Gross Anatomy U4L32

what nerve innervates the muscles of facial expression

facial nerve (CN VII) via the parotid plexus

describe the pathway of the facial nerve (CN VII)

exits stylomastoid foramen via internal acoustic meatus, middle ear

regional groups of the face

orbital

oral

nasal

“other”

facial nerve pathway

exits stylomastoid foramen via internal acoustic meatus (middle ear)

facial nerve branches from superior to inferior

temporal

zygomatic

buccal

marginal mandibular

cervical

orbital group muscles

corrugator supercilli

orbicularis oculi (orbital, palpebral and lacrimal parts)

orbicularis oculi

close the eyelids

orbital part of orbicularis oculi

strong closure of eye

palpebral part of orbicularis oculi

gentle closure of eye, wink

lacrimal part of orbicularis oculi

facilitates tear pump into lacrimal sac

corrugator supercilli

draws medial eyebrows inferomedially, stern expressions

oral group of facial muscles

levator labii superioris

levator labii superioris alaeque nasi

zygomaticus major

zygomaticus minor

risorius

buccinator

levator anguli oris

depressor anguli oris

depressor labii inferioris

mentalis

orbicularis oris

levator labii superioris

elevates upper lip

levator labii superioris alaeque nasi

elevates upper lips and dilates nostril

zygomaticus minor

elevates upper lip

zygomaticus major

pulls mouth superolaterally when smiling

risorius

widens mouth transversely

buccinator

pulls cheeks medially, compresses against teeth, sucking

levator anguli oris

elevates upper lip at an angle

depressor anguli oris

depresses lower lips outwardly at an angle

depresor labii inferioris

depresses lower lip

mentalis

curls, protrudes lower lip

orbicularis oris

closes mouth, purses and protrudes lips, kissing muscle

nasal group muscles

nasalis

depressor septi nasi

procerus

other facial muscles

auricular muscles

platysma

occipitofrontalis

• frontalis part

• occipitalis

nasalis

compressor nasalis: compresses the nostrils

dilator nasalis: dilates nostrils

depressor septi nasi

anteriorly draws nasal septum and aids in constricting nostrils medially

procerus

wrinkles the skin of the upper bridge of the nose

auricular muscles

surrounds the ears, rudimentary, in dogs they move ears to locate sound

platysma

wrinkles the neck skin

occipitofrontalis

wrinkles skin of each respective area and moves the scalp anteriorly-posteriorly in tandem

frontalis: raises eyebrows and pulls scalp anteriorly

occipitalis: pulls scalp posteriorly

bell’s palsy

when muscles on one side of the face area weak or paralyzed due to damage to the facial nerve

damage or surgery to parotid gland can injure nerve as it travels through the gland

drooping face only on side affected

problems with expressions, pain, drooling, sensitivity on the side

parotid gland

superficial and deep regions with facial nerve demarcating that boundary

sympathetic innervation of parotid gland

vasoconstriction, reduces saliva secretion

presynaptic: sympathetic trunk

synapse: superior cervical ganglion

postsynaptic: travels with external carotid artery to parotid gland

parasympathetic innervation of parotid gland

induces secretion of saliva

presynaptic: tympanic nerve enters tympanic cavity and exits as lesser petrosal

synapse: otic ganglion

postsynaptic: auriculotemporal nerve to parotid gland

general sensory afferent of parotid gland

auriculotemporal nerve

what structures are associated with the parotid gland

facial nerve: passes through it

retromandibular vein: deep part of parotid gland, located posteriorly

external carotid artery: pass posteriorly

• posterior auricular artery

• superficial temporal artery

• maxillary artery

frey’s syndrome/auriculotemporal syndrome

results from parotid gland injury or surgery

postsynaptic parasympathetic nerves and sympathetic nerve fibers re-wire

causes parasympathetic n wanting to produce saliva via parotid gland but instead activates sweat glands, while sympathetic activates secretion of saliva

the scalp

skin: follicles, sweat, sebaceous glands

dense connective tissue: fat, CT, blood vessels

aponeurosis: occipitofrontalis

loose connective tissue: allows movement, potential space

pericranium: periosteum attaches to skull

scalp bleeding

deep connective tissue

aponeurosis, muscles, connective tissues are pulled taut with occipitofrontalis tension

scalp keeps bleeding with injury, important to get under control

motor innervation of skin of face and scalp

facial muscles

anterior cutaneous sensory innervation of skin of face and scalp

trigeminal divisions: ophthalmic, maxillary, mandibular

posterior cutaneous sensory innervation of skin of face and scalp

cervical spinal nerves C2,3

location order anterior to posterior of ophthalmic divison

supraorbital n

supratrochlear n

infratrochlear n

external nasal branch of anterior ethmoidal n

location order anterior to posterior of maxillary

zygomaticotemporal

zygomaticofacial

infraorbital

location order anterior to posterior of maxillary

auriculotemporal n

buccal n

mental n

location order anterior to posterior dorsal rami cervical spinal nerves

greater occipital n

3rd occipital n

location order anterior to posterior cervical plexus nerve branches (ventral rami)

lesser occipital n

great auricular n

transverse cervical n

supraclavicular n

trigeminal neuralgia (tic douloureux)

unknown origin

compression of trigeminal nerve in cranial cavity by superior cerebral artery

sensitive touch triggers sharp pain

V2, V3, V1

“suicide disease”