Action of muscles (1)
Terms
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- Frontalis
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Raises skin on forehead
Raises eyebrows - Occipitalis
- Draws scalp back
- Orbicularis Oris
- Closes and shapes lips
- Obicularis Oculi
- Closes eyes
- Platysma
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Draws outer part of lip down (inferior) and posteriorly as is pouting
depresses mandible - Buccinator
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Trumpeter muscle
Presses cheeks in whistling, blowing, and sucking assists in mastication
draws corners of lips laterally - Corrugator
- Draws eyebrows inferiorly wrinkles skin of forehead vertically as in frowning
- Masseter
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a chewer
elevates mandible (closing)
retracts mandible (draws back) - Temporalis
- Elevates and retracts mandible
- Sternocleidomastoideus
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Acting together (bilaterally), flex cervical portion of vertebral column, extend head, and elevates the sternum during forced exhalation
acting singly (unilaterally), laterally flex and rotate head to side opposite contracting muscle - Rectus Abdominis
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Flexes vertebral column (lumbar)
compresses abdomen to aid during defacation, urination, forced exhalation, and child birth. - External Oblique
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Bilaterally, compresses abdomen and flex vertebral column
unilaterally, laterally flex and rotates vertebral column - Internal Oblique
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compress abdomen
flex vertebral column
laterally flex vertebral column
unilaterally, rotate vertebral column - Transverse Abdominis
- compress abdomen
- Diaphram
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powers breathing
Contraction of the this muscle causes it to flatten and increases the vertical dimension of the thoracic cavity, resulting in inhalation
relaxation of this muscle causes it to move superiorly and decreases the vertical dimension of the thoracic cavity, resulting in exhalation - Ext. Intercostals
- elevate ribs during exhalation
- Int. Intercostals
- contraction draws adjacent ribs together to further decrease dimensions of thoracic cavity during forced exhalation
- Pectoralis Minor
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Abducts scapula and rotates downward
elevates 3rd to 5th ribs during forced inhalation when scapula is fixed - Serratus Anterior
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Abduct scapula and rotates upward
elevates ribs when scapula is stabilized
"boxer's muscle"
important in horizontal arm movements (punching) - Trapezius
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elevate scapula and help extend head
middle fibers adduct scapula
inferior fibers depresses scapula
sup. and inf. fibers together rotate scapula upward
stabilizes scapula - Levator scapulae
- Elevates scapula and rotates it downward
- Rhomboids (major and minor)
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Elevates and adducts scapula and rotates it downward
stabilizes scapula - Pectoralis Major
- adducts and medially rotates arm at shoulder joint
- Latissimus Dorsi
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Extends, adducts, and medially rotates arm at shoulder joint
draws arm inferiorly and posteriorly - Coracobrachialis
- Flexes and adducts arm at shoulder joints
- Deltoid
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abducts arm, flex shoulder and medially rotates arm (ant. fibers)
extend shoulder and laterally rotates arm (post. fibers) - Supraspinatus
- Assists deltoid muscle in abducting arm at shoulder joint
- Infraspinatus
- Laterally rotates and adducts arm at shoulder joint
- Teres Major
- adducts and extends the arm and rotates it medially.
- Teres minor
- Laterally rotates, extends, and adducts arm at shoulder joint.
- Biceps Brachii
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flexes the forearm at elbow joint
supinates the forearm at the radioulnar joints
Flexes the arm at the shoulder joint - Brachialis
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Flexes forearm at elbow joint
most powerful flexor of the forearm at elbow joint
"workhouse" - Triceps brachii
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Extends forearm at elbow joint
Extends arm at elbow joint - Anconeus
- assists the triceps brachii in extending the forearm at the elbow joint
- Supinator
- supinates the forearm at radioulnar joints
- Pronator teres
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Pronates forearm at radioulnar joints
Weakly flexes forearm at elbow joint