Muscles of the body

Frontalis

raises eyebrows

Zygomaticus

raises corners of the mouth

Masseter

chewing

Temporalis

elevates and retracts mandible

Sternocleidomastoid

rotates and flexes neck, there are two, one on each side; when both are flexed, head is bent toward chest and when one is flexed, head rotates; sometimes called “prayer muscle”

External oblique

fibers run down toward midline

Origin of external oblique

outer surfaces of lower 8 ribs

Insertion of external oblique

lina alba

Action of of external oblique

flex vertebral column, rotation if one side

Internal oblique

fibers run up toward midline

Origin of internal oblique

lumbar fascia, iliac crest, inguinal ligament

Insertion of internal oblique

linea alba, pubic crest

Action of internal oblique

flex vertebral column, rotation if one side

Transversus abdominis

fibers run across

Origin of transversus abdominals

inguinal ligament, lumbar fascia, ribs, iliac crest

Insertion of transversus abdominals

linea alba, pubic crest

Action of transversus abdominals

compress abdomen

Rectus abdominis

fibers run up and down

Origin of rectus abdominis

pubic crest and symphysis

Insertion of rectus abdominis

xiphoid process and costal cartilages of ribs 5-7

Action of rectus abdominis

flex and rotate lumbar region

Pectoralis major

large chest muscle

Origin of pectoralis major

anterior surface of ribs 3-5

Insertion of pectoralis major

coracoid process of scapula

Action of pectoralis major

protracts and rotates scapula downward

Serratus anterior

"fingers"

Origin of serratus anterior

muscle slips from ribs 1-8

Insertion of serratus anterior

anterior surface of vertebral border of scapula

Action of serratus anterior

rotates scapula upward

Trapezius

broad back muscle

Origin of trapezius

occipital bone and spines of C7, thoracic vertebrae

Insertion of trapezius

acromion and spine of scapula, lateral third of clavicle

Action of trapezius

stabilizes, elevates, retracts, and rotates scapula, extends head

Levator scapulae

Origin of levator scapulae

transverse processes of C1-C4

Insertion of levator scapulae

medial border of scapula

Action of levator scapulae

elevates and adducts scapula

Rhomboids (major and minor)

Origin of rhomboids

spinous processes of C7-T5

Insertion of rhomboids

medial border of scapula

Action of rhomboids

stabilize scapula

Deltoid

shoulder muscle

Origin of deltoid

lateral clavicle, acromion and spine

Insertion of deltoid

deltoid tuberosity of humerus

Action of deltoid

abduction of arm

Latissimus dorsi

broad back muscle

Origin of latissimus dorsi

indirectly to spines of lower 6 thoracic vertebrae, lumbar vertebrae, lower 3-4 ribs, and iliac crest

Insertion of latissimus dorsi

intertubercular groove of humerus

Action of latissimus dorsi

arm extension, also adduction and medial rotation

Teres major

Origin of teres major

posterior scapula at inferior angle

Insertion of teres major

crest of lesser tubercle of humerus

Action of teres major

extends, medially rotates, and adducts the arm

Subscapularis muscle

rotator cuff muscle

Origin of subscapularis

subscapular fossa of scapula

Insertion of subscapularis

lesser tubercle of humerus

Action of subscapularis

medially rotates arm

Supraspinatus

rotator cuff muscle

Origin of supraspinatus

supraspinous fossa of scapula

Insertion of supraspinatus

greater tubercle of humerus

Action of supraspinatus

abducts arm

Infraspinatus

rotator cuff muscle

Origin of infraspinatus

infraspinous fossa of scapula

Insertion of infraspinatus

greater tubercle of humerus

Action of infraspinatus

laterally rotates arm

Teres minor

rotator cuff muscle

Origin of teres minor

lateral border of dorsal scapula

Insertion of teres minor

greater tubercle of humerus

Action of teres minor

laterally rotates arm

Triceps brachii

posterior brachial region

Origin of triceps brachii

glenoid fossa area of scapula, posterior shaft of humerus

Insertion of triceps brachii

olecranon of ulna

Action of triceps brachii

forearm extensor

Biceps brachii

anterior brachial region

Origin of biceps brachii

coracoid process, upper ridge of glenoid cavity

Insertion of biceps brachii

radial tuberosity

Action of biceps brachii

forearm flexor

Brachialis

anterior brachial region

Origin of brachialis

anterior surface of distal humerus

Insertion of brachialis

coronoid process of ulna

Action of brachialis

forearm flexor

Brachioradials

anterior brachial region

Origin of brachioradials

lateral supracondylar ridge of humerus

Insertion of brachioradials

styloid process of radius

Action of brachioradials

forearm flexor

Pronator teres

Origin of pronator teres

medial epicondyle of humerus, coronoid process of ulna

Insertion of pronator teres

lateral radius

Action of pronator teres

pronates forearm

Palmaris longus

Origin of flexor carpi redialis

medial epicondyle of humerus

Insertion of flexor carpi redialis

base of metacarpals II and III

Action of flexor carpi redialis

flexor of hand

Flexor carpi redialis

Origin of palmaris longus

medial epicondyle of humerus

Insertion of palmaris longus

palmar aponeurosis

Action of palmaris longus

tenses skin and palmar fascia

Flexor carpi ulnaris

Origin of flexor carpi ulnaris

medial epicondyle of humerus, olecranon and posterior surface of ulna

Insertion of flexor carpi ulnaris

pisiform and hamate, base of metacarpal V