Muscular System

frontalis

draws scalp anteriorly; raises eyebrows; wrinkles forehead

temporalis

for mastication; elevates mandible and closes the jaw

orbicularis oris

closes the mouth and puckers the lips

orbicularis oculi

closes the eye

sternocleidomastoid

both muscles: flex head; one muscle: rotates head toward the opposite shoulder

trapezius

extends the head and rotates the scapula

medial pterygoid

raises the jaw

platysma

depresses the mandible

trapezius

extends head and scapula

levator scapula

raises scapula

rhomboideus

retracts the scapula

Latissimus dorsi

extends the shoulders and adducts arm

teres major

extends the shoulders

infraspinatus

extends and rotates arm

external intercostals

expand the thorax

pectoralis minor

depresses the scapula

serratus anterior

protracts the scapula

internal abdominal obliques

compresses the abdomen (deep)

rectus abdominis

flexes vertebral and column increases the pressure of the abdomen

deltoid

abducts the arm; flexes and extends shoulders

biceps brachii

flexes the elbow and supinates the arm

brachioradialis

flexes forearm (synergist of brachialis)

extensor carpi radialis longus

extends and abducts the wrist

extensor digitorum

extends fingers and flares or adducts fingers

flexor carpi ulnaris

flexes and adducts the hand at wrist joint

pronator teres

pronates the forearm

biceps femoris

extends the thigh and laterally flexes the knee

semitendinosus

extends the thigh, flexes the knee, and rotates the leg medially

gastrocnemius

plantar flexes the foot (bigger)

soleus

plantar flexes the foot (smaller)

extensor digitorum longus

dorsiflexes the foot

levator ani

constricts the anus, urethra, and vagina; resists increased intra-abdominal pressure; and supports fetal head during childbirth

ischiocavernosus

erection

•Biceps femoris
•Semitendinosus
•Semimembranosus

hamstring muscles

1.movement
2.maintain posture
3.respiration
4.production of body heat
5.communication
6.heart beat
7.contraction of organs and vessels

functions of the muscular system

intrinsic muscle

refers to a muscle having its origin and insertion located in the same body region

extrinsic muscle

refers to a muscle having its origin in a different body region and the insertion

fixator

a muscle that holds an origin stable for another muscle

synergists

muscles that have the same action

extension

action that bends a part of the body posteriorly

abduction

movement of a part of the body away from the midline

retraction

movement that brings part of the body backward

plantar flexion

position of standing on tiptoes with the heels off the floor

inversion

position in which the soles of the feet are together, facing each other

eversion

position in which the soles of the feet point away from each other

rotation

the act of spinning on an axis

circumduction

the act of making a circle with part of the body

pronation

rotation that turns the palms down

elevation

the act of closing the jaw or raising the shoulders

occipitalis

draws scalp posteriorly

buccinator

for mastication; compresses cheeks (as in blowing or whistling)

masseter

for mastication; raises jaw

levator labii superioris

elevates the upper lip

zygomaticus major

raises the angle of the mouth (as in smiling)

zygomaticus minor

elevates the upper lip and exposes maxillary teeth

depressor anguli oris

depresses the angle of the mouth

lateral pterygoid

lowers the jaw

gluteus medius

abducts the thigh and medially rotates it

gluteus maximus

facilitates extension at hip joint

supraspinatus

abducts the arm

internal intercostals

compress the thorax

pectoralis major

controls the movement of the arm; adducts and medially rotates arm

external abdominal obliques

compresses the abdomen (superficial)

transverse abdominal

compresses the abdomen

brachialis

flexes arm

extensor carpi ulnaris

extends and adducts the wrist

palmaris longus

weakly flexes the hand at wrist joint

flexor carpi radialis

flexes the wrist and abducts the hand

semimembranosus

extends the thigh, flexes the knee, and rotates the leg medially (deep)

peroneus/fibularis

plantar flexes the foot and everts the foot

tibialis anterior

dorsiflexes the foot (prime mover) and inverts the foot

plantaris

plantar flexes the foot and flexes leg at the knee joint

bulbospongiosus

Male: aids in urine and semen expulsion, and erection of penis; Females: constricts vaginal orifice, and assists in the erection of the clitoris

superficial transverse perineus

stabilizes central tendon of perineum

coccygeus

supports pelvic viscera; resists intra-abdominal pressure; and pulls coccyx anteriorly after defecation or childbirth

erector spinae
•iliocostalis
•longissimus
•spinalis

maintains erect posture of the vertebral column

scalenes
•scalenus anterior
•scalenus medius
•scalenus posterior

raise the ribs and expand the thorax

•scalenus anterior
•scalenus medius
•scalenus posterior

scalenes

•iliocostalis
•longissimus
•spinalis

erector spinae muscles

prime mover

the main muscle of the synergists that performs the action

antagonist

a muscle that has an opposing action

flexion

action that bends a part of the body anteriorly, such as flexing the elbow

adduction

movement of a part of the body toward the midline

protraction

movement that brings part of the body forward

lateral excursion

movement of the jaw laterally to either side

medial excursion

movement of the jaw back to the midline

dorsiflexion

position of standing on the heels with the toes pointing up off the floor

supination

rotation that turns the palms up

opposition

the act of bringing the thumb to the palm

reposition

the act of taking the thumb away from the palm

depression

the act of opening the jaw or lowering the shoulders