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Portrait of Biceps brachii

Anatomy · Muscles

Biceps brachii

Two-headed muscle of the front of the arm

Upper limb · arm, anterior compartment

Biceps brachii is the two-headed muscle on the front of the upper arm. Its long head arises from the supraglenoid tubercle and its short head from the coracoid process; both join a tendon that inserts on the radial tuberosity. It flexes the elbow and, above all, supinates the forearm, and is supplied by the musculocutaneous nerve.

How to spot them

  • ▸Spindle-shaped muscle bulging on the front of the arm, the classic flexed-arm muscle
  • ▸Two heads at the shoulder, one arising from the scapula's coracoid process and one from just above the glenoid
  • ▸Tendon crosses the elbow to reach the radius, not the ulna
  • ▸Lies over the brachialis, which is the deeper elbow flexor

What to know

A muscle with two origins at the shoulder, one of them a tendon that runs inside the shoulder joint and out through the intertubercular groove

Biceps brachii — the long head.

The muscle that turns the palm upward, most powerfully when the elbow is bent, as in driving a corkscrew

Biceps brachii — the strongest supinator of the forearm.

A tendon that inserts on the rough tuberosity of the radius, with an expansion blending into the fascia of the forearm

Biceps brachii — radial tuberosity and bicipital aponeurosis.

A muscle supplied by the musculocutaneous nerve, tested by a tendon tap at the crook of the elbow (C5–C6)

Biceps brachii — the biceps reflex.

A muscle whose shorter head arises from the tip of the coracoid process together with coracobrachialis

Biceps brachii — the short head.

The muscle popularly associated with a strongman's flexed arm

Biceps brachii.

Key ideas

  • It crosses both shoulder and elbow, so it is a weak flexor of the shoulder as well as a strong flexor and supinator of the forearm.
  • At the elbow it works best with the forearm supinated; brachialis flexes regardless of forearm position.

Quick-fire facts

  • •Origin: long head from the supraglenoid tubercle of the scapula, short head from the coracoid process.
  • •Insertion: radial tuberosity, plus the bicipital aponeurosis (lacertus fibrosus) into the deep fascia of the forearm.
  • •Nerve supply: musculocutaneous nerve (C5–C6).
  • •Actions: flexes the elbow, supinates the forearm, and weakly flexes the shoulder.
  • •The long head's tendon lies inside the capsule of the shoulder joint, in the intertubercular groove; it can rupture, giving the 'Popeye' bulge.
  • •Biceps means 'two-headed'; brachii means 'of the arm'.
  • •The biceps reflex is tested by tapping the biceps tendon and tests the C5–C6 segments.

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Sources