Muscles of the body

Frontalis

superficial to frontal bone

Origin of frontalis

epicranial aponeurosis

Insertion of frontalis

skin of eyebrows and root of nose

Action of frontalis

raises the eyebrows/wrinkles the brow

Zygomaticus

extends from cheekbones to corners of the mouth

Origin of zygomaticus

zygomatic bone

Insertion of zygomaticus

skin and muscle at corner of mouth

Action of zygomaticus

raises lateral corners of the mouth when smiling

Masseter

Origin of masseter

zygomatic arch/zygomatic bone

Insertion of masseter

angle and ramus of mandible

Action of masseter

elevates the mandible

Temporalis

Origin of temporalis

temporal fossa

Insertion of temporalis

coronoid process of mandible

Action of temporalis

elevates mandible

Sternocleidomastoid

Origin of sternocleidomastoid

manubrium of sternum and medial clavicle

Insertion of sternocleidomastoid

mastoid process of temporal bone and superior nuchal line of occipital bone

Action of sternocleidomastoid

flexes and/or laterally rotates the head

Origin of scalenes

transverse processes of cervical vertebrae

Insertion of scalenes

first two ribs

Action of scalenes

elevates first two ribs, flexes and rotates neck

Origin of splenius

ligamentum nuchae, spinous processes of C7-T6

Insertion of splenius

mastoid process of temporal bone, occipital bone

Action of splenius

extends the head

3 muscles erector spinae consists of...

-Iliocostalis

-Longissimus

-Spinalis

Origin of iliocostalis

iliac crests, lower 6 ribs

Insertion of iliocostalis

angles of ribs, transverse processes of cervical vertebrae

Action of iliocostalis

extends and laterally flexes vertebral column

Origin of longissimus

tranverse processes of cervical, thoracic, and lumbar vertebrae

Insertion of longissimus

transverse processes and ribs

Action of longissimus

extends and laterally flexes vertebral column, extends and rotates the head

Origin of spinalis

spines of upper lumbar and lower thoracic vertebrae

Insertion of spinalis

spines of upper thoracic and cervical vertebrae

Action of spinalis

extends vertebral column

External intercostals

Origin of external intercostals

inferior border of rib above

Insertion of external intercostals

superior border of rib below

Action of external intercostals

elevate the rib cage for inspiration

Internal intercostals

Origin of internal intercostals

superior border of rib below

Insertion of internal intercostals

inferior border of rib above

Action of internal intercostals

depress rib cage for forced exhalation

Diaphragm

Origin of diaphragm

inferior rib cage and sternum

Insertion of diaphragm

central tendon

Action of diaphragm

inspiration - contracts to increase intra-abdominal pressure to force air into lungs

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