CRANIAL NERVES Flashcards
which cranial nerves arise from the cerebrum, while the rest arise from the brainstem?
I and II
describe the olfactory nerve
- CN I
- sensory - SVA
- special sense of smell
- attaches directly to forebrain and is extremely short
what are olfactory nerve fibres capable of?
regeneration
what is the olfactory nerve derived from embryologically?
olfactory placode ( a thickening of the ectoderm)
the olfactory nerves terminate in the olfactory bulb, by synapsing on what cells?
mitral cells
what kind of neurons are olfactory receptor cells?
bipolar
what are basal cells?
form new stem cells from which the new olfactory cells can develop
describe the lateral and medial stria
- Lateral stria – carries the axons to the primary olfactory cortex, located within the uncus of temporal lobe.
- Medial stria – carries the axons across the medial plane of the anterior commissure, where they meet the olfactory bulb of the opposite side.
where does the olfactory nerve leave the skull?
cribiform plate of the ethmoid
describe the optic nerve
> sensory
SSA
special sense of vision
attaches directly to forebrain
what is the optic nerve enveloped in?
meninges and CSF
what is papilloedema
sweeling/oedema of the optic nerve
- raised intracranial pressure givers rise to this as the optic nerve is enveloped in the meninges and CSF, therefore if the intracranial pressure increases CSF is pushed out into the eye
where does the optic nerve enter the skull?
optic canal
what modalities to CN III/IV/VI possess?
all motor, covering GSE
oculomotor also conveys GVE
where do CN III/IV/VI enter the skull?
superior orbital fissure
what does CN III do?
- provides motor innervation to 4 extraocular muscles — superior, inferior and medial rectus, and the inferior oblique
- also has parasympathetic fibres — synapse at ciliary ganglion and innervate the levator palpebrae superioris muscle (elevates eyelid)
CN III : motor neurons that serve the extraocular muscles have cell bodies where?
oculomotor nucleus
CN III : the preganglionic parasympathetic neurons that supply the levator muscle arise from where?
Edinger-Westphal nucleus
CN III/IV/VI pass in the lateral wall of what?
the cavernous sinus
what does CN IV do?
provides motor innvervation to the superior oblique
where are the cell bodies of CN IV?
trochlear nucleus
what is the only cranial nerve to emerge from the dorsal aspect of the brainstem?
CN IV (emerges just caudal to the inferior colliculus)
what does CN VI do?
provides motor innervation to the lateral rectus muscle
where are the cell bodies of CN VI? where is it located?
abducens nucleus = beneath 4th ventricle in caudal pons
name the 3 branches of the trigeminal nerve
V1 = ophthalmic
V2 = maxillary
V3 = mandibular
where do each of the divisions of the trigeminal nerve exit the skull?
V1 = SOF
V2 = foramen rotundum
V3 = foramen ovale
the trigeminal nerve is associated with derivatives of what?
the 1st pharyngeal arch
what does CN V supply sensation to?
general sensation in face, scalp, corneas and nasal and oral cavities, cranial dura mater
what does CN V supply motor innervation to?
muscles of mastication, tensor tympani
what nucleus is CN II associated with?
lateral geniculate nucleus
what are the branches of CN V1?
- frontal —> supratrochlear and supraorbital
- lacrimal —> sensory to lacrimal gland
- nasociliary
what supplies the frontal sinus?
surpaorbital nerve from V1
modality of V1
GSA
modality of V2
GSA
CN V2 exits the skull at the foramen rotundum and then enters what?
pterygopalatine fossa
what is the terminal branch of CN V2?
infraorbital nerve — infraorbital foramen
what branch of CN V2 exits via the incisive foramen?
nasopalatine
CN V3 exits through foramen ovale and enters what?
infratemporal fossa
the main trunk of the mandibular division gives off what before diving into ___ and ____ divisions?
- main trunk gives off the meningeal (S) and the medial pterygoid (M) branches before dividing into anterior and posterior divisions
what are branches of the anterior division of CN V3?
