Anatomy Muscles - Origin, Insertion, Action

frontalis

draws scalp forward, raises eyebrows

occipitalis

retracts scalp

orbicularis oris

compresses and purses lips (kiss muscle)

orbicularis oculi

closes eye

platysma

pulls lower lip inferiorly, tenses skin of neck, aids in depressing mandible

zygomaticus major

pulls corners of mouth superiorly (smiling muscle)

zygomaticus minor

raises upper lip, exposing upper teeth

buccinator

presses cheek against molar teeth, holds food between teeth during chewing

temporalis

O: parietal and frontal bones

I: coronoid process of the mandible

A: elevates and retracts mandible at jaw

masseter

O: zygomatic arch

I: coronoid process, angle, and ramus of mandible

A: closes jaw; elevates mandible at jaw

sternocleidomastoid

O: manubrium of the sternum, sternal end of the clavicle

I: mastoid process of the temporal bone

A: laterally flexes and rotates head to the opposite side of contracting muscle (one side); flexes cervical portion of vertebral column (both sides)

splenius capitis

O: ligamentum nuchae

I: occipital bone, mastoid process of the temporal bone

A: rotate head to same side of contracting muscle (one side); extend head and neck (both sides)

splenius cervicis

O: spinous processes T3 - T6

I: transverse processes of cervical vertebrae

A: rotate head to the same side of contracting muscle (one side); extend head and neck (both sides)

trapezius

superior fibers: elevate and upwardly rotate scapula; elevate clavicle; extend head

middle fibers: adduct scapula

inferior fibers: depress scapula

levator scapulae

elevates scapula

rhomboid major

stabilizes, elevates, and adducts scapula

rhomboid minor

stabilizes, elevates, and adducts scapula

serratus anterior

abducts and stabilizes scapula

pectoralis minor

abducts and depresses scapula

supraspinatus

O: supraspinous fossa of scapula

I: greater tubercle of humerus

A: abducts arm

infraspinatus

O: infraspinous fossa of scapula

I: greater tubercle of humerus

A: laterally rotates arm

teres minor

O: lateral border of scapula

I: greater tubercle of humerus

A: laterally rotates and weakly adducts arm

subscapularis

O: subscapular fossa of scapula

I: lesser tubercle of humerus

A: medially rotates arm

teres major

O: lateral border and angle of scapula

I: lesser tubercle and intertubercular sulcus of humerus

A: extends, adducts, and medially rotates arm

latissimus dorsi

O: spinous processes of lower thoracic vertebrae, lower ribs (8-12), iliac crest of ilium

I: intertubercular sulcus of humerus

A: extends, adducts, and medially rotates arm

deltoid

O: acromial end of clavicle, acromion and spine of scapula

I: deltoid tuberosity of humerus

A: abducts, flexes, and extends arm

pectoralis major

O: clavicle, costal cartilages

I: intertubercular sulcus of humerus

A: flexes, adducts, and medially rotates arm

triceps brachii (long head)

O: infraglenoid tubercle of scapula

I: olecranon process of ulna

A: extends forearm

triceps brachii (lateral head)

O: posterior shaft of humerus

I: olecranon process of ulna

A: extends forearm

triceps brachii (medial head)

O: distal 2/3 of posterior shaft of humerus

I: olecranon process of ulna

A: extends forearm

anconeus

extends forearm

biceps brachii (long head)

O: supraglenoid tubercle of scapula

I: radial tuberosity of radius

A: supinates forearm at radioulnar joint

biceps brachii (short head)

O: coracoid process of scapula

I: radial tuberosity of radius

A: supinates forearm at radioulnar joint

coracobrachialis

O: coracoid process of scapula

I: middle medial shaft of humerus

A: adducts and flexes arm

brachialis

O: distal, anterior surface of humerus

I: coronoid process of ulna

A: flexes forearm

brachioradialis

O: lateral distal humerus

I: styloid process of radius

A: flexes forearm

pronator teres

pronates forearm at radioulnar joint

flexor carpi radialis

flexes and abducts hand

palmaris longus

weakly flexes hand

flexor carpi ulnaris

flexes and adducts hand

flexor digitorum superficialis

flexes hand

flexor digitorum profundus

flexes hand

flexor pollicis longus

flexes distal phalanx thumb at IP joint

flexor retinaculum

fibrous band of connective tissue that covers the palmar surface of the carpal bones

extensor carpi radialis longus

extends and abducts hand

extensor carpi radialis brevis

extends and abducts hand

extensor digitorum

extends hand

extensor carpi ulnaris

extends and adducts hand

abductor pollicis longus

weakly extends hand

extensor pollicis brevis

weakly extends hand

extensor pollicis longus

weakly extends hand

supinator

supinates forearm at radioulnar joint

extensor retinaculum

fibrous band of connective tissue that covers the dorsal surface of the carpal bones