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Muscles of Facial Expression and Mastication (Chewing)

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Muscles of Facial Expression and Mastication (Chewing)

 

Muscles of Facial Expression

Blood Supply: External Carotid Artery
Motor Innervation: Facial Nerve (Vll)
Sensory Innervation: Trigeminal Nerve (V)

 

1)    Frontalis (worry muscle):

a.     Actions: Raises eyebrows, furrows brow
b.     Innervation: Facial Nerve (Vll)
c.     Origin: from galea aponeurotica
d.     Insertion: to skin above the eyebrows

 

2)    Occipitalis – not shown on diagram (in back):

a.     Actions: pulls scalp back
b.     Innervation: Facial Nerve (Vll)
c.     Origin: from posterior back of skull
d.     Insertion: to anteriorly with the galea aponeurotica

 

3)    Orbicularis oculi (sphincter muscle of the eyelid):

a.     Actions: squinting, closes eye, crowsfeet, eye bags
b.     Innervation: Facial Nerve (Vll)
c.     Origin/Insertion: surrounds rim of orbit

 

4)    Zygomaticus (major and minor) (smiling muscle):

a.     Actions: raises corners of mouth upward
b.     Innervation: Facial Nerve (Vll)
c.     Origin: from corners of mouth
d.     Insertion: to zygomatic bone

 

Risorius:
a. Actions: pulls laps laterally (helps with smiling)
b. Innervation: Facial Nerve (Vll)
c. Origin: from fascia of masseter
d. Insertion: to skin at corner of mouth

 

5)    Orbicularis oris (kissing muscle):

a.     Actions: closes lips, purses and protrudes lips
b.     Innervation: Facial Nerve (Vll)
c.     Origin/Insertion: surrounds mouth

 

6)    Mentalis (pouting muscle):

a.     Actions: protrudes lower lip, wrinkles chin
b.     Innervation: Facial Nerve (Vll)
c.     Origin: v-shaped pair from point of chin
d.     Insertion: to Orbicularis oris

 

7)    Buccinator:

a.     Actions: compresses cheeks for whistling, blowing and sucking (infants), holds food between teeth during chewing
b.     Innervation: Facial Nerve (Vll)
c.     Origin: from Orbicularis oris across cheek
d.     Insertion: back to maxilla and mandible by molars

 

8)    Platysma (grimace muscle):

a.     Actions: helps depress mandible
b.     Innervation: Facial Nerve (Vll)
c.     Origin: from mandible
d.     Insertion: to skin over clavicle

 

9)    Levator labii superioris:

a.     Actions: opens the lips and flares the nostrils
b.     Innervation: Facial Nerve (Vll)
c.     Origin: from the zygomatic arch and infraorbital margin of the maxilla
d.     Insertion: to the skin and muscle of the upper lip

 

10 ) Depressor anguli oris or Triangularis (frowning muscle):

a.     Actions: pulls corners of the mouth down
b.     Innervation: Facial Nerve (Vll)
c.     Origin: from corners of mouth
d.     Insertion: to mandible

 

11) Depressor labii inferioris (pouting muscle):

a.     Actions: pulls lower lip down down
b.     Innervation: Facial Nerve (Vll)
c.     Origin: from mandible
d.     Insertion: to the skin and muscle of lower lip

 

Clinical Significance:  Bell’s Palsy (Facial Nerve by ear)
Symptoms:

  1. Tearing (cannot blink, so irritation)
  2. Food collects in cheeks behind (buccinators paralyzed)
  3. Cannot whistle (Orbicularis oris paralyzed)

 

Muscles of Mastication (Chewing)

Blood Supply: Maxillary Artery (off External Carotid Artery)
Innervation: Trigeminal Nerve (V)

1)    Masseter:

a.     Actions: closes (elevates) mandible (powerful for chewing)
b.     Innervation: Trigeminal Nerve (V)
c.     Origin: from angle of mandible (cheek)
d.     Insertion: to zygomatic arch (lateral jaw)

 

2)    Temporalis:

a.     Actions: closes (elevates) mandible and retracts jaw
b.     Innervation: Trigeminal Nerve (V)
c.     Origin: from carotid process
d.     Insertion: to temporal bone

 

3)    Medial pterygoid (deep below zygomatic arch) – not shown on diagram:

a.     Actions: closes (elevates) mandible, side to side movement
b.     Innervation: Trigeminal Nerve (V)
c.     Origin: from sphenoid bone, maxilla and palatine bone
d.     Insertion: to medial (deep) mandible surface near angle

 

4)    Lateral pterygoid (deep below zygomatic arch) – not shown on diagram:

a.     Actions: protrudes mandible, side to side grinding, stabilizes temporal-mandibular joint
b.     Innervation: Trigeminal Nerve (V)
c.     Origin: from sphenoid bone
d.     Insertion: to the condyle of the mandible and the TMJ capsule

 

5)    Buccinator: though a muscle of facial expression, it also helps with chewing.
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