Muscles (Mainly actions of them) of Anatomy 10/25

Synergists

group of muscles working together to cause movement EX: two extensors

Antagonists

Group or individual muscles working in opposition to each other EX: a flexor and an extensor

Prime Mover

One muscle in a group of synergists that accomplishes the major desired movement EX: many muscles flex the hip but the iliopsoas is the prime flexor

Flexion

Bringing two ventral surfaces closer together, decreases the angle between two bones (EX: bending your elbow to bring your hand toward your shoulder.)

Extension

Moving two primary ventral surfaces further apart, increases angle between two parts (EX: straightening the lower leg from a bent position like standing up from a chair.)

Dorsiflexion

Bringing the toes toward the shin

Plantar Flexion

Flexion of foot (EX: curling the toes)

Pronation

Make the palm face the posterior in the Anatomical Position

Supination

Make the palm face the anterior in the Anatomical Position

Inversion

Turning sole of foot medially at ankle

Eversion

Turning sole of foot laterally at ankle

Head & Neck Movement includes

Flexion-Extension, Rotation, Lateral Flexion

Trunk (torso) Movement includes

Flexion-Extension, Rotation, Lateral Flexion

Jaw Movement includes

Protraction-Retraction, Elevation-Depression

Shoulder Movement includes

Elevation-Depression, Protraction-Retraction, Rotation

Epicranius (occipitofrontalis) includes

Frontalis and Occipitalis

Frontalis origin is

Epicranial Aponeurosis

Aponeurosis is

a broad flat expanse of tendon, dense CT that anchors muscles to bone

Frontalis insertion is

Skin of eyebrows and root of nose

Frontalis action is

Raises the eyebrows, wrinkles skin forehead horizontally

Occipitalis origin is

Occipital and Temporal bones

Occipitalis insertion is

Epicranial Aponeurosis

Occipitalis action is

Fixes aponeurosis, tightens scalp, pulls scalp posteriorly

Obicularis Oris is

the multilayered muscle of the lips with fibers running in different directions but mainly circularly.

Orbicularis Oris origin is

arises indirectly from maxilla and mandible; fibers blend with fibers of other facial muscles associated with the lips.

Orbicularis Oris insertion is

Encircles mouth, inserts into muscle and skin at angles of mouth

Orbicularis Oris action is

Closes lips, protrudes and purses lips, kissing and whistling muscle

Orbicularis Oculi is

the thin, flat muscle of the eyelid; surrounds rim of the orbit

Orbicularis Oculi origin is

frontal and maxillary bones and ligaments around orbit

Orbicularis Oculi insertion is

tissue of eyelid

Orbicularis Oculi action is

closes eyes, blinking, winking squinting, draws eyebrows inferiorly

Zygomaticus includes

Zygomaticus Major and Zygomaticus Minor

Zygomaticus is

a muscle pair extending diagonally from cheekbone to corner of mouth

Zygomaticus origin is

Zygomatic bone

Zygomaticus insertion is

skin and muscle at corner of mouth

Zygomaticus action is

raises lateral corners of mouth upward, smiling muscle

Buccinator is

thin, horizonal cheek muscle; principal muscle of cheek; deep to masseter

Buccinator origin is

molar region of maxilla and mandible, runs from rami of mandible to corner of mouth

Buccinator insertion is

Orbicularis Oris

Buccinator action is

compresses cheek, (as in whistling and sucking) during chewing, holds food in between teeth when chewing, draws corner of mouth laterally

Platysma is

thin, very superficial neck muscle, but plays a role in facial expression

Platysma origin is

Fascia of chest, (over pectoral muscles and deltoid)

Platysma insertion is

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

Platysma action is

tenses skin of neck, pulls lower lip down as if making “eh” face

Corrugator Supercili is

small muscle, activity associated with orbicularis oculi

Corrugator Supercili origin is

arch of frontal bone above nasal bone

Corrugator Supercili insertion is

skin of eyebrow

Corrugator Supercili action is

draws eyebrows inferiorly and medially AKA “furrows brows”

Temporalis is

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

Temporalis origin is

temporal lines on skull

Temporalis insertion is

Coronoid process of mandible

Temporalis action is

elevated and retracts mandible, incisor biting, closes jaw

Masseter is

powerful muscle that covers lateral aspect of mandibular ramus

Masseter origin is

Zygomatic Arch

Masseter insertion is

angle and ramus of mandible

Masseter action is

elevates mandible, molar chewing, primary mover of jaw closure

Sternocleidomastoid (SCM) is

two-headed muscle located deep in the platysma; key muscle landmark in the neck

Sternocleidomastoid origin is

manubrium of sternum and medial portion of clavicle

Sternocleidomastoid insertion is

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

Sternocleidomastoid action is

both sides: flexion of head

one side: laterally rotates the head to opposite side

Scalenes are

muscles located laterally on neck; deep to platysma and sternocleidomastoid

Scalenes origin is

transverse process of cervical vertebrae (C1 & C2)

Scalenes insertion is

anterolaterally on first two ribs

Scalenes action is

both sides: flex neck

ones side: later flexion of neck

Pectoalis Major is

large, fan-shaped muscle covering superior portion of the chest; divided into sternum and clavicle parts

Pectoralis Major origin is

Clavicle, sternum

Pectoralis Major insertion is

Lateral edge of bicipital groove on humerous

Pectoralis Major action is

adduction and medial rotation of arm

Pectoralis Minor is

flat, thin muscle directly beneath and obscured by pectoralis major

Pectoralis Minor origin is

anterior surfaces of ribs 3-5

Pectoralis Minor insertion is

coracoid process of scapula

Pectoralis Minor action is

draws scapular forward (protraction) and downward (depression); helps elevation of ribs during inhalation

Serratus Anterior is

protracts and fixes scapula

Serratus Anterior origin is

from the lateral side of ribs 1-8

Serratus Anterior insertion is

under scapula to vertebral border of scapula

Serratus Anterior action is

Stablizes scapula for arm and shoulder muscles; called “the boxers muscle”

Diaphragm is

forms the floor of the thoracic cavity; dome shaped in its relaxed state

Diaphragm origin is

inferior, internal surface of ribcage and sternum

Diaphragm insertion is

central tendon aponeurosis

Diaphragm action is

prime mover of inspiration; flattens during contraction

Intercostals include

External and Internal intercostals

External Intercostals are

11 pairs between ribs; fibers run obliquely (down and forward) from each rib to the rib below; INSPIRATION

External Intercostal origin is

inferior border of rib above

External Intercostal insertion

superior border of rib below

External intercostal action

pulls the ribs toward one another to elevate ribcage; aids in inspiration

Internal intercostals are

11 pairs between ribs; fibers run deep to those of external intercostals (downward and posteriorly); EXPIRATION

Internal intercostal origin is

superior border of rib below

Internal intercostal insertion is

inferior border of rib above

Internal intercostal action is

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

External obliques are

hands in pockets, more superficial to internal obliques

External oblique origin is

lateral border of lower ribs

External oblique insertion is

into rectus sheath

External oblique action is

aids in lateral flexion and rotation (one side) aids in truck flexion (both sides)

Internal obliques are

perpendicular to external; diagonal fibers

Internal oblique origin is

crest of ilium

Internal oblique insertion is

in posterior side of rectus sheath

Internal oblique action is

aid in trunk flexion and do rotation on the same side

Rectus Abdominis is

muscle, the 6-pack, covered by the fibrous tendon called the rectus sheath

Rectus Abdominis origin is

pubic crest and symphysis

Rectus Abdominis insertion is

inferior portion of rib cage