Biceps Brachii
The biceps brachii is a two-headed muscle located on the anterior compartment of the upper arm. It is one of the most recognizable muscles in the human body and plays a crucial role in forearm supination and elbow flexion.
Origin, Insertion, Action, Innervation
OOrigin
Long head: Supraglenoid tubercle of scapula. Short head: Coracoid process of scapula.
IInsertion
Radial tuberosity and bicipital aponeurosis into deep fascia of forearm.
AAction
- • Flexion of the elbow joint
- • Supination of the forearm (most powerful supinator when elbow is flexed)
- • Weak flexion of the shoulder joint
- • Stabilization of the shoulder joint
NInnervation
Musculocutaneous nerve (C5, C6)
Blood Supply
Brachial artery via muscular branches
Clinical Relevance
Biceps tendon rupture can occur at the proximal (shoulder) or distal (elbow) attachment. Distal ruptures cause a 'Popeye' deformity. The biceps reflex tests the C5-C6 nerve roots and musculocutaneous nerve integrity.
Palpation
Easily palpated on the anterior arm. Have the patient flex the elbow against resistance with the forearm supinated to make the muscle prominent.
Study Tips
- ✓Remember 'BIS' - Biceps Is Supinator (strongest when elbow flexed)
- ✓Two heads = two origins, one insertion
- ✓Musculocutaneous nerve = C5, C6 (Biceps, Brachialis, Coracobrachialis)
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Common questions about the biceps brachii
The biceps brachii has two heads with different origins. The long head originates from the supraglenoid tubercle of the scapula, while the short head originates from the coracoid process of the scapula.
The biceps brachii has two main actions: flexion of the elbow and supination of the forearm. It is the most powerful supinator when the elbow is flexed at 90 degrees.
The biceps brachii is innervated by the musculocutaneous nerve, which carries fibers from the C5 and C6 nerve roots.
A biceps tendon rupture is a tear of the biceps tendon, most commonly at the distal attachment near the elbow. It causes weakness in supination and flexion, and may produce a visible 'Popeye' deformity as the muscle belly retracts.