anatomy 4: cranial nerves function & innervation

5I 3-Scotland - prompts when considering aetiology

"3-Scotland" relates to the three top killers in Scotland. I: infection I: inflammation I: immune I: iatrogenic I: idiopathic 1: vascular/cardiovascular 2: cancer 3: trauma

oculomotor nerve palsy ('third nerve palsy')

'down and out' appearance of the affected eye ptosis mydriasis

presentation of oculomotor CNIII nerve palsy

'down and out' appearance of the affected eye ptosis mydriasis

vestibular testing

'unterberger' or 'turning test' - march on the spot with their arms outstretched and their eyes closed -> Vestibular lesion: the patient will turn towards the side of the lesion "Head thrust test" or "Vestibular-ocular reflex" - briskly turn head and ask patient to focus on your nose - patient with loss of vestibular function on one side, the eyes will first move in the direction of the head (losing fixation), before a corrective refixation saccade occurs towards your nose

nuclei of the parasympathetic cell column

Edinger-Westphal nucleus superior salivary nucleus inferior salivatory nucleus dorsal motor nucleus of the vagus

emergence of the accessory nerve

Emerges form the medulla, just posterior to the medullary olive

emergence of the hypoglossal nerve

Emerges from the anterolateral surface of the medulla, between the olive and the pyramid initially as a series of 10-15 rootlets which pass posterior to the vertebral artery Rootlets fuse as they enter the hypoglossal canal (small foramen in the occipital bone)

emergence of the vagus nerve

Emerges from the medulla oblongata of the brain stem as a series of rootlets just posterior to the medullary olive

classic description of seventh nerve palsy

Facial weakness with Bell's palsy typically involves the upper and lower portions of the face because nerve impairment is typically in the facial canal, proximal to the site where the nerve branches to distinct muscle groups in the face

fibres that run in the vestibulocochlear nerve

Fibres conveying the special senses of motion/positional sense and hearing

exclusively sensory cranial nerves

I II VIII

where are each cranial nerve found, broadly

I, II = cerebrum II-IV = midbrain V-VIII = pons VIII-XII = medulla

exclusively motor cranial nerves

III IV VI XI XII

cranial nerves that have parasympathetic innervation

III VII IX X

prolapsed IV disc most common where

L5 (most mobile area of spine)

causes of ansomia

Mucous blockage of the nose: preventing odours from reaching the olfactory nerve receptors. Head trauma: can result in shearing of the olfactory nerve fibres leading to anosmia. Genetics: some individuals have congenital anosmia. Parkinson's disease: anosmia is an early feature of Parkinson's disease. COVID-19: transient anosmia is a common feature of COVID-19.

cranial nerves & sympathetic innervation

None of the cranial nerves contain sympathetic innervation as that is thoraco-lumber outflow, however parasympathetic outflow is cranio-sacral

colour vision deficiencies

Optic neuritis: results in a reduction of colour vision (typically red). Vitamin A deficiency Chronic solvent exposure

features (function + location) of the infraorbital nerve

§ penetrates the maxilla on the floor of the orbit and emerges anteriorly via the infraorbital foramen § supplies sensory innervation to skin between the lower eyelid and upper lip, as well as the ala of the nose. § also provides branches into the maxilla - the superior alveolar nerves, that supply the maxillary teeth

features (function + location) of the zygomatic nerve

§ supplies sensation to the skin of the cheek and anterior temple § carries autonomic information, connecting the pterygopalatine ganglion with the lacrimal branch of the ophthalmic nerve

structure of the olfactory bulb/tract/stria

→ olfactory bulb thins posteriorly to become the olfactory tract → olfactory tract runs inferiorly along the base of the brain (frontal lobe) → as it approaches the brainstem, the olfactory tract divides into olfactory stria

cranial nerves that are both motor and sensory

V VII IX X

facial dermatomes the trigeminal nerve provides innervation to

V1 - ophthalmic V2 - maxillary V3 - mandibular

trigeminal nucleus

a large nucleus that runs the whole length of the brainstem and extends caudally into the cervical spinal cord

