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The origin is
the end of the muscle that is attached to the least movable structure
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The insertion is
the other end of the muscle and is attached to the more movable structure
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What does The sternocleidomastoid muscle do
balances positions and turns the head
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To feel the sternocleidomastoid muscle you would ask the patient to
turn to the left
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The muscles of the head and neck are divided according to function into what six main groups
- cervical muscles
- muscles of facial expression
- muscles of mastication
- hyoid muscles
- muscles of the tongue
- muscles of the pharynx
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Name the two cervical muscles
sternocleidomastoid and trapezius
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One of the largest and most superficial cervical muscles is the paired
sternocleidomastoid muscle (SCM)
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The SCM originates from the ______ to insert at the
- clavicle and the sternum and passes posteriorly and superiorly
- on the mastoid process of the temporal bone
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The SCM is innervated
by the eleventh cranial or accessory nerve
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Which muscle is superficial to both the lateral and posterior surfaces of the neck
trapezius muscle
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The trapezius muscle originates from ______ and inserts at _______
- the occipital bone and the posterior midline of the cervical and thoracic regions
- on the clavicle and the scapula
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All the muscles of facial expression originate from ______ and inserts on _______
- from the surface of the skull bone
- dermis of skin tissue
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All the muscles of facial expression are innervated by
the seventh cranial or facial nerve
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The _________ is a muscle of facial expression in the scalp region
epicranial muscle or epicranius
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Epicranial muscle has two bellies called
frontal and occipital
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The bellies of the epicranial are separated by
a large, spread-out scalpal tendon, the epicranial aponeurosis
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The frontal belly inserts into the skin
of the eyebrow and root of the nose
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What do both bellies of the epicranial muscle do
raise the eyebrows and scalp, as when a person shows surprise
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The ______ muscle is a muscle of facial expression that encircles the eye
orbicularis oculi
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What action does the orbicularis oculi muscle do
This muscle closes the eyelid
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Where is the corrugator supercilii muscle located
deep to the superior part of the orbicularis oculi muscle
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What actions does the corrugator supercilii muscle do
This muscle draws the skin of the eyebrow medially and inferiorly toward the nose, which causes vertical wrinkles in the glabella area of the forehead and horizontal wrinkles at the bridge of the nose, as when a person frowns
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What are the three muscles associated with the nasal region
nasalis, the procerus, and the depressor septi nasi
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The largest and best developed of the nasal muscles is the
nasalis
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What action does the nasalis do
flare the nares
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What mucle acts to shape and control the size of the mouth opening
orbicularis oris muscle
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What action does the orbicularis oris muscle perform
pressing together (closing lips), tightening and thinning (pursing lips), rolling inward between the teeth (grimacing), and thrusting outward (pouting and kissing
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The buccinator muscle is a thin quadrilateral muscle of facial expression that forms
the anterior part of the cheek or the lateral wall of the oral cavity
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What are the actions of the buccinator muscle
- assists the muscles of mastication
- keep food pushed back on the occlusal surface of the posterior teeth, as when a person chews
- pulls each labial commisssure laterally and shortens the cheek both vertically and horizontally
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What action does the risorius muscle perform
- stretch the lips laterally, retracting the labial commissure and widening the oral cavity.
- produces more of a grimace
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What action does the levator labii superioris muscle perform
It elevates the upper lip
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What action does the levator labii superioris alaeque nasi muscle perform
elevates the upper lip and ala of the nose, thus also dilating each naris, as in a sneering expression
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What action does the zygomaticus major muscle perform
elevates the labial commissure of the upper lip and pulls it laterally, as when a person smiles
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What action does the zygomaticus minor muscle perform
It elevates the upper lip, assisting in smiling
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What action does the levator anguli oris muscle perform
It elevates the labial commissure, as when a person smiles
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What action does the depressor anguli oris muscle perform
It depresses the angle of the mouth, as when a person frowns
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What action does the depressor labii inferioris perform
- It depresses the lower lip, exposing the mandibular incisor teeth
- Some experts have suggested that it expresses irony
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What action does the mentalis muscle perform
It raises the chin, wrinkling the skin, causing the displaced lower lip to protrude, and narrowing the oral vestibule
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What action does the platysma muscle perform
- This muscle raises the skin of the neck to form noticeable vertical and horizontal ridges and depressions
- It can also pull the labial commissures down, as when a person grimaces
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The action of the muscle is
The movement that is accomplished when the muscle fibers contract
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What does contralateral mean
structure on opposite side
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What is the action of the trapezius muscle
The trapezius muscle acts to lift the clavicle and scapula, as when the shoulders are shrugged
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