- buccal (sensory)
- deep temporal (motor)
- masseteric (motor)
- lateral pterygoid (motor)
what are the branches of the posterior division of CN V3?
- inferior alveolar (sensory)
- lingual (sensory)
- nerve to mylohyoid (motor)
- auriculotemporal (sensory)
what supplies the temporomandibular joint, skin of ear and external auditory meatus?
auriculotemporal branch of posterior division of CN V3
what are the 4 muscles of mastication?
masseter, temporalis, medial and lateral pterygoid
the mandibular division of CN V supplies motor innervation to 8 muscles. what are tehy?
4 muscles of mastication = masseter, temporalis, medial pterygoid, lateral pterygoid
also innervates anteiror belly of digastric, mylohyoid, tensor tympani and tensor veli palatini
sensory distribution of trigeminal nerve. what branch are the colours?
red - ophthalmic division
blue - maxillary division
green - mandibular division
what modalities does the facial nerve express?
SVE, GVE, SVA, GSA
the facial bone enters the petrous temporal bone via what?
internal auditory meatus
what does the facial nerve emerge from the temporal bone through?
stylomastoid formamen
what does the facial nerve run in in the petrous temporal bone?
facial canal
what branches does the facial nerve give off in the petrous temporal bone?
- greater petrosal = preganglionic parasympathetic fibres
- nerve to stapedius = motor
- chorda tympani = preganglionic parasympathetic and taste fibres
what are the 5 terminal motor branches of CN VII?
- temporal
- zygomatic
- buccal
- marginal mandibular
- cervical
what are the motor functions of CN VII? nucleus?
muscles of facial expression, stapedius
- facial motor nucleus
what is the sensory function of CN VII? nucleus?
- taste to anterior 2/3 of tongue
- nucleus solitaries
what are the parasympaethic functions of CN VII? function?
- salivary and lacrimal glands via submandibular and pterygopalatine ganglia
- superior salivatory nucleus
where do facial fibres carrying general sensation terminate? where do facial fibres carrying taste sensation terminate?
general sensation = trigeminal nucleus
taste = rostral part of nucleus solitarius in the medulla
where do preganglionic PS fibres of the lacrimal, nasal, submandibular ad sublingual glands arise?
superior salivatory nucleus of the pons
where does CN VIII enter the skull?
IAM
where does CN VIII enter the brainstem?
cerebellopontine angle
what modality does CN VIII convey
SSA
what nuclei are involved in CN VIII?
vestibular and cochlear nuclei
CN IX descends in the neck posterior to what?
stylopharyngeus = the only muscle this nerve supplies
what modalities does CN IX convey and what are its functions?
SVE - motor to stylopharyngeus
GVE - parasympathetic to parotid gland
GSA - general sensory to posterior 1/3 tongue, soft palate, fauces and oropharynx
GVA - sensory to carotid sinus and bodies
SVA - taste to posterior 1/3 tongue
where are the superior and inferior ganglia of CN IX and what do they contain?
- near the jugular foramen
- contain NCBs of 1st order neurons
CN IX supplies presynaptic fibres to what?
otic ganglion
psotganglionic PS fibres from teh otic ganglion provide secretomotor innervation to what?
parotid gland
where do preganglionic PS fibres to the parotid gland arise from?
inferior salivatory nucleus
where do the CN IX fibres carrying general sensation terminate?
trigeminal nucleus
what is the nucleus where visceral afferent fibres from the carotid sinus and bodies terminate?
nucleus solitaries
what is the nucleus where LMNs supplying the stylopharyngeus arise from?
nucleus ambiguous
what is the nucleus where glossopharyngeal nerve fibres carrying taste sensation terminate?
caudal end of nucleus solitaries
caudal vs rostral ends of nucleus solitaries
- facial fibres carrying taste sensation terminate in the rostral part of the nucleus solitarius of the medulla
- where glossopharyngeal nerve fibres carrying taste sensation terminate
where does the vagus nerve enter the skull?
jugular foramen
what modalities dos the vagus nerve convey?
