Muscle
Biceps brachii
Turns the forearm palm-up and bends the elbow
High-yield
Biceps combines elbow flexion with forearm supination. Its stretch reflex assesses the musculocutaneous pathway, chiefly C5–C6.
Overview
The two proximal heads begin on the scapula and share a distal attachment on the radius. Pulling on that rotating bone makes biceps a strong supinator, especially with the elbow bent.
Reference facts
- Origin
- Long head: supraglenoid tubercle and superior glenoid labrum; short head: coracoid tip
- Insertion
- Radial tuberosity, with the bicipital aponeurosis spreading into forearm fascia
- Action
- Turns the forearm palm-up and bends the elbow; also assists shoulder flexion
- Innervation
- Musculocutaneous nerve, mainly C5–C6
- Blood supply
- Muscular branches from the brachial artery
Clinical correlation
A torn long-head tendon at the shoulder may let the muscle belly gather farther down the arm, producing a visible 'Popeye' bulge. Remaining attachments and other flexors preserve some function, but weakness and pain vary.
Frequently asked questions
What does the biceps brachii do?
Turns the forearm palm-up and bends the elbow; also assists shoulder flexion.
What nerve innervates the biceps brachii?
The biceps brachii is innervated by the musculocutaneous nerve, mainly C5–C6.
Where does the biceps brachii attach?
Origin: Long head: supraglenoid tubercle and superior glenoid labrum; short head: coracoid tip. Insertion: Radial tuberosity, with the bicipital aponeurosis spreading into forearm fascia.
What is the blood supply of the biceps brachii?
The biceps brachii is supplied by the muscular branches from the brachial artery.