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Action of muscles (1)


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Raises skin on forehead
Raises eyebrows
Draws scalp back
Orbicularis Oris
Closes and shapes lips
Obicularis Oculi
Closes eyes
Draws outer part of lip down (inferior) and posteriorly as is pouting
depresses mandible
Trumpeter muscle
Presses cheeks in whistling, blowing, and sucking assists in mastication
draws corners of lips laterally
Draws eyebrows inferiorly wrinkles skin of forehead vertically as in frowning
a chewer
elevates mandible (closing)
retracts mandible (draws back)
Elevates and retracts mandible
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
Flexes vertebral column (lumbar)
compresses abdomen to aid during defacation, urination, forced exhalation, and child birth.
External Oblique
Bilaterally, compresses abdomen and flex vertebral column
unilaterally, laterally flex and rotates vertebral column
Internal Oblique
compress abdomen
flex vertebral column
laterally flex vertebral column
unilaterally, rotate vertebral column
Transverse Abdominis
compress abdomen
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
Abducts scapula and rotates downward
elevates 3rd to 5th ribs during forced inhalation when scapula is fixed
Serratus Anterior
Abduct scapula and rotates upward
elevates ribs when scapula is stabilized
"boxer's muscle"
important in horizontal arm movements (punching)
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)
Elevates and adducts scapula and rotates it downward
stabilizes scapula
Pectoralis Major
adducts and medially rotates arm at shoulder joint
Latissimus Dorsi
Extends, adducts, and medially rotates arm at shoulder joint
draws arm inferiorly and posteriorly
Flexes and adducts arm at shoulder joints
abducts arm, flex shoulder and medially rotates arm (ant. fibers)
extend shoulder and laterally rotates arm (post. fibers)
Assists deltoid muscle in abducting arm at shoulder joint
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
flexes the forearm at elbow joint
supinates the forearm at the radioulnar joints
Flexes the arm at the shoulder joint
Flexes forearm at elbow joint
most powerful flexor of the forearm at elbow joint
Triceps brachii
Extends forearm at elbow joint
Extends arm at elbow joint
assists the triceps brachii in extending the forearm at the elbow joint
supinates the forearm at radioulnar joints
Pronator teres
Pronates forearm at radioulnar joints
Weakly flexes forearm at elbow joint

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