Lab 7 - Muscles

origin

the attachment of the muscle that stays still

insertion

the attachment that moves during muscle action

tendons

attach muscle to bones and to other muscles

• dense fibrous connective tissue

aponeurosis

a broad flat expanse of tendon

synergists

a group of muscles working together to cause movement

• ex.) 2 flexors

antagonists

groups or individual muscles working in opposition to one another

• ex.) bicep and tricep

prime mover

one muscle in a group of synergists that accomplishes the major desired movement

• ex.) many muscle help flex the hip but the iliopsoas is the prime flexor

flexion

bringing two ventral surfaces closer together

extension

moving two primary ventral surfaces farther apart

dorsiflexion

bringing the toes toward the shin

plantar flexion

curling of the toes

• flexion of the foot

abduction

movement of a limb away from the midline

• ex.) fingers and legs

adduction

movement of a limb toward the midline

circumduction

the distal end of a bone describes a circle while the proximal end stays stationary

pronation

make the palm face posterior in AP

supination

make the palm face anterior in AP

inversion

turning the sole of the foot medially at the ankle

eversion

turning the sole of the foot laterally at the ankle

protraction

moving the mandible or clavicle anteriorly in a plane that is parallel with the grown

retraction

moving the mandible or clavicle posteriorly in place that is parallel with the ground

elevation

movement in a superior direction

depression

movement in an inferior direction

frontalis

covers forehead and dome of skull

frontalis origin

epicranial aponeurosis

frontalis insertion

skin of the eyebrows and root of nose

frontalis action

• raises the eyebrows

• wrinkles forehead skin horizontally

occipitalis

overlies posterior occiput by pulling on the epicranial aponeurosis, fixes origin of frontal belly

occipitalis origin

occipital and temporal bones

occipitalis insertion

epicranial aponeurosis

occipitalis action

• fixes aponeurosis

• tightens scalp

• pulls scalp posteriorly

epicranius

made of the frontalis muscle, epicranial aponeurosis, and the occipitalis muscle

orbicularis oris

multilayered muscle of the lips with fibers that run in different directions but most run circularly

orbicularis oris origin

indirectly from maxilla and mandible, fibers blend with the fibers of other facial muscles associated with the lips

orbicularis oris insertion

encircles mouth

orbicularis oris action

• closes lips

• purses and protrudes lips

• kissing and whistling muscle

orbicularis oculi

sphincter muscle surrounding rim of the orbit

orbicularis oculi origin

frontal and maxillary bones

orbicularis oculi insertion

tissue of eyelid

orbicularis oculi action

• closes eye

• produce blinking, squinting, and winking

• draws eyebrows inferiorly

zygomaticus

muscle pair extending diagonally from cheekbone to corner of mouth

zygomaticus origin

zygomatic bone

zygomaticus insertion

skin and muscle at corner of mouth

zygomaticus action

raises corners of mouth upward

• smiling muscle

buccinator

thin, horizontal cheek muscle; principle muscle of cheek that is deep to masseter

buccinator origin

molar region of the maxilla and mandible

• runs from rami of mandible to corner of the mouth

buccinator insertion

orbicularis oris

buccinator action

• compresses cheek for whistling, chewing, and sucking

• holds food between teeth during chewing

• draws corner of mouth laterally

platysma

thin, sheet-like superficial neck muscle, but plays a role in facial expression

platysma origin

fascia of chest (over pectoral muscles and deltoid)

platysma insertion

lower margin of mandible, and skin and muscle at corner of mouth

platysma action

• tenses skin of neck

• helps depress mandible

• pulls lower lip back and down to draw mouth downward

corrugator supercili

small muscle; works with orbicularis oculi

corrugator supercili origin

arch of frontal bone above nasal bone

corrugator supercili insertion

skin of eyebrow

curragator supercili action

draws eyebrows medially and inferiorly

• furrows brows

levator palpebrae

elevates the eyelid

muscles of mastication

temporalis and masseter

temporalis

fan-shaped muscle that covers part of the temporal, frontal, and parietal bones

temporalis origin

temporal lines on skull

temporalis insertion

coronoid process of mandible

• via a tendon that passes deep to zygomatic arch

temporalis action

• elevates and retracts mandible

• incisor biting

• closes jaw

masseter

powerful muscle that covers lateral aspect of mandibular ramus

masseter origin

zygomatic arch

masseter insertion

angle and ramus of mandible

masseter action

• elevates mandible

• molar chewing

• primary mover of jaw closure

sternocleidomastoid

two headed muscle located deep to the platysma

• key muscular landmark in the neck

• spasms of this may cause wryneck

sternocleidomastoid origin

manubrium of sternum and medial portion of the clavicle

sternocleidomastoid insertion

mastoid process of temporal bone

sternocleidomastoid action

• both sides: flexion of head

• one side: laterally rotates the head to the opposite side

scalenes

located laterally on neck; deep to platysma and sternocleidomastoid

scalenes origin

transverse process of the cervical vertebrae

scalenes insertion

anterolaterally on first two ribs

scalenes action

• flex neck (both sides)

• lateral flexion of neck (one side)

pectoralis major

large, fan shaped muscle covering superior portion of chest; divided into clavicular and sternal parts

pectoralis major origin

clavicle and sternum

pectoralis major insertion

lateral edge of bicipital groove of humerus

pectoralis major action

adduction and medial rotation of arm

pectoralis minor

flat, thin muscle directly beneath and obscured by pectoralis major

pectoralis minor origin

anterior surfaces of ribs 3-5

pectoralis major insertion

coracoid process of scapula

pectoralis minor action

• with ribs fixed, draws scapular forward and downward

• helps elevate ribs during inhalation

serratus anterior

protracts and fixes the scapula

serratus anterior origin

from the lateral sides of ribs 1-8

serratus anterior insertion

under scapula to vertebral border of scapula

serratus anterior action

stabilizes scapula for arm and shoulder muscles

• boxer’s muscle

• if not stabilized, scapula will wing out

diaphragm

forms floor of thoracic cavity; dome shaped in relaxed state

diaphragm origin

inferior, internal surface of rib cahe and sternum

diaphragm insertion

central tendon, aponeurosis

diaphragm action

prime mover of inspiration; flattens during contraction

external intercostals

11 pairs between ribs; fibers run obliquely from each rib to rib below

• inspiration

external intercostals origin

inferior border of rib above

external intercostals insertion

superior border of rib below

external intercostals action

pulls ribs toward one another to elevate rib cage; aids in inspiration

internal intercostals

11 pairs between ribs; fibers run deep to those of external intercostals

• fibers run downward and posteriorly

• expiration

internal intercostals origin

superior border of the rib below

internal intercostals insertion

inferior border (costal groove) of rib above

internal intercostals action

draw ribs together and depress rib cage; aid forced expiration; antagonistic to external intercostals

external obliques

external = hands in pockets

• more superficial

external obliques origin

lateral border of the lower ribs

external oblique insertion

rectus sheath