homonymous field defects

affect the same side of the visual field in each eye and are commonly attributed to stroke, tumour, abscess (i.e. pathology affecting visual pathways posterior to the optic chiasm) are deemed hemianopias if half the vision is affected and quadrantanopias if a quarter of the vision is affected

location at which the oculomotor nerve divides into a superior and inferior branch

anterior portion of the cavernous sinus

relevance of the facial dermatomes innervated by the trigeminal nerve

asses which part of the trigeminal nerve is affected by lesions → also relevant in Herpes Zoster infection

types of visual field defects

bitemporal hemianopia homonymous field defects scotoma monocular vision loss

emergence of the trigeminal nerve

brainstem on the lateral aspect of the pons

function of the tonsillar branch of the glossopharyngeal nerve

carries sensory fibres from the palatine tonsils

unilateral efferent defect

commonly caused by extrinsic compression of the oculomotor nerve = loss of the efferent limb of the ipsilateral pupillary reflexes ipsilateral pupil is dilated and non-responsive to light entering either eye (due to loss of ciliary sphincter function)

strabismus

condition in which the eyes do not properly align with each other when looking at an object

autonomic functions of the oculomotor nerve

control of pupil and lens - sphincter pupillae muscle - pupillary constriction - ciliary muscles - alter the curvature of the lens (allows eyes to focus)

formation of the optic nerve

convergence of axons from retinal ganglion cells → receive impulses from the photoreceptors of the eye

abducens CNVI nerve palsy

convergent squint

abducens nerve palsy ('sixth nerve palsy')

convergent squint horizontal diplopia affected eye turns medially

function of the oculomotor nucleus

efferent fibres run in the oculomotor nerve to innervate the levator palpebrae superioris muscle and all of the extraocular muscles, except the superior oblique and lateral rectus

emergence of the glossopharyngeal nerve

emerges as rootlets from the medulla and the posterolateral border of the medullary olive

function of the unique path of the superior oblique muscles

enables abduction, depression and internal/medial rotation of the eyeball

location at which afferent fibres carrying general sensory info from the head enter the brain/ terminate

enter at trigeminal nerve at level of pons terminate in trigeminal sensory nucleus

cranial nerve III (motor) function

eyeball movement elevation of the upper eyelid

testing cranial nerves III, IV, VI

eyelids - ptosis eye movements assessment of strabismus

cranial nerve VII (motor) function

facial movement tension on the bones of the middle ear

what occurs at the optic chiasm?

fibres from the nasal portion of each retina cross over to the other side, while fibres from the temporal portion of each retina remain on the same side → forms the optic tract, carrying contralateral visual information to the lateral geniculate nucleus of the thalamus

function of the trochlear nucleus

fibres leave in the trochlear nerve, to innervate the superior oblique muscle of the eye

location at which the mandibular nerve exits

foramen ovale in the sphenoid bone

emergence of the vestibulocochlear nerve

from the brainstem at the pontomedullary junction

fundoscopy

fundoscopy is performed to assess the optic disc for signs of pathology (e.g. papilloedema)

cranial nerve V (sensory) function

general sensation

cranial nerve IX (sensory) function

general sensation taste chemoreception baroreception

cranial nerve X (sensory) function

general sensation visceral sensation: chemoreception and baroreception

testing assessment vestibulocochlear nerve CNVIII

gross hearing assessment Rinne's test (tuning fork) Weber's test (tuning fork) vestibular testing

function of the nuclei of the branchiomotor cell column

innervates striated muscles derived from the embryonic branchial (pharyngeal) arches

function of the hypoglossal nucleus

innervates the intrinsic and extrinsic muscles of the tongue via the hypoglossal nerve

cranial nerve X (parasympathetic) function

innervation of cardiac muscle innervation of smooth muscle and glands of cardiovascular system, respiratory and GI tracts

hypoglossal nerve assessment CNXII

inspect tongue for wasting, deviation place finger on patient's cheek and ask them to push tongue against it - check for power imbalances

testing cranial nerve II

inspection of pupils -pupil size -pupil shape -pupil symmetry visual acuity -distance pupillary reflexes colour vision visual field blind spot fundoscopy

assessing function of glossopharyngeal nerve CNIX and vagus nerve CNX

inspection of soft palate and uvula swallow assessment gag reflex

stroke include weakness of the face, arm, and/or leg (pure motor stroke) most common cause

internal capsule infarct

location of the superior ganglion of the vagus nerve

jugular foramen (located between temporal bone (anteriorly) and occipital bone (posteriorly))

through which nucleus does each opic tract travel to the ipsilateral cerebral hemisphere?

