Anatomy Chapter 10A: Muscles of the Head and Neck
Terms
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- Epicranius
- Bipartite muscle consisting of the frontalis and occipitalis muscles connected by a cranial aponeurosis.
- Frontalis
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Covers forehead and dome of skull. Part of epicranius.
O: galea aponeurotica
I: skin of eyebrows and root of nose
A: raises the eyebrows & wrinkles forehead - Occipitalis
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Overlies posterior occiput
O: occipital and temporal bones
I: galea aponeurotica
A: fixes aponeurosis and pulls scalp posteriorly. - Orbicularis Occuli
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Thin, tripartite sphincter muscle of eyelid; surrounds rim of orbit.
O: frontal and maxillary bones, ligaments around orbit
I: tissue of eyelid
A: protects eyes from intense light and injury; blinking, squinting, draws eyebrows down. - Zygomaticus
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Muscle pair (major and minor) extending diagonally from cheekbone to corner of mouth.
O: zygomatic bone
I: skin and muscle at corner of mouth
A: raises lateral corners of mouth upward ("smiling muscle") - Risorius
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Slender muscle inferior and lateral to zygomaticus
O: lateral fascia associated with masseter muscle
I: skin at angle of mouth
A: Draws corner of lip laterally
Synergist of zygomaticus. - Levator Labii Superioris
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Thin muscle between obicularis oris and inferior eye margin.
O: zygomatic bone and infraorbital margin of maxilla
I: skin/muscle of upper lip
A: opens lips, raises upper lip - Depressor Labii Inferioris
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Small muscle running from mandible to lower lip
O: body of mandible lateral to its midline
I: skin and muscle of lower lip
A: draws lower lip into pout - Orbicularis Oris
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Multilayered muscle of the lips with fibres that run in many different directions, mostly circularly.
O: arises indirectly from maxilla and mandible
I: encircles mouth
A: closes/purses/protrudes lips - Mentalis
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One of the muscle pair forming a V-shaped muscle mass on the chin
O: mandible, below incisors
I: skin of chin
A: protrudes lower lip & wrinkles chin - Buccinator
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Thin, horizontal cheek muscle deep to masseter
O: molar region of maxilla and mandible
I: orbicularis oris
A: draws corner of mouth laterally, compresses cheek, holds food between teeth during chewing - Platysma
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Unpaired, thin, sheetlike superficial neck muscle
O: fascia of chest (over pecs and delts)
I: lower margin of mandible and skin/muscle at corner of mouth
A: Helps depress mandible, tenses skin of neck - Masseter
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Powerful muscle that covers lateral aspect of mandibular ramus.
O: zygomatic arch and maxilla
I: angle and ramus of mandible
A: Prime mover of jaw closure. - Temporalis
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Fan-shaped muscle that covers parts of the temporal, frontal, and parietal bones
O: temporal fossa
I: coronoid process of mandible via a tendon that passes deep to zygomatic arch
A: Closes jaw - Digastric
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Consists of two bellies united by an intermediate tendon, forming a V shape under the chin
O: lower margin of mandible and mastoid process of the temporal bone
I: connected to hyoid via CT loop
A: elevate hyoid bone and steady it during swallowing and speech - Mylohyoid
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Flat, triangular muscle just deep to digastric muscle. Floor of anterior mouth.
O: medial surface of mandible
I: hyoid bone and median raphe
A: Elevates hyoid bone and floor of mouth, enables backward/upward pressure of tongue for swallowing. - Sternohyoid
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Most medial muscle of the neck. Superficial except where covered by sternocleidomastoid.
O: manubrium & medial end of clavicle
I: lower margin of hyoid bone
A: depresses larynx and hyoid bone if mandible is fixed - Sternocleidomastoid
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Two-headed muscle located deep to platysma on anterolateral surface of neck.
O: manubrium of sternum and medial portion of clavicle
I: mastoid process of temporal bone and superior nuchal line of occipital bone.
A: prime mover of active head flexion - Scalenes
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Located more laterally than anteriorly on neck. Deep to platysma and sternocleidomastoid.
O: transverse processes of cervical vertebrae
I: anterolaterally on first two ribs
A: elevate first tow ribs, flex and rotate neck - Splenius
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Broad bipartite superficial muscle extending from upper thoracic vertebrae to skull. Holds down deeper neck muscles.
O: Ligamentum nucae (ligament extending from occipital bone along the tips of the spinous processes of the cervical vertebrae), spinous processes of C7-T6
I: mastoid process of temporal bone & occipital bone, transverse processes of C2-C4 vertebrae
A: extend or hyperextend head