starting on the scapula. The short head is the medial one. Its course is simpler than that of the long head because it stays outside the shoulder joint, running down the front of the arm beside coracobrachialis and in front of the brachialis.

The short head arises by a thick, flattened tendon from the tip of the coracoid process, sharing this origin with coracobrachialis. Its belly descends along the medial side of the arm and joins the long head just above the elbow. The common tendon then dips into the cubital fossa and attaches to the radial tuberosity. Fibres from the short head mostly reach the lower part of the tuberosity, those of the long head the upper part. From the medial edge of the tendon the bicipital aponeurosis spreads over the forearm flexors and blends with the deep fascia on the ulnar side.

With the long head, the short head flexes the elbow and is the strongest supinator of the forearm, most effective when the elbow is bent at a right angle. At the shoulder the short head helps flex the arm and draw it towards the body. It is supplied by the musculocutaneous nerve, which pierces coracobrachialis and then runs between biceps and brachialis. Its blood comes from muscular branches of the brachial artery.

Between the tendon and the front of the radius lies the bicipitoradial bursa, which lets the tendon glide during turning of the forearm; it can swell and press on nearby nerves. A tear of the lower tendon causes a loss of supination strength and a hollow in front of the elbow. The bicipital aponeurosis protects the brachial artery and median nerve, which pass beneath it.

Attachments, action and supply

Origin

Tip of the coracoid process of the scapula, together with coracobrachialis.

Insertion

Radial tuberosity through the common biceps tendon, and the forearm fascia through the bicipital aponeurosis.

Action

Flexes the elbow and supinates the forearm; assists flexion and adduction of the arm at the shoulder.

Nerve supply

Musculocutaneous nerve (C5, C6).

Blood supply

Muscular branches of the brachial artery.