lateral geniculate nucleus

features (location + function) of the facial motor nucleus

lies in the caudal pontine tegmentum innervates the muscles of facial expression and the stapedius muscle via the facial nerve

location of the hypoglossal nucleus

lies in the medulla

location of the trochlear nucleus

lies in the midbrain, at the ventral border of the periaqueductal grey, but at the level of the inferior colliculus

location of the oculomotor nucleus

lies in the ventral apex of the periaqueductal grey of the midbrain at the level of the superior colliculus

location and function of the somatic efferent cell column

lies near to the midline and consists of the nuclei that send motor fibres into the III, IV, VI and XII nerves

features (location + function) of the nucleus ambiguous

lies within the medulla long nucleus sends motor fibres into the glossopharyngeal, vagus and cranial part of the accessory nerve to innervate the muscles of the pharynx and larynx

location of the abducens nucleus

located in the caudal pons beneath the floor of the fourth ventricle

features (location + function) of the trigeminal motor nucleus

located in the tegmentum of the mid-pons supplies fibres to the trigeminal nerve and innervates the muscles of mastication, tensor tympani, tensor veli palatini, mylohyoid and the anterior belly of the digastric muscle

6 main branches of the glossopharyngeal nerve (has communicating branches with the vagus nerve, sympathetic trunk, and facial nerve)

tympanic nerve carotid sinus nerve pharyngeal branch (inferiorly) stylopharyngeal branch (after passing through superior and middle pharyngeal constrictor muscles) tonsillar branch lingual branch

testing cranial nerve I

using different odours (e.g. lemon, peppermint), or most formally using the University of Pennsylvania smell identification test

trochlear CNIV nerve palsy

vertical diplopia

trochlear nerve palsy ('fourth nerve palsy')

vertical diplopia 'up and out' appearance of affected eye

location at which afferent fibres carrying special senses of motion/positional sense and hearing terminate

vestibular and cochlear nuclei, respectively, which are located in the medulla, in and near to the lateral part of the floor of the fourth ventricle (sometimes referred to as the vestibular area)

cranial nerve VIII function

vestibular sensation (position and movement of the head) hearing

cranial nerve II function

vision pupillary light reflex

facial nerve palsy caused by LMN lesion presentation

weakness of all ipsilateral muscles of facial expression, due to the loss of innervation to all muscles on the affected side most common cause - Bell's palsy

function of the stylopharyngeal branch of the glossopharyngeal nerve

wraps around the stylopharngeus muscle, proving motor innervation

two branches of the maxillary nerve that travel laterally

zygomatic nerve infraorbital nerve

branches of the vagus nerve

Auricular n. Pharyngeal n. oesophageal plexus Superior laryngeal n (internal sensory, external motor) Cardiac branches Recurrent laryngeal n. anterior vagal trunk posterior vagal trunk

features of the accessory nerve

Collection of 4-6 rootlets which immediately join together to form one spinal accessory nerve It is joined by the spinal roots of other cervical nerves that have ascended through foramen magnum - theses nerves fuse as they travel across the floor of the occipital bone towards the jugular foramen - at the jugular foramen, a singular Accessory nerve exits provides somatic motor innervation to two muscles in the neck: sternocleidomastoid muscle and trapezius muscle

nuclei of the parasympathetic cell column function

Consists of preganglionic parasympathetic neurones that send axons into the III, VII, IX and X cranial nerves

branches of the mandibular nerve (that do not participate in the innervation of the dura in the anterior and middle cranial fossa )

nerve to the medial pterygoid anterior division posterior division

3 divisions of the efferent cranial nerve nuclei based on embryological derivation

nuclei of the somatic efferent cell column nuclei of the branchiomotor cell column nuclei of the parasympathetic cell column

location of termination of visceral afferents (inc taste fibres)

