Term
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Definition
Temporalis
Action: Elevation of mandible during mastication (chewing) |
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Term
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Definition
Masseter
Action: Elevation of the mandible, with smaller roles in protraction, retraction, and lateral and medial excursion (mastication) |
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Definition
Orbicularis Oculi
Action: sphincter of the eyelids; closes eye in blinking, squinting, and sleep; aids in flow of tears across eye |
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Term
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Definition
Levator Palpabrae Superioris
Action: Elevates upper eyelid; opens eye |
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Term
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Definition
Orbicularis Oris
Action: encircles mouth, closes lips, protrudes lips as in kissing; uniquely developed in humans for speech |
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Term
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Definition
Platysma
Action: Draws lower lip and angle of mouth downward in expressions of horror or surprise; may aid in opening mouth widely |
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Term
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Definition
Sternocleidomastoid
Origin: Manubrium of sternum; medial one-third of clavicle
Insertion: Mastoid process of temporal bone
Action: Unilateral action tilts head slightly upward and toward the opposite, as in looking over one’s contralateral shoulder. Rotating head left or right. Bilateral action draws head straightforward and down. |
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Term
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Definition
Scalenes
Action: Bilateral contraction flexes neck. If spine is fixed, scalenes elevate ribs 1-2 and aid in breathing |
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Term
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Definition
Digastric
Action: Depresses mandible when hyoid is fixed; opens mouth widely, as when ingesting food or yawning; elevates hyoid when mandible is fixed |
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Term
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Definition
Stylohyoid
Origin: Styloid process of temporal bone
Insertion: Hyoid bone
Action: Elevates and retracts hyoid |
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Term
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Definition
Mylohyoid
Origin: inferior margin of mandible
Insertion: Hyoid bone
Action: Spans mandible from side to side and forms floor of mouth; elevates floor of mouth in initial stage of swallowing |
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Term
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Definition
Sternohyoid
Origin: Manubrium of sternum; medial end of clavicle
Insertion: Hyoid bone
Action: Depresses hyoid after it has been elevated |
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Term
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Definition
Sternothyroid
Action: Depresses larynx after it has been elevated in swallowing and vocalization |
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Definition
Omohyoid
Action: Depresses hyoid after it has been elevated |
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Term
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Definition
Thyrohyoid
Action: Depresses hyoid |
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Term
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Definition
External Intercostals
Action: When scalenes fix rib 1, external intercostals elevate and protract ribs 2-12, expanding the thoracic cavity and creating a partial vacuum causing inflow of air |
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Term
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Definition
Internal Intercostals
Action: In inspiration, the intercartilaginous part aids in elevating the ribs and expanding the thoracic cavity; in expiration, the interosseous part depresses and retracts the ribs, compressing the thoracic cavity and expelling air |
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Term
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Definition
Diaphragm
Action: prime mover of inspiration; contraction compresses abdominal viscera and aids in childbirth and expulsion of urine and feces |
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Term
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Definition
Rectus Abdominis
Action: Flexes trunk, stabilizes pelvic region during walking; and compresses abdominal viscera |
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Definition
External Abdominal Oblique
Action: Support viscera; stabilizes vertebral column; maintains posture |
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Definition
Internal Abdominal Oblique
Action: Support viscera; stabilizes vertebral column; maintains posture; unilateral contraction causes ipsilateral rotation of waist |
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Term
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Definition
Transverse Abdominis
Action: Compresses abdominal contents; does not contribute to vertebral column movements |
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Term
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Definition
Linea Alba
Non-muscular, fibrous structure running between the xiphoid process and pubic symphysis
Insertion site for transverse abdominis |
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Term
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Definition
Iliocostalis
Part of Erector Spinae Group
Action: lateral flexion of vertebral column; extension of vertebral column; depression of ribs
“Antigravity” muscle |
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Term
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Definition
Longissimus
Part of Erector Spinae group
Action:
Unilateral: lateral flexion of vertebral column and rotation of head
Bilateral: extension of vertebral column and head
Depresses ribs
“Antigravity” muscle |
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Term
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Definition
Spinalis
Action:
Unilateral: lateral flexion of vertebral column
Bilateral: extension of vertebral column
“Antigravity” muscle |
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