Week 11 Muscles of the Head, Neck, and Torso

agonist

the muscle responsible for facilitating a specified movement (prime mover)

antagonist

• the muscle responsible for performing the opposing action to the agonist

• maintains balance of joint by resisting the agonist

synergist

• aids the agonist to produce a movement

• support system to actions

• fixators: stabilizers

fulcrum

pivot of a lever joint

first class lever system

• EFL

• muscle effort (force) and load (resistance) act on opposite sides of the fulcrum

• neck flexion and extension: effort- posterior neck muscles, fulcrum- C1 and skull, load- head

second class lever system

• FLE

• load is between the fulcrum and effort

• mechanically advantaged b/c of longer distance btwn. fulcrum and effort - fatigue resistant

• calf raises: fulcrum- ball of foot, load- body weight, effort- gastrocnemius

third class lever system

• FEL

• effort is between the fulcrum and load

• mechanically disadvantaged bc of shorter distance btwn. fulcrum and effort

• bicep curls: fulcrum- elbow, effort- bicep, load- weight in hands

origin

• proximal attachment site, fixed to a bone

• does not move during contraction

• during contraction muscle moves towards the origin

insertion

• distal attachment site, moveable bone

• attaches across a joint that the muscle acts on

• insertion moves toward origin

occipotofrontalis/epicranius

• draws the scalp posteriorly

• raises the eyebrows and wrinkles the forehead horizontally

corrugator supercilii

• draws the eyebrows downward and medially

• makes angry eyebows and wrinkles the forehead vertically

orbicularis oculi

closes the eyelids

levator palpebrae superioris

• elevates and retracts the eyelids

• keeps the eyelids open

Label numbers 1-4 Muscles of Facal Expression in order

right occipitofrontalis, right auricularis superior, right auricularis anterior, right zygomaticus major

Label 5-9 Muscles of Facal Expression in order

right depressor supercilli, left procerus, right orbicularis oculi, right nasalis transverse portion, and orbicularis oris

what is the function of the superficial portion of the orbicularis oris?

closes and protrudes lips

what is the function of the deep portion of the orbicularis oris?

presses lips against teeth and is important for speech production

levator labii superioris

raises upper lip inferiorly and laterally

depressor labii inferioris

• draws lower lip inferiorly and laterally

• exposes lower teeth while smiling

leavator anguli oris

raises the angle of the mouth

depressor anguli oris

draws angle of the mouth laterally and downward

buccinator

compresses cheeks during the chewing process

risorius

retracts the angle of the mouth

platysma

depresses the lower jaw (mandible)

Label the seven muscles of the upper mouth

right levator labii superioris alaeque nasi, right labii superioris, right levator anguli oris, right zygomaticus minor, right zygomaticus major, right buccinator, orbicularis oris

superior rectus

adducts, elevates, and internally rotates the eye

inferior rectus

depresses and adducts the eyeball

medial rectus

adducts and moves the eye medially

lateral rectus

abducts and moves the eye laterally

superior oblique

medially rotates the eye (intorsion)

inferior oblique

laterally rotates the eye (extorsion)

deep masseter

raises the mandible against the maxilla with great force

temporalis

elevates and retracts the mandible against the maxilla with great force

medial pterygoid

elevate mandible

lateral pterygoid

depresses mandible

label the five muscles of mastication

right temporalis, right lateral pterygoid, right medial pterygoid, right deep masseter, and right superficial masseter

what are the three tongue muscles?

tongue, styloglossus, and the hyoglossus

tongue

• manipulates food

• assists in swallowing and speech production

styloglossus

• draws the sides of the tongue upward

• retracts the tongue (roll your tongue like a hot dog)

hyglossus

depresses and retracts the tongue (down and flat)

what are the three neck muscles?

sternocleidomastiod, splenius cervicis, and the scalenes

sternocleidomastoid

• draws head toward shoulder of same side

• rotates head to the opposite side

• flexes the cervical spine

• assists in elevating the thorax

scalenes

• elevates the 1st and 2nd rib

• tilts the neck to the same side

Label 1-3

right sternocleidomastoid, right splenius cervicis, left scalenes

diaphragm

• expands the thoracic cavity

• compresses the abdominal cavity

external intercostals

• elevates the ribs

• aids in normal inspiration

internal intercostals

• depresses the ribs

• aids in forced expiration

pectoralis minor

• elevates ribs

• draws scapula down and medially

serratus anterior

• protracts scapulae (upward rotation where the glenoid cavity moves superiorly)

• holds scapula close to thoracic wall

• elevates ribs

trapezius

• rotation, retraction, elevation, and depression of scalpula

• extends neck

• aids in shoulder stabilization

levator scapulae

elevates scalpula medially and upward

rhomboid major

• steadies the scapula

• retracts the scapula

• rotates scapula to depress the glenoid cavity

• moves the inferior angle of the scapula posteriorly and superiorly

label 1-6

right serratus posterior superior, right scalene, right pectoralis minor, right external intercostal, right serratus anterior, diaphragm

what are the four abdominal muscles?

rectus abdominis, external oblique, internal oblique, and transverse abdominis

rectus abdominis

• vertebral column

• tenses abdominal wall

• compresses abdominal viscera

• 6 pack muscles

external oblique

• bilaterally- compresses the abdomen and flexes the spine

• unilaterally- laterally flexes trunk to same side and rotates trunk to the opposite side

internal oblique

• bilaterally- compresses abdominal viscera and flexes the spine

• unilaterally- laterally flexes and rotates spine to same side

transverse abdominis

• compresses abdominal viscera

• tenses abdominal wall

• deepest layer or abdominal muscle

Label 1-6

left internal intercostal, right transversus thoracis, right serratus posterior inferior, left rectus abdominis, left internal oblique, left transversus abdominis

splenius

• supports the head while erect

• moves head backwards

• draws head to one side and slightly rotates it

erector spinae

longissimus, spinalis, semispinalis

longissimus - dorsi (thoracis), cervicis (colli), capitis

• dorsi - extends and laterally flexes spine, aids in rib compression

• cervicis - extends and laterally flexes spine

• capitis - extends head (bilaterally), flexes head, and turns to the same side (unilaterally)

spinalis - theoracis, cervicis (colli)

• thoracis- extends spine

• cervicis- extends head

semispinalis - capitis, cervicis (colli), thoracic

• together they extend the head

• independently they laterally flex and rotate the head

multifidus

stabilizes vertebral in localized movements of vertebral column

rotatores

extend and rotate vertebral column

quadratus lumborum

• depresses 12th rib

• unilaterally raises the pelvis

• aids in lumbar spine lateral flexion

• major stabilizer of lumbar spine

Label muscles 1-8 of the vertebral column

left semispinalis capitis, right splenius capitis, left semispinalis thoracis, right spenlius cervicis, left iliocostalis, right spinalis, left longissimus, and left quadratus lumborum