nucleus solitarius of the medulla

division of the vestibulocochlear nerve

occurs within the temporal bone -anterior trunk (cochlear) -posterior trunk (vestibular)

nuclei of the somatic efferent cell column

oculomotor nucleus trochlear nucleus abducens nucleus hypoglossal nucleus

retro-nasal olfaction

odorous molecules travel from the mouth, via the nasopharynx into the nasal cavity → contribute to our sense of taste

cranial nerve V (motor) function

opening and closing mouth tension on tympanic membrane

location at which optic nerve leaves bony orbit

optic canal - a passageway through the sphenoid bone

branches of the vagus nerve emerging from the inferior ganglion

pharyngeal branch superior laryngeal branch

visual field defects - what to think?

pre-chiasmic (optic nerve or eye, in which case would affect only one side) chiasmic (chiasmic field defect = bitemporal hemianopia) post-chiasmic

facial nerve palsy caused by UMN lesion presentation

presents with unilateral facial muscle weakness but upper facial muscles are partially spared because of bilateral cortical representation (resulting in forehead/frontalis function being somewhat maintained most common cause of upper motor neuron facial palsy is stroke

cranial nerve III (parasympathetic) function

pupillary constriction accommodation

cranial nerve IX (parasympathetic) function

salivation

cranial nerve VII (parasympathetic) function

salivation and lacrimation

facial nerve CNVII assessment

sensory assessment (taste) motor assessment (hearing, inspect face for asymmetry, facial movement)

assessment of trigeminal nerve CNV

sensory assessment - touch face motor assessment - mastication refkexes - jaw jerk, corneal

cranial nerve I function

smell

formation of the oculomotor nerve

somatic and visceral motor axons exit the brainstem on the anterior surface to form the oculomotor nerve

cranial nerve X (motor) function

speech swallowing

accessory nerve CNXI assessment

sternocleidomastoid or trapezius muscle wasting

through what does the oculomotor nerve enter the orbit

superior orbital fissure

through what does the trochlear nerve enter the orbit

superior orbital fissure

name and location of the specialised tissue for perceiving smell

superior surface of the nasal cavity is the olfactory epithelium

function of the branches of the terminal part of the facial nerve

supplies a subset of the muscles of facial expression around the eye, cheeks, mouth and neck

function of the hypoglossal canal

supply muscles involved in the movement of the tongue: the intrinsic muscles of the tongue, genioglossus muscle, geniohyoid muscle, styloglossus muscle, hyoglossus muscle, thyrohyoid muscle

function of nasopalatine nerve greater and lesser palatine nerves pharyngeal nerves

supply sensory information to the mucosa lining the nasal and palatine areas, as well as carrying autonomic input from the ganglion to the nasal, palatine and pharyngeal glands

facial nerve functions

supplying the muscles of facial expression supplementary role in: 1. receiving taste sensation from part of the tongue 2. the distribution of autonomic innervation to the salivary and lacrimal glands

cranial nerve IX (motor) function

swallowing

cranial nerve VII (sensory) function

taste

emergence of the trochlear nerve

the back of the brainstem, below the inferior colliculus

pathway the oculomotor nerve takes in order to reach the cranial cavity

the nerve runs anteriorly in the subarachnoid space, pierces the dura, and passes through the wall of the cavernous sinus into the cranial cavity

lower motor neurone disease presentation facial weakness

top and bottom of face affected

extracranial pathway of the ophthalmic nerve (further branching)

travels through the superior orbital fissure into the orbit where it divides into 3 further branches: frontal nerve lacrimal nerve nasocilliary nerve

at which structure do the roots of the trigeminal nerve come together

trigeminal ganglion; a flat, crescent shaped structure on the floor of the temporal bone, between the periosteal and meningeal dura

nuclei of the branchiomotor cell column

trigeminal motor nucleus facial motor nucleus nucleus ambiguous

distinct roots of the trigeminal nerve

- 2 distinct roots: o sensory (larger, carries information into the brainstem) o motor (smaller, located medially, carries information out of the brainstem into the periphery)

