Cranial Nerves - Prof Rea Flashcards
what are the 12 cranial nerves
olfactory
optic
oculomotor
trochlear
trigeminal
abducens
facial
vestibulocochlear
glossopharyngeal
vagus
spinal accessory
hypoglossal
what is the first cranial nerve
olfactory
what is the second cranial nerve
optic
what is the third cranial nerve
oculomotor
what is the fourth cranial nerve
trochlear
what is the fifth cranial nerve
trigeminal
what is the sixth cranial nerve
abducens
what is the seventh cranial nerve
facial
what is the eighth cranial nerve
vestibulocochlear
what is the ninth cranial nerve
glossopharyngeal
what is the tenth cranial nerve
vagus
what is the eleventh cranial nerve
spinal accessory
what is the twelfth cranial nerve
muscles of the tongue
what are the three main functional components of the cranial nerves
motor innervation to voluntary muscles
motor innervation to involuntary muscles
sensory
describe the motor innervation to voluntary muscles by cranial nerves
can either be somatic motor or branchial motor
which of the voluntary muscle innervations come from the pharyngeal arches
branchial motor
what are the involuntary muscles provided by the cranial nerves
sphincter papillae and lacrimal glands
describe the sensory component of cranial nerve innervation
sensation from the viscera, general sensation and special senses
what does the sphincter pupillae do
constrict the pupil
what do the lacrimal glands do
tear production
what are the pharyngeal arches remnants of
gills because we evolved from fish
why do pupils constrict in bright light
to protect the back of the retina
what is general sensation
touch pressure temperature and pain
what are special senses
taste
smell
sight
hearing
balance
which nerve fibres are capable of regeneration
olfactory
what are olfactory ensheathing cells used for
used in spinal cord injury patients to enable them to regain some function
what is anosmia
no smell
what can be injected into the patients with spinal cord injuries
olfactory ensheathing cells
describe the function of the olfactory nerve
special sensory for smell from the nasal mucosa of each nasal cavity, nasal septum and superior conchae.
has olfactory epithelium
describe the function of the optic nerve
special sensory for vision.
the nerve cell bodies are found in the retina and exit the orbital canal via the optic chiasm.
vision comes from the retina
what is multiple scelorosis
a demyelinated disease which can lead to disrupted vision
what is the optic chiasm
the crossing point of fibres of the left and right optic nerves.
some fibres stay on the same side, others cross over, and this happens at the chiasm.
what is myelin
fatty sheath that surrounds the axons of the nerve fibres.
how can MS affect vision
results in loss of myelin and this can result in weakness of the limbs and reduction of sight
in severe cases there can be complete loss of vision as the axon of the optic nerve is surrounded by myelin
which cranial nerve is a direct extension of the brain
the optic nerve
what are the extra ocular muscles
muscles that surround the eye and are responsible for movement of the eyeball itself
describe the sphincter pupillae
smooth muscle that constricts the eye as part of the pupillary light reflex
what does the ciliary muscle control
accommodation ie looing at far or near objects and focusing on things. it alters the shape of the lens, but not the pupillary size.
which muscles control pupil size
sphincter pupillae and dilatory pupillae
what is the ciliary ganglion
this is where the presynaptic and post synaptic fibres synapse.
where are the parasympathetic fibres of the eye distributed to
the sphincter pupillae and ciliary muscle
what can cause compression of the oculomotor nerve
aneurysm
diabetes
inflammation
trauma
what does the inferior oblique muscle do
move the eye upward and outward
what does the levator palpebrae do
hold the eyelids open
what does the medial rectus do
move the eye toward the nose
what does the ciliary muscle allow the eye to do
look both into the distance and close up
what are the muscles provided by the oculomotor nerve
superior rectus
medial rectus
inferior oblique
levator palpebrae superiosis
what delivers the parasympathetic innervation to the sphincter pupillae and ciliary muscle
the ciliary ganglion
what does raised intracranial pressure lead to
compression oculomotor nerve
describe the trochlear nerve
cell bodies of this nerve are located in the midbrain
deliver motor innervation to the superior oblique
it is rarely paralysed on its own
what is diplopia
double vision
what is the main role of the superior oblique muscle
medial rotation, as well as abducting the eyeball and repressing it. can be found to move the eye down and outward
what are the clinical presentations of diplopia
patient complaining of dizziness and lightness on their feet
describe the opthalmic division of the trigeminal nerve
general sensation from:
- cornea
- scalp
- eyelids
- nose
- mucosa of nasal cavity
- paranasal sinuses
describe the maxillary division of the trigeminal nerve
general sensation from:
- maxilla
- upper lip
- maxillary teeth
- maxillary sinuses
what nerve supplies the maxillary teeth
the superior alveolar nerve, from the maxillary branch of the trigeminal nerve
what are the maxillary sinuses
air filled cavities within the maxillary bones of the skull that help to lighten the skull and provide vocal resonance
describe the mandibular division of the trigeminal nerve
general sensation from:
- side of the mandible
- mandibular teeth
- mucosa of the mouth
- anterior two thirds of the tongue
what nerve supplies the mandibular teeth
inferior alveolar nerve, from the mandibular division of the trigeminal nerve
what does the masseter do
elevate the mandible
describe the attachments of the masseter muscle
extend from the zygomatic arch to the angle and ramus of the mandible
describe the attachments of the temporalis muscle
parietal bone and the sphenoid bone to the coronoid process of the mandible
what does the temporalis muscle do
elevate and retract the mandible
describe the attachments of the lateral pterygoid
sphenoid bone and the lateral pterygoid plate to the condyle of the mandible
what does the lateral pterygoid do
protrudes the mandible and is involved in side to side movement of the mandible
what does the medial pterygoid do
elevation of the mandible, aid closure of the jaw, assist in lateral pterygoid muscle in side to side movement of the jaw
describe the attachments of the medial pterygoid
lateral pterygoid plate, palatine bone, and maxillary tuberosity to the medial angle of the mandible
label this
label this
where in the brain does the abducens arise
the pons
describe where the trochlear nerve arises from
midbrain
what does the abducens nerve do
innervate somatic motor to the lateral rectus
what does the lateral rectus do
abduct the eyeball - look laterally
describe the clinical problem associated with abducens nerve
can be stretched in raised intracranial pressure due to a bleed or trauma, leading to the patient not being able to move their eye laterally on the affected side, and it typically is medially rotated
what is LR6 SO4
mnemonic to aid recall of motor innervation in the eyes.
