Muscles of the arm in 3D

Muscle groups of the upper limb

Biceps brachii and brachialis flex the elbow; coracobrachialis flexes and adducts the arm at the shoulder. All three are supplied by the musculocutaneous nerve. The posterior compartment holds triceps brachii, which extends the elbow and is supplied by the radial nerve. The deltoid caps the shoulder and abducts the arm.

In the forearm, most flexors arise from the medial epicondyle of the humerus and most extensors from the lateral epicondyle. Their long tendons cross the wrist into the hand, where the thenar and hypothenar muscles, the lumbricals and the interossei produce the fine movements of the thumb and fingers.

What the 3D model shows

The model shows the muscles of the right upper limb on its skeleton: the acromial and spinal parts of the deltoid, subscapularis and levator scapulae; the two heads of biceps, the three heads of triceps, brachialis, coracobrachialis and anconeus; the forearm flexors and extensors, including pronator teres, supinator and pronator quadratus; and the thenar, hypothenar, lumbrical and interosseous muscles of the hand. A second view adds the arteries, veins and nerves of the limb, the interosseous membrane of the forearm and the flexor retinaculum.

How to study the arm muscles

Begin in the anterior view and find biceps brachii, then hide it to reveal brachialis underneath. Switch to the posterior view for the three heads of triceps. In the forearm, name the superficial flexors from lateral to medial: pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris. Then use the muscle layers to uncover flexor digitorum superficialis and the deep layer below it. For each muscle, say its origin, insertion and action before you click it, and check the answer in the model.