Download MUSCULAR SYSTEM Muscles of the head and neck

Chapter 7
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Location
Size
Direction of fibers
Number of origins
Location of origins and insertion
Action flexor
Extensor
Levator and depressor
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Muscles of the head and neck control human facial
expressions
Muscles of mastication control the mandible (lower jaw)
 frontalis
o Expression: Surprise
o Location: Either side of
forehead
o Function: Raises eyebrow
and wrinkles forehead
 Depressor anguli oris
o Expression: doubt,
disdain, contempt
o Location: along side of
chin
o Function: depresses
corner of mouth
 Orbicularis oris
o Expression: doubt, disdain,
contempt
o Location: ring-shaped muscle
found around mouth
o Function: compresses and
closes the lips
 Platysma
o Expression: horror
o Location: broad, thin muscular
sheet covering the side of
neck and lower jaw
o Function: draws corners of
mouth downward and
backward
Zygomaticus major
o Expression: laughing or
smiling
o Location: extends diagonally
upward from corner of
mouth
o Function: raises corner of
mouth
Nasalis
o Expression: flaring nostrils
o Location: over nasal bones
o Function: closes and opens
nasal openings
 Orbicularis
oculi
o Expression: sadness
o Location: Surrounds
eye orbit underlying
the eyebrows
o Function: Closes the
eyelid and tightens
the skin on the
forehead
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Masseter
o Location: Covers the
lateral surface of
mandible
o Function: Closes the jaw
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Temporalis
o Location: Located on the
temporal fossa of the
skull
o Function: Raises the jaw,
closes the mouth, and
draws back the jaw
Sternocleidomastoid
o Location: large muscles extending
diagonally down sides of neck
o Function: flexes head; rotates head
toward opposite side from muscle