Muscles of the upper extremity: Action and innervation

Pectoralis major

Actions (5): Shoulder flexion, IR, horizontal adduction. Scapular protraction and depression.

Innervation: Lateral pectoral nerve

5 actions

Pectoralis minor

Actions (3): Scapular protraction, depression, downward rotation.

Innervation: Medial pectoral nerve

3 actions

Serratus anterior

Actions (3): Scapular protraction, depression, upward rotation

Innervation: Long thoracic nerve

3 actions

Trapezius

Actions (4): Upper fibers - scapular elevation, middle fibers - scapular retraction, lower fibers - scapular depression, upper and lower fibers - upward rotation of scapula

Innervation: Spinal accessory nerve (CN XI)

4 actions (1 for each section of traps + 1 for upper and lower fibers combined)

Rhomboid major and minor

Actions (3): Adduction, elevation and downward rotation of scapula

Innervation: Dorsal scapular nerve

3 actions

Levator scapulae

Actions (2): Scapular elevation and downward rotation

Innervation: Ventral rami of spinal nerves C3-C4 and the dorsal scapular nerve

2 actions

Sternocleidomastoid (SCM)

Actions (2): Ipsilateral neck flexion, contralateral neck rotation

Innervation: Spinal accessory nerve (CN XI)

2 actions

Latissimus dorsi

Actions (3): Shoulder IR, adduction and extension

Innervation: Thoracodorsal nerve

3 actions

Deltoid

Actions (3): Shoulder abduction, flexion (anterior fibers), extension (posterior fibers)

Innervation: Axillary nerve

3 actions

Teres major

Actions (3): Shoulder IR, extension, adduction

Innervation: Lower subscapular nerve

3 actions

Coracobrachialis

Actions (1): Shoulder flexion

Innervation: Musculocutaneous nerve

1 action

Subscapularis

Actions (2): Shoulder IR and adduction

Innervation: Upper and lower subscapular nerves

2 actions

Supraspinatus

Actions (1): First 15 deg of shoulder abduction

Innervation: Suprascapular nerve

1 action

Infraspinatus

Actions (1): Shoulder ER

Innervation: Suprascapular nerve

1 action

Teres minor

Actions (1): Shoulder ER

Innervation: Axillary nerve

1 action

Biceps brachii

Actions (3): Elbow flexion and supination, shoulder flexion

Innervation: Musculocutaneous nerve

3 actions

Brachialis

Actions (1): Elbow flexion

Innervation: Musculocutaneous nerve

1 action

Triceps brachii

Actions (2): Elbow extension, shoulder extension

Innervation: Radial nerve

2 actions

Brachioradialis

Actions (1): Elbow flexion in neutral hand grip position

Innervation: Radial nerve

1 action

Anconeus

Actions (1): Elbow extension (weak)

Innervation: Radial nerve

1 action