SVE, GVE, GSA, GVA, SVA
the vagus nerve descends in what in the neck?
carotid sheath
what is in the carotid sheath?
- vagus nerve
- IJV
- common and internal carotid arteries
what reflex is the vagus nerve essential for?
cough
what do each of the modalities for the vagus nerve do?
SVE - motor to soft palate, larynx
GVE - parasympathetic to thoracic and abdominal organs
GSA - general sensory to inferior pharynx, larynx
GVA - sensory to aortic body and sinus, thoracic and abdominal viscera
SVA - taste to epiglottis
CN X :
afferent fibres for general sensation terminate in the___________, whereas visceral afferents terminate in the ________
- trigeminal sensory nucleus
- nucleus solitarius
CN X:
efferent fibres innervate muscles of soft palate, pharynx, larynx, and upper part of oesophagus. these fibres arise in the _____________ of the medulla
nucleus ambiguous
CN X:
parasympathetic fibres of the vagus nerve are distributed widely throughout the cardiovascular, respiratory and gastrointestinal systems — they arise at the ____________
dorsal motor nucleus of the vagus
where does the vagus nerve pass through the diaphragm?
T10 - oesophageal hiatus
what branches does CN X give off high within the neck?
pharyngeal branches — contribute motor fibres to pharyngeal plexus
what branches of CN X supply all the muscles of the larynx and provide sensory innervation to the larynx?
laryngeal branches
CN X : through its pharyngeal branches it supples what?
all the muscles of the soft palate except the tensor veli palatini and all the muscels of the pharynx except the stylopharyngeus
where does CN XI exit the skull?
jugular foramen
what modality do CN XI and XII convey?
GSE
what does CN XI supply?
trapezius and SCM
where does CN XII exit the cranial cavity?
hypoglossal canal
what does CN XII supply?
all the intrinsic and extrinsic muscles of the tongue except palatoglossus
what innervates palatoglossus?
pharyngeal branch of CN X
what does the carotid canal do?
transmits the internal carotid artery, internal carotid venous plexus and sympathetic nerve plexus in petrous temporal bone
what goes through foramen spinosum?
middle meningeal artery/vein and meningeal branch of the mandibular nerve
describe foramen lacerum
- filled with connective tissue
- crossed superiorly by the ICA
nucleus of XII?
hypoglossal nucleus
list the nerves with parasympathetic elements, their function and the nucleus involved
- III — Edinger-Westphal — pupillary constriction + accommodation
- VII — superior salivatory — salivation and lacrimation (via submandibular and pterygopalatine ganglia)
- IX — inferior salivatory — parotid gland (via otic ganglion)
- X — dorsal motor nucleus of vagus — thoracic and abdominal viscera
what runs in the walls of the cavernous sinus?
innervation of the tongue
- general sensation anterior 2/3 = trigeminal
- taste anterior 2/3 = facial
- posterior 1/3 sensation and taste = glossopharyngeal
- muscles = hypoglossal
gland innervation (parotid, sublingual, submandibular, thyroid)
- parotid = CN IX
- sublingual = facial (marginal mandibular)
- submandibular = facial (marginal mandibular)
- thyroid = vagus
describe the mental nerve
The mental nerve is a branch of the posterior trunk of the inferior alveolar nerve. This is a branch of the mandibular nerve (CN V3), itself a branch of the trigeminal nerve (CN V). It emerges from the mental foramen in the mandible.
The chorda tympani joins what nerve in the infratemporal fossa?
lingual
The chorda tympani exits the tympanic cavity through what?
the petrotympanic fissure
the proprioception pathway differs from other sensory pathways of the head how?
the nerve cell bodies of the primary neurones are located in the mesencephalic nucleus (i.e. the mesencephalic nucleus contains nerve cell bodies of primary neurones not secondary neurons).
innervation of digastric muscle
anterior belly = inferior alveolar nerve (branch of V3)
posterior belly = digastric branch of CN VII
innervation of stylohyoid? where does this nerve arise?
- stylohyoid branch of CNVII
- arises proximally to the parotid gland
