Muscle of the Arm and Forearm dorsal/posterior The Muscular System

Muscles of the Upper Limb 3 groups Muscles that arise from the shoulder girdle and cross the shoulder joint to insert into the humerus Muscles that cause movement at the elbow which insert on the forearm bones Muscles of the forearm which insert on the hand bones

General Organization Upper Limb Extensors on the posterior/dorsal surface

Muscles that act on the wrist Generally originate on the distal humerus Extensors on the lateral epicondyle Insert on the carpals and metacarpals

Muscles that act on the fingers Generally originate on the distal humerus Extensors on the lateral epicondyle Insert on the phalanges

Clavobrachialis (Clavodeltoid): Deltoid muscle in humans Action: Abducts the shoulder Origin: Clavicle and scapula Insertion: Deltoid tuberosity of humerus May elevate, adduct, depress or rotate scapula and/or elevate clavicle; can also extend or hyperextend the neck

Triceps brachii Action: antagonist of biceps Origin: three heads Extension (shoulder and elbow) Origin: three heads Shoulder girdle and proximal humerus Insertion: Olecranon process of ulna

Brachioradialis: Action: Flexion at the elbow Origin: lateral epicondyle of the humerus Insertion: Styloid process of the radius

Extensor carpi radialis Action: Extension/abduction (wrist) Origin: Lateral epicondyle Insertion: Second and third metacarpals

Extensor digitorum Action: Origin: Insertion: Extension (fingers and wrist) Origin: Lateral epicondyle Insertion: Posterior surfaces of phalanges

Extensor carpi ulnaris Action: Extension/adduction (wrist) Origin: Lateral epicondyle Insertion: Base of 5th metacarpal

Dorsal Surface clavobrachialis Extensor digitorum Extensor carpi radialis brachioradialis Extensor carpi ulnaris Triceps brachii

Posterior/dorsal Triceps brachii brachioradialis

Posterior/dorsal Triceps brachii brachioradialis Extensor carpi radialis Extensor carpi ulnaris Flexor carpi ulnaris

Posterior/dorsal Triceps brachii brachioradialis Extensor carpi radialis Extensor carpi ulnaris Flexor carpi ulnaris Extensor digitorum