Cranial nerves 2 Flashcards
what neurons are in V trigeminal nerve ?
.mainly sensory with some motor
. sensory because it is the principal somatic sensory ( touch , pain , temperature/thermal ) nerve for face and head
. motor just supplies muscle of mastication ( chewing )
why it called trigeminal nerve ?
. because there are 3 major nerves that come together to form the trigeminal nerve
. 3 separate nerve divisions
ophthalmic divison - goes through superior orbital fissure( V1)
maxillary ( V2 )
mandibular ( V3 )
-each of these 3 branches of trigmenial either enter or exit through 3 separate holes in the skull.
. 3 separate foramens 1 for each division : superior orbital fissure(ophthalmic) , foramen rotundum (maxillary) , foramen ovale respectively (mandibular)
what are the 3 trigeminal divisions location and function ?
- ophthalmic : somatic sensation skin of forehead , upper eyelid + cornea surface and inside the eye
- maxillary : from skin of the lower eyelid , cheek + upper teeth and nasal mucosa
- mandibular : from skin and teeth of lower jaw + tongue and also contains motor output to the chewing muscles
what is test of ophthalmic nerve function ?
corneal - eyeblink reflex
what neurons innervate facial nerve VII?
-Has 3 compositions a nerve could have
- mixed sensory , motor and autonomic
.sensory : from taste buds on anterior 2/3 of tongue ( sweet , sour , salt )
. parasympathetic : supplies the lacrimal gland ( tear production ) via pterygopalatine ganglion + submandibular and sublingual salivary glands via the geniculate ganglion
foramen : internal auditory / acoustic meatus
what is main function of facial nerve VII ?
runs form main motor nucleus which supplies to muscles of facial expression including some near the eye
e.g. orbicularis oculi and frontalis
what does facial nerve pass through ?
internal auditory meatus
what is the functions of orbicularis oculi ?
it closes the eyelids when you blink spreading the tear film over the cornea to keep it hydrated , thus preventing cornea dehydration and prevents cornea cracking which can cause cornea to go opaque and cause blindness
what happens when you damage in VII facial nerve ?
causes a conditions called bell’s palsy
how to test if someone has a bell’s palsy ?
ask them to look up and show teeth
if there is a dropping eyelid along with weakness or total paralysis on one side of the face and can’t close eyes that means that they may have bell’s palsy along
how to treat upper eyelid palsy ?
insert gold weight
. eye kept open by voluntary contraction of LPS muscle
. relax LPS , eye closes by force of gravity
how to treat eveted lower eyelid ?
tighten surgically
. creates a lateral pool of tears
. reduce lower lid length and prevents drooping
how to treat dry eye ?
lubricating drops or ointments
. moisture chamber shields attached to spectacle frames , lessens tear evaporation
what nerves innervate VII vestibulo-cochlear ?
pure sensory , originates from ear
what are two different components of VII vestibulo - cochlear ?
. cochlear nerve : carries hearing / auditory information
. vestibular nerve : carries information regarding the position and movement of the head
what is the foramen for VII vestibulo - cochlear ?
nerves leave via internal auditory / acoustic meatus
what is example of vestibular dysfunctions ?
loss of VOR and oscillopsia
what is the function of outer and middle ears ?
convert and amplify air pressure ( sound ) waves at ear drum and via the ossicles into mechanical movement of auditory receptors ( hair cells ) in the cochlea ( inner ear ) innervated by spiral ( cochlea ) ganglion cells
-cochlea sits close to a bone outside your head- called mastoid process
What are the simple tests of auditory function ?
- using an Otoscope/auriscope
- Audiometry: detecting different sound frequencies
What are the 3 different results fo the tests for auditory function?
-Normal Audible Frequency Range: 20Hz (bone vibration) to 20kHz
Amplitudes: 30dB (whisper); 60dB (normal conversation); 120 dB (aircraft)
-(1) Conductive hearing loss: affects outer or middle ear
common, mild/moderate (5-30dB), usually reversible (ear wax, ‘glue ear’)
sound detection via mastoid bone conduction will be unaffected
-(2) Sensory-neural hearing, hair cell damage: severe & irreversible
excess noise exposure; antibiotics (-cillins); age-related (presbycusis)
sound detection via mastoid bone conduction will also be absent
What happens if you activate the bone of the mastoid process?
