Trapezius

Innervation:

accessory n. (CNXI)

Action:

upper - elevates and upwardly rotates scapula;

middle - retracts scapula;

lower - depresses and upwardly rotates scapula

Semispinalis capitis

Innervation:

dorsal rami of cervical spinal nerves

Action:

extends neck, rotates head to opposite side

Splenius capitis and cervicis

Innervation:

dorsal rami of spinal nerves

Action:

alone - laterally bend and rotate neck to side of active muscle;

together - extend head and neck

Serratus posterior superior

Innervation:

2nd - 5th intercostal nerves

Action:

elevates ribs during inspiration

Serratus posterior inferior

Innervation:

ventral primary rami of T9-T12 spinal nerves

Action:

pulls ribs down and out during inspiration

Latissimus dorsi

Innervation:

thoracodorsal n. (C6-8)

Action:

extends, adducts, and medially rotates humerus

Levator scapulae

Innervation:

dorsal scapular n. (C5)

Action:

elevates and downwardly rotates scapula

Rhomboid major and minor

Innervation:

dorsal scapular n. (C5)

Action:

adducts, retracts, and downwardly rotates scapula

Erector spinae (spinalis, longissimus, iliocostalis)

Innervation:

dorsal rami of respective spinal nerves in each region

Action:

together - extend vertebral column;

alone - lateral flexion to the same side

Pectoralis major

Innervation:

medial (C8, T1) and lateral (C5-7) pectoral nn.

Action:

adducts and medially rotates humerus

Pectoralis minor

Innervation:

medial pectoral n. (C8, T1)

Action:

protract and depress scapula

Serratus anterior

Innervation:

long thoracic n. (C5-7)

Action:

protract and upwardly rotate scapula;

stabilize scapula on thoracic wall

Subclavius

Innervation:

subclavian n. (C5, 6)

Action:
stabilizes and depresses scapula

Biceps brachii

(long and short heads)

Innervation:

musculocutaneous n. (C5-7)

Action:

flexes forearm;

supinates forearm

Triceps brachii

(long, lateral, and medial heads)

Innervation:

radial n. (C5-8, T1)

Action:

extends forearm

Coracobrachialis

Innervation:

musculocutaneous n. (C5-7)

Action:

flexes and adducts arm

Deltoid

Innervation:

axillary n. (C5,6)

Action:

anterior fibers - flex humerus;

middle fibers - abduct humerus;

posterior fibers - extend humerus

Teres major

Innervation:

lower sub scapular n. (C5,6)

Action:

medially rotates and adducts humerus

Teres minor

Innervation:

axillary n. (C5,6)

Action:

stabilizes shoulder joint (rotator cuff muscle);

laterally rotates humerus

Infraspinatus

Innervation:

suprascapular n. (C5,6)

Action:

stabilizes shoulder joint (rotator cuff muscle);

laterally rotates humerus

Supraspinatus

Innervation:

suprascapular n. (C5,6)

Action:

stabilizes shoulder joint (rotator cuff muscle);

abducts humerus

Subscapularis

Innervation:

upper (C5,6) and lower (C5,6) subscapular nn.

Action:

stabilizes shoulder joint (rotator cuff muscle);

medially rotates humerus

Subscapularis

Innervation:

upper (C5,6) and lower (C5,6) subscapular nn.

Action:

stabilizes shoulder joint (rotator cuff muscle);

medially rotates humerus

Brachialis

Innervation:

musculocutaneous n. (C5-7)

Action:

flexes forearm

Anconeous

Innervation:

radial n. (C5-8, T1)

Action:

extends forearm

Brachioradialis

Innervation:

radial n. (C5-8, T1)

Action:

flexes forearm

Supinator

Innervation:

radial n. (C5-8, T1)

Action:

supinates forearm

Pronator teres

Innervation:

median n. (C6-8, T1)

Action:

pronates and flexes forearm

Flexor carpi radialis

Innervation:

median n. (C6-8, T1)

Action:

flexes hand;

adducts wrist

Palmaris longus

Innervation:

median n. (C6-8, T1)

Action:

flexes wrist;

tightens palmar aponeurosis

Flexor digitorum superficialis

Innervation:

median n. (C6-8, T1)

Action:

flexes PIP;

assists in MCP flexion

Flexor digitorum profundus

Innervation:

medial part - ulnar n. (C8, T1);

lateral part - median n. (C6-8, T1)

Action:

flexes DIP of digits

Flexor pollicis longus

Innervation:

median n. (C6-8, T1)

Action:

flexes IP of thumb

Pronator quadratus

Innervation:

median n. (C6-8, T1)

Action:

pronates forearm

Flexor carpi ulnaris

Innervation:

ulnar n. (C8, T1)

Action:

flexes and adducts wrist

Palmaris brevis

Innervation:

ulnar n. (C8, T1)

Action:

tightens and corrugates skin over palm to improve grip

Abductor pollicis brevis

Innervation:

recurrent branch of median n.

Action:

abducts thumb at CMC;

assists in opposition

Flexor pollicis brevis

Innervation:

recurrent branch of median n.

Action:

flexes thumb at IP joint

Opponens pollicis

Innervation:

recurrent branch of median n.

Action:

opposes thumb;

rotates thumb medially

Abductor digiti minimi

Innervation:

ulnar n. (C8, T1)

Action:

abducts 5th digit (little finger)

Flexor digiti minimi brevis

Innervation:

ulnar n. (C8, T1)

Action:

flexes MCP of 5th digit (little finger)

Extensor carpi ulnaris

Innervation:

radial n. (C5-8, T1)

Action:

flexes and adducts wrist

Extensor digitorum

Innervation:

radial n. (C5-8, T1)

Action:

extends MCP joints of digits;

assists in extension of IP joints

Extensor digiti minimi

Innervation:

radial n. (C5-8, T1)

Action:

extends MCP joint of 5th digit (little finger);

assists in extension of IP joints

Extensor carpi radialis brevis

Innervation:

radial n. (C5-8, T1)

Action:

extends wrist

Extensor carpi radialis longus

Innervation:

radial n. (C5-8, T1)

Action:

extends and abducts (radially deviates) hand at wrist

Abductor pollicis longus

Innervation:

radial n. (C5-8, T1)

Action:

abducts thumb at CMC joint

Extensor pollicis longus

Innervation:

radial n. (C5-8, T1)

Action:

extends IP joint of thumb

Extensor indicis

Innervation:

radial n. (C5-8, T1)

Action:

extends 2nd digit (index finger) at MCP

Extensor pollicis brevis

Innervation:

radial n. (C5-8, T1)

Action:

extends MCP and CMC joints of thumb

Adductor pollicis

Innervation:

ulnar n. (C8, T1)

Action:

adducts thumb towards middle digit at CMC joint

Dorsal interossei

1-4

Innervation:

ulnar n. (C8, T1)

Action:

abduct digits from axial line;

assists in flexing MCP and extending IP joints of digits

Opponens digiti minimi

Innervation:

ulnar n. (C8, T1)

Action:

opposes 5th digit (little finger) to thumb

Palmar interossei:

1-3

Innervation:

ulnar n. (C8, T1)

Action:

adducts digits towards axial line;

assists in flexing MCP joints and extending IP joints

Lumbricals 1 & 2

Innervation:

median n. (C6-8, T1)

Action:

flexes MCP joints;

extends IP joints

Lumbricals 3 & 4

Innervation:

ulnar n. (C8, T1)

Action:

flexes MCP joints;

extends IP joints