function of the pharyngeal branch of the glossopharyngeal nerve

- Carries general visceral sensory fibres from the oropharynx and surrounding mucosal membranes - Then unites with the Vagus nerve and the sympathetic trunk to form the pharyngeal plexus, supplying the muscles of the pharynx and soft palate

function of the lingual branch of the glossopharyngeal nerve

- Carries special sensory taste fibres from the posterior 1/3 of the tongue - Provides general sensation to the posterior 1/3 of the tongue

features of the meningeal branch of the vagus nerve

- Collects sensory information from the dura of the posterior cranial fossa - Contains a collection of sensory cell bodies from the meningeal branch and the auricular branch

features of the pharyngeal branch of the vagus nerve

- Courses superficial to the internal carotid artery and deep to the external carotid artery - Supplies a series of muscles in the pharynx: levator veli palatini, salpingopharyngeus, palatoglossus, palatopharyngeus, superior pharyngeal constrictor, middle pharyngeal constrictor, inferior pharyngeal constrictor - Also supplies the superior 1/3 of the oesophagus (striated muscle) - Purely motor information - Contributes to a pharyngeal plexus of nerves located posterior to the pharyngeal muscles - Muscles supplied are involved in swallowing

features of the 'nerve to the medial pterygoid' branch of the mandibular nerve

- Purely motor - supplies 3 muscles: /tensor veli palatini /medial pterygoid /tensor tympani

features of the auricular branch of the vagus nerve

- Travels across the posterior wall of the jugular foramen, through the temporal bone, and emerges posterior to the external acoustic meatus - Supplies sensory innervation to the auricle of the ear and the external acoustic meatus

features of the superior laryngeal branch of the vagus nerve

- Travels deep to the internal carotid artery - Carries motor and sensory innervation as it steeply descends from the inferior ganglion - Connections with the sympathetic chain in the neck, which sends small fibres along the superior laryngeal nerve to its targets in the larynx - Divides into internal and external branches - External branch innervates the cricothyroid muscle - alters the tension of the vocal cords, contributing to speech - Internal branch is primarily concerned with provided general sensory information to the mucosa of the larynx and pharynx above the vocal folds - Also carries special sensory information (taste) from the epiglottis

features of the posterior trunk (vestibular nerve) of the vestibulocochlear nerve

- after the division, the vestibular nerve passes through the vestibular ganglion (a collection of sensory nerve cell bodies - then divides into superior and inferior branches - both branches travel to the vestibular organ (comprised of three semicircular ducts, the utricle and the saccule) i. superior branch conveys sensory information from the anterior and lateral semicircular ducts, and the utricle ii. inferior branch innervates the posterior semicircular duct and the saccule - responsible for posture and balance

emergence of the facial nerve

- emerges from the lower margin of the pons where it meets the medulla oblongata below as two distinct roots: 1. the motor root / the facial motor root / facial nerve proper: carries motor neurones 2. the intermediate nerve: sensory and parasympathetic fibres

right recurrent laryngeal branch of the vagus nerve features

- from the Vagus nerve, just above the subclavian artery - travels inferiorly to hook underneath the subclavian artery - courses posteriorly and medially, to run in the tracheo-oesophageal groove where it ascends to the larynx

features of the lingual nerve of the 'posterior division' branch of the mandibular nerve

- lies in the medial wall of the ramus of the mandible → descends onto the floor of the oral cavity and passes under the submandibular duct - carries general sensation from the anterior 2/3rds of the tongue, along with autonomic fibres - transmits parasympathetic innervation from the submandibular ganglion to the submandibular and sublingual glands - carries taste sensation to the chorda tympani (a branch of the facial nerve)

features (location + function) of the inferior salivatory nucleus

- lies in the pontine tegmentum - parasympathetic cell group - sends preganglionic fibres into the glossopharyngeal nerve which terminate in the otic ganglion - the otic ganglion sends postganglionic axons to the parotid salivary gland

features (location + function) of the superior salivatory nucleus

- lies in the pontine tegmentum - parasympathetic cell group - supplies preganglionic fibres to the facial nerve that terminate in the pterygopalatine and submandibular ganglia - postganglionic fibres from the pterygopalatine ganglion innervate the lacrimal gland and the nasal and oral mucous membranes those from the submandibular ganglion innervate the submandibular and sublingual salivary glands

features (function + location) of the lacrimal nerve of the ophthalmic nerve

- located in the lateral orbit - supplies sensory innervation to conjunctiva, upper eyelid and lacrimal gland - carries autonomic parasympathetic fibres from the zygomatic nerve via a communicating branch to supply the lacrimal gland

features of the auriculotemporal nerve of the 'posterior division' branch of the mandibular nerve

