Head and neck cranial nerves pt 2 Flashcards
What are the 3 branches of CN V?
ophthalmic - V1
maxillary - V2
mandibular - V3
where does the ophthalmic nerve exit?
superior orbital fissure
where does the maxillary nerve exit?
foramen rotunda
where does the mandibular nerve exit?
foramen ovale
what is it called when one branch of the trigeminal nerve becomes hypersensitive to pain? what is it often caused by?
trigeminal neuralgia
blood vessel pushing against affected nerve
Which branch is the only one that contains both sensory and motor axons?
mandibular nerve
for mastication
If the mandibular nerve was damaged, what are some observable signs?
demonstrable loss of bite strength
jaw deviating toward the lesioned side when mouth is actively open
What are some important functions of the facial nerve? (CN VII)
1) Six branches innervate muscles of facial expression
2) Sensory to some of the ear
3) Taste sensation to anterior tongue
3) Innervation to lacrimal, submandibular, and sublingual glands
If there was a lesion on one of the branches of the facial nerve, what could it de-innervate?
-temporal
-zygomatic
-buccal
-mandibular
-cervical
-posterior auricular
Paralysis or weakness to one side of the face is called ______
Bell’s Palsy
Peripheral CN VII
What would happen if there was a lesion centrally located within the cortex/brainstem?
Similar signs to Bell’s palsy but will have the ability to generate wrinkles to entire forehead, not partial
What muscle does the facial nerve innervate in the middle ear?
stapedius
The result of de-innervation of the stapedius muscle would result in _______: sounds are abnormally and painfully loud
hyperacusis
What are the 2 parasympathetic nerves of the facial nerve that innervate glands?
Greater petrosal nerve –> lacrimal nerve
Chorda tympani –> submandibular & sublingual glands
Besides loss of facial expression, what else can lesions to the facial nerve lead to? (hint: eyes, mouth)
De-innervation of:
lacrimal gland = dry eyes
submandibular & sublingual = dry mouth, altered taste sensations
What does vestibulocochlear (CN VIII) innervate?
organs of balance and hearing encased within temporal bone
What lesion or impingements can lead to altered equilibrium and hearing?
Very proximal facial nerve lesion
acoustic neuronma/schwannoma - both facial and vestibulocochlear nerve enter the skull through internal acoustic meatus
What are the 2 subdivisions of the vestibulocochlear called?
vestibular nerve (balance and equilibrium)
cochlear nerve (hearing)
What is the auricle (external ear) made out of?
hyaline cartilage
What is the auricle innervated by?
CN V3, VII, and upper cervical spinal nerves
What are the 3 ossicles of the middle ear?
malleus
incus
stapes
Describe the process of how we hear
1) sound waves push the tympanic membrane, moving the three ossicles of the middle ear
2) stapes pushes into the oval window of the inner ear
3) vibrations of the oval window stimulates the cochlea. The fluid inside moves which causes the basilar membrane to vibrate
4) The hair cells in the organ of corti of the cochlea responds to the movement of the basilar membrane, converting the waves into electrical signals
What are the semicircular canals filled of?
endolymph
How does the ear play a role in balance and equilibrium?
1) the inner ear senses head movement by the semicircular canals and otolith organs (utricle and saccule)
2) The ampulla of the semicircular canals detects rotational head movement. Inside is the cupula. As fluid moves, cupula deforms and stimulates sensory cilia to create nerve impulses sending to the brain via vestibular nerve
3) The otoliths move and shift the membrane, causing the hair cells to bend
4) bending of the hair cells create electrical signals which sends to the brain via vestibular nerve
