Download Muscles of facial expression

Muscles of facial expression
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Located in scalp, face, neck
No deep fascia in face -> skin moves with muscle, in body, skin moves over muscle.
o Muslces originate on bone and insert on skin, or other muscle -> NO TENDONS
1° fxn of face muscles = sphincters and dilators of face orifices, expression = 2°
Orbital -> closes eyelids, oral -> lips and mouth shape, nasal -> dilate nostrils, epicranial
-> wrinkle forehead, auricular -> animals for ear cocking
Cranial Nerves
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Muslces of face expression -> ALL 2ND PHARYNGEAL ARCH
o Supplied by CN VII
o CN VII -> 5 of 7 nerves types
o Primary root -> cell bodies in facial nucleus
 SVE (branchial motor) (muscles of face expression)
o Intermediate nerve
 motor -> cell bodies in superior salivatory nucleus
 GVE (to salivary glands)
 Sensory -> cell bodies in geniculate ganglion
 SVA (ant. 2/3 of tongue)
 GVA (nasal cavity and soft palate)
 GSA (parts of ear)
o primary root and intermediate root enter internal acoustic meatus separate, and
merge w/i meatus.
 Three branches b/f exiting the stylomastoid foramen
 greater petrosal n. -> GVE to lacimal and nasal glands
 nerve to stapedius -> SVE to stapedius muscle
 nerve to chorda tympani -> SVA from tongue, and GVE to
submandibular and sublingual glands
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facial nerve exits stylomastoid foramen -> parotid gland -> parotid plexus (hand thing on
neighbor)
o temporal
o zygomatic
o buccal
o marginal mandibular
o cervical
Parotid Gland
 largest of 3 salivary glands, has parotid sheath
 sensory inn. = (auriculotemporal n.) V3 and great auricular n. (C2, C3)
 motor (GVE) = CN IX (via auriculotemporal n.) (hitch a ride)
Bell Palsy – CN VII
 = unilat. Paralysis of face expression mm.
UMN and LMN
o upper part of facial nucleus -> upper face = bilat. Input from corticonuclear fibers
o lower part of facial nucleus -> lower face = only contralat. Input
 temporal bone fx -> damage to ANY level = FACIAL MUSCLE PARALYSIS
o level 1: internal acoustic meatus -> loss of hearing, balance, taste, and salivation
o level 2: loss of taste, lacrimation, salivation
o level 3 and 4: loss in taste and salivation
o level 5: loss in facial muscles only
Select Facial Muscles
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Orbicularis oculi -> around orbit
o Orbital part -> circles eye
o Palpebral part -> covers eyelids, closes eye gently
o LOF -> ptosis, fluid drips out, corneal ulcers
Orbicularis oris -> rims the lips, has 4 parts w/ stem at modiolus = hub at mouth corner
o Crossing fibers creates philtrum
o Whistling, kissing, pout
Buccinator -> forms substance of cheek.
o keeps cheeks taught. Prevents biting and keeps food together. Expels air. Smiles.
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o LOF = drooping of mouth corner. Food and saliva dribbles out. Keeps food out of
vestibule.
Zygmaticus Major -> elevates labial commissures. Smile and sneer.
Arteries and Veins and Lymphatics
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Blushing and blanching.
From internal and external carotid.
facial artery -> from external carotid
o termiantes as angular artery alongside nose
o can take pulse with it. Anterior to masseter.
o Also temporal pulse
Facial vein = main vein of face
Triangular danger zone = facial veins to dural venous
sinuses
Superficial drainage of face = pericervical collar of nodes
Deep drainage = deep cervical nodes along jugular
Muscles of Mastication
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They act on the TMJ joint, located in the temporal and
infratemporal fossae
TMJ
 = synovial joint. Articulation b/t head of mandible and mandibular/glenoid articular
fossa.
 Articular surfaces = lined with fibrocartilage rather than hyaline. Withstands shear stress,
but more susceptible to hormonal fluctuations -> deterioration.
 Superior articular and inferior articular cavities divided by articular disc
o A.d. attached to joint capsule, condyle, and muscle
 Mod. Hinge joint -> gliding, hinge act, and pivot
o Upper jt capsule = loose (gliding)
o Lower jt capsule = tight (hinge and some pivot)
 Chewing involves elevation/depression, protraction/retraction, and medial/lateral
excursion
 Closed mouth to 15 degrees = only hinge action at inferior jt capsule
 Open mouth >15 degrees = combined gliding of mandibular heads
o Involves depression and protraction
 Grinding movements
o resting condyle -> pivots or rotates horizontally
o swinging condyle -> swings/glides anteriorly
 There is a physiologic normal dislocation
 Dislocation could be pathologic as well
TMJ Muscles
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Masseter = primary mashing, some protrusion
Temporalis = along cranium. Drives lower jaw into upper jaw. Up and back pull.
Retrusion.
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Pterygoids, medial and lateral plates
o Protrusion, eleveation, side to
side movement
o Lateral -> lateral direction
 Upper -> insert on TMJ
capsule
 Lower -> insert on
condylar process
o Medial -> creates sling w/
masseter
 two heads, deep and superficial
o bilateral action -> elevates mandible
o unilateral action -> smaller grinding movements
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Depression of mandible -> gravity, suprahyoid, infrahyoid, platysma, and lat. Pterygoid
CN V
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Trigeminal nerve. 4 fiber types.
GSA
SVE
Pathway… for SVA (taste on tongue via lingual n.)
Pathway…for GVE (salivary glands via lingual n.)
Emerges from Pons as
o Sensory root
 Mesencephalic nucleus = proprioception
 Principal/pontine sensory nucleus = touch
 Spinal nucleus = pain, temps, touch
o Motor root -> cell bodies in trigeminal motor nucleus
Most of trigeminal ganglion = sensory nuclei
o Housed in trigeminal cave
o 3 peripheral processes of trigeminal ganglion = 3 divisions
 V1 -> out sup. Orbital fissure, somatic sensory to orbit
 Branch exits supraorbital notch
 V2 -> out foramen rotundum, somatic sensory to upper jaw
 Branch exits infraorbital notch
 V3 -> out foramen ovale, somatic sensory to lower jaw
 Motor to muscles of mastication
 Branch exits mental foramen
Trigeminal nerve = nerve of 1st pharyngeal arch
o Muscles of mastication (V3)
 V3 branches include
 Lingual n.
 Mandibular n.
 Buccal n.
Blood Supply
 Maxillary artery -> from external carotid. Three parts: 1 -> 2 -> 3
o 1) Mandibular
 inferior alveolar
 middle meningeal
o 2) Pterygoid
 buccal artery
 deep temporal branches
o 3) pterygopalantine