- most posterior branch of the mandibular nerve - unique relationship with the middle meningeal artery and vein - the nerve commonly splits to encircle these vessels - primary function is to supply sensory innervation to the skin of the temple and the side of the head - also carries fibres from the lesser petrosal nerve via the otic ganglion to the parotid gland, providing parasympathetic innervation

features (location + function) of the Edinger-Westphal nucleus

- most rostral cell group - lies in the midbrain periaqueductal grey matter adjacent to the oculomotor nucleus - its axons leave the brainstem in the oculomotor nerve and pass to the ciliary ganglion in the orbit, within which they synapse; from here postganglionic fibres innervate the sphincter pupillae and ciliary muscles within the eye

left recurrent laryngeal branch of the vagus nerve features

- on the left, the Vagus nerve descends into the thorax before the recurrent laryngeal nerve diverges below the arch of the aorta - the nerve courses under the aortic arch, posterior to ligamentum arteriosum - it ascends in the trachea-oesphageal groove, where along with the right recurrent laryngeal nerve, it supplies the intrinsic muscles of the larynx except cricothyroid, - collects visceral sensory information, and supplies parasympathetic innervation to the larynx, oesophagus, and trachea along its course

smell detection

- sits on top of the cribriform plate of the ethmoid bone - holes in the cribriform plate house downward projections from the bulb, carrying them into the nasal cavity - at the end of these projections are cilia: hair like extensions at the terminal end of the olfactory sensory neurone - odorous particles dissolve in the mucus layer and stimulate the cilia - a signal is passed up via the dendrites and cell body to the axon of the olfactory sensory neurone → axon synapses with a mitral cell in the olfactory bulb - the mitral cell carries information back to the brain

features (location and function) of the dorsal motor nucleus of the vagus

- the largest preganglionic parasympathetic cell group - lies in the medulla - its rostral portion lies immediately beneath the floor of the fourth ventricle, lateral to the hypoglossal nucleus fibres leave in the vagus nerve and are widely distributed to thoracic and abdominal viscera

features (function + location) of the frontal nerve of the ophthalmic nerve

- travels along the roof of the orbit - supplies sensory information to the forehead and upper eyelids via its branches: the supratrochlear and supraorbital nerves

features of the anterior trunk (cochlear nerve) of the vestibulocochlear nerve

- travels towards the cochlea and coils up onto itself to form a spiral shape within the cochlear duct - the nerve makes contact with hair like cells in the cochlea, which convey auditory information about movement of the fluid in the cochlear duct - to the auditory cortex - responsible for hearing

features of the inferior alveolar nerve of the 'posterior division' branch of the mandibular nerve

- travels within the mandible, entering via the mandibular foramen and travelling in the mandibular canal - gives off short branches perceiving sensation from the mandibular teeth - terminal branches emerge from the mental foramen to supply the skin of the chin via the mental nerve - also has a motor branch supplying the mylohyoid muscle

assessing pupillary reflexes in testing of cranial nerve II

-direct (shining a light - observe for pupillary restriction in the ipsilateral eye) -consensual (contralateral eye) -swinging light test (move the pen torch rapidly between the two pupils to check for a relative afferent pupillary defect) -accommodation reflex

trigeminal ganglion features

-has its own extension of the meningeal dura, called Meckel's cave -unusual shape due to the large number of sensory nerve cell bodies located within it (analogous to the dorsal root ganglion) -only sensory cell bodies are located here; motor axons simply pass through - gives rise to 3 branches:

relative afferent pupillary defect (Marcus-Gunn pupil)