- it will vibrate and the stimuli through bone vibration will travels directly to cochlear, by passing the outer and middle ear
- and cause hair cells to be distorted and pick up sound.
What are the 2 components related to the 8the nerve ?
-1. Vestibule (a.k.a. 2 Otolithic organs)
Utricle & Saccule
Hair cells monitor head position with respect to gravity
Test of function; Eye-righting reflex
Eyes rotate with head tilt
-2. 3 Semi-circular Canals
Horizontal, posterior, anterior
- have Hair cells which monitor angular head acceleration & deceleration in 3D space
Test of function; Vestibular-Ocular Reflex (VOR)
Eyes move opposite to head turn
What is the IX Glossopharyngeal (9) nerve?
-Mixed sensory, motor & autonomic
-Sensory: somatic sensation from pharynx & posterior 1/3 of tongue + taste buds (bitter)
Parasympathetic: to Otic ganglion which supplies the parotid salivary gland
What is the main function of IX Glossopharyngeal (9) nerve?
-Main function is voluntary motor( bit which arrises from a nucleus in your medulla of your brainstem),called = Nucleus Ambiguous send out axons to innervate stylopharyngeal muscles which elevate larynx to allow swallowing when contracted.
What is the foramen for the IX Glossopharyngeal (9) nerve?
jugular foramen
What is the test for the motor function of the IX Glossopharyngeal (9) nerve?
Test of motor function: ‘gag’ reflex
What is the X vagus nerve?
- Mixed sensory, motor & autonomic
- Sensory: somatic (pain, thermal,pressure,temp) from these same regions & from (all the organs inside your body) thoracic + abdominal organs
What is the X vagus nerve main function?
Main function, from Nucleus Ambiguous to muscles of pharynx, soft palate & larynx controlling swallowing & speech (recurrent laryngeal nerve to vocal cords)
-Important in controlling the movements of your vocal apparatus allowing you to talk.
What is another main function of the X vagus nerve?
Another Main Function= Parasympathetic component which is massive, widespread to all thoracic + abdominal organs (for resting, digesting)
nucelus in medulla send axons out to a bunch of different ganglia in thorax and abdomen - resting and digestion
What is the foramen for the vagus nerve?
Foramen: jugular foramen
What are the tests for the motor function of the X Vagus nerve?
lesions of recurrent laryngeal nerve results in hoarse speech
What does the vagus nerve pass through?
jugular foramen
What is X| accessory nerve?
-Pure motor, 2 Divisions
-Innervates 2 voluntary muscles (sternocleidomastoid and trapezius )
-Larger = mainly supplies sternocleidomastoid (rotates head away) & trapezius (lifts shoulders) muscles
Smaller = some input to internal laryngeal & soft palate for speech production
What is the foramen for the accessory nerve?
jugular foramen & foramen magnum
What do the lesions in the accessory nerve cause?
difficulty in rotating the head towards the opposite side (sternocleidomastoid) & in elevating the shoulder on the affected side (trapezius
What is the X|| hypoglossal nerve?
- Pure motor
- Hypoglossal Nucleus supplies intrinsic and extrinsic muscles of the tongue, movement for eating & speech production
What is the foramen for the X|| hypoglossal nerve?
hypoglossal canal
What are the lesions characterised by in the X|| hypoglossal nerve?
-by ‘fasciculation’ of intrinsic muscles (spasms, twitching) on the affected side & deviation towards the affected side on tongue extension due to paralysis/ weakness of extrinsic muscles
What is the difference between intrinsic and extrinsic muscle?
rolling your tongue- contracting muscle inside tongue.
-poking tongue out- id contracting muscles underneath tongue and protruding it out of your mouth
-Different motor neurons in the hypoglossal nucleus will innervate intinstic or extrinsic muscles.
Where does the hypoglossal nerve pass through?
hypoglossal canals ( near foramen magnum)
What are the effects of someone having their right hypoglossal nerve lesion (damaged)?
-When poking tongue out it can’t protrude to the right side - moves to weakened side/ protrudes to direction of where the nerve is damaged and left side is good.
What ganglia cells directly innervate the lacrimal gland?
pterygopalatine- hearing