-normally light shone into either eye should constrict both pupils equally (due to the dual efferent pathways described above) -afferent limb in one of the optic nerves = damaged -> both pupils will constrict less when light is shone into the affected eye compared to the healthy eye -pupils, therefore, appear to relatively dilate when swinging the torch from the healthy to the affected eye

olfactory bulb features

-sits on top of the nasal cavity and has projections into the nasal epithelium below, which pick up different scents -the most anterior part of CNI -CNI is one of two cranial nerves which do not directly enter the brainstem (the other is the optic nerve) → instead, it communicates directly with the uncus, where info enters the olfactory cortex

features of the 'anterior division' branch of the mandibular nerve

/ also carries motor information to muscles of the face / branches to supply 3 muscles: - temporalis - lateral pterygoid - masseter / all of these muscles contribute to mastication / this branch also supplies sensory innervation to the inner cheek via the buccal nerve

autonomic innervation of the heart via the vagus nerve

1. deep cardiac plexus - located on the anterior surface of the distal trachea - supplied by the right Vagus nerve 2. superficial cardiac plexus - located below the aortic arch - supplied by the left Vagus nerve

branches of the maxillary nerve concerned with the nasal and palatine areas

1. nasopalatine nerve 2. greater and lesser palatine nerves 3. pharyngeal nerves

three branches of the trigeminal ganglion

1. ophthalmic (superior) - purely sensory 2. maxillary (middle) - purely sensory 3. mandibular (inferior) - motor and sensory information

ganglia of the glossopharyngeal nerve

1. superior ganglion in the jugular foramen 2. inferior ganglion below the exit of the jugular foramen

branches of the terminal part of the facial nerve

1. temporal nerve 2. zygomatic nerve 3. buccal nerve 4. mandibular nerve 5. cervical nerve

when LP for suspected SAH

12 hours after symptoms start (bilirubin formation)

causes of decreased visual acuity

Refractive errors Amblyopia Ocular media opacities such as cataract or corneal scarring Retinal diseases such as age-related macular degeneration Optic nerve (CN II) pathology such as optic neuritis Lesions higher in the visual pathways

function of the carotid sinus nerve of the glossopharyngeal nerve

Supplies the carotid sinus and body

features (function + location) of the nasocilliary nerve of the ophthalmic nerve

long ciliary nerves provide some sensory innervation to the cornea & transfer sympathetic innervation to the dilator pupillae muscles -short ciliary branches emerge from the ciliary ganglion -> provide sensory innervation to many of the internal eye structures & carry both parasympathetic and sympathetic innervation to the vessels and pupillary sphincter -nasocilliary nerve continues along the medial wall of the orbit -> two small nerves branch into the medial wall continue into the nasal cavity to supply sensory innervation to the facial sinuses and parts of the nasal mucosa -> terminal branches of the nasocilliary nerve and the infratrochlear nerve supply the lower eyelid, the bridge of the nose, conjunctiva, and lacrimal sac

Bitemporal hemianopia

loss of the temporal visual field in both eyes resulting in central tunnel vision. typically occurs as a result of optic chiasm compression by a tumour (e.g. pituitary adenoma, craniopharyngioma)

Composition of vestibulocochlear nerve

made up of two smaller nerves: vestibular nerve and cochlear nerve

branches of the superior ganglion vagus nerve as it exits the cranium

meningeal branch auricular branch

causes of funny turns

migraine TIA epileptic seizure dissociative/funcitonal

location of innervation of maxillary nerve

most extracranial has small meningeal branch, supplying the dura of the middle cranial fossa

initial branches of the ophthalmic nerve

most of its function is extracranial, but one small branch is given off before it leaves the cranial cavity: the tentorial branch → conveys sensation from the tentorium cerebelli

cranial nerve VI function

movement of eyeball

cranial nerve XI function

movement of head and shoulder

somatic functions of the oculomotor nerve

movement of the eye and eyelid - levator palpebrae superioris muscle - elevates the eyelid - superior rectus muscle - moves eyeball superiorly - inferior rectus muscle - depresses and adducts the eyeball - medial rectus muscle - adducts the eyeball - inferior oblique muscle - elevates, abducts and laterally rotates the eyeball

cranial nerve IV function

movement of the eyeball

cranial nerve XII function

movement of tongue