lateral rectus supplied by CN6, abducens
superior oblique supplied by CN4, trochlear
describe the branchial motor function of the facial nerve
motor innervation to the muscles of facial expression, scalp, stapedius
describe the special sensory innervation of the facial nerve
taste to anterior two thirds of the tongue and palate
describe the visceral motor innervation of the facial nerve
parasympathetic innervation to the submandibular and sublingual glands
salivary glands, lacrimal glands and glands of the nose and palate
how many facial expression
43
what do the muscles of facial expression come from
the second pharyngeal arch
how does the facial nerve enter the face to innervate it
through the stylomastoid foramen
what happens if the stapedius muscle doesnt work
sounds appear louder
describe the function of the vestibulocochlear nerve
vestibular sensation from the semicircular ducts
hearing from the spinal organ
describe internal acoustic neuromas
slow growing benign tumours which slowly develop over the years
can cause loss of hearing and altered balance, and ringing in the ears
larger ones can cause headaches, double vision, numbness and weakness on one side of the face
what does the spiral organ provide
hearing
what do semi circular canals provide
vestibular sensation
list the functions of the glossopharyngeal nerve
somatic motor
visceral motor
visceral sensory
special sensory
somatic sensory
describe somatic motor function of the glossopharyngeal nerve
motor to stylopharyngueus
describe the visceral motor of the glossopharyngeal nerve
parasympathetic innervation to the parotid gland
describe the visceral sensory function of the glossopharyngeal nerve
parotid gland
pharynx
middle ear
describe the special sensory function of the glossopharyngeal nerve
posterior one third of the tongue
describe the somatic sensory innervation of the glossopharyngeal
external ear
what does the stylopharyngeus do
this is the only muscle of the pharynx that is innervated by the glossopharyngeal nerve, and it raises the larynx and pharynx and dilates the pharynx to enable flood to pass down, thereby inhibiting swallowing
describe the somatic motor innervation of the vagus nerve
muscles of the pharynx
intrinsic muscles of larynx
muscles of palate
muscle in upper two third of the oesophagus
describe the vagus nerves visceral motor function
parasympathetic innervation to the trachea, bronchi, gastrointestinal tract, and the heart
describe the vagus nerve
the wandering nerve
describe the visceral sensory function of the vagus
tongue, larynx, respiratory tract, heart, upper gi tract to the left colic flexure
describe the special sensory function of the vagus nerve
epiglottis and the palate
describe the general sensory function of the vagus nerve
auricle
external auditory meatus
describe the clinical test for the cranial nerves IX and X
ask the patient to say ahh and watch the uvula at the back of the mouth. if there is palsy of either nerve, the uvula will be pulled to the unaffected side
describe the function of the spinal accessory nerve
somatic innervation to the sternocleidomastoid and trapezius muscle
describe the attachments of the sternocleidomastoid muscle
mastoid process behind the ear, to the clavicle and the sternum
how to test for the spinal accessory muscle
test the trapezius and sternocleidomastoid contraction with and without resistance on the patient
describe the function of the hypoglossal nerve
somatic motor innervation to the intrinsic and extrinsic muscles of the tongue except for the palatoglossus
what supplies the palatoglossus
the vagus nerve
how to test the hypoglossal nerve
ask the patient to stick out their tongue and it should be symmetrical when coming out. if there is palsy, the tongue would stick out to the affected side due to unopposed action of the normal side of the tongue
how to test the first cranial nerve
ask the patient to smell toothpaste or coffee, and ask if they notice any changes in smell
describe the test for vision
pupil dilation using a torch, ask the patient to read a document provided they have glasses if they need them
describe the test for oculomotion
follow your finger in a H shaped pattern
describe the different nuclei for the vagus nerve and their functions
dorsal motor nucleus
- parasympathetic fibres to GIT and lungs
nucleus ambiguus
- motor innervation to the soft palate, larynx and pharynx
- preganglionic nerve fibres to the heart
solitary nucleus
- receives afferents from visceral organs
- taste information
spinal trigeminal nucleus
- afferents that converge here relay sensory information regarding pain, temperature and deep touch of the outer ear, cranial fossa and the mucosa of the larynx
vagus nerve exits the skull via the jugular foramen
summarise the olfactory nerve via information from kenhub
- has no nucleus
- sensory innervation to the nasal mucosa
- fila olfactoria are the branches
- pass through the cribiform plate of the ethmoid bone
- cell bodies are found in the olfactory area covering the superior nasal cavity
- special afferent nerve
summarise the optic nerve via the information from kenhub
- innervates retina of the eye to bring visual information to the brain
- neural fibres originate from photoreceptors of the retina and converge at the optic disc, to form the optic nerve
- optic nerve leaves the orbit via the optic canal
- on the floor of the middle cranial fossa, the nasal parts of each nerve cross to the opposite side to form the optic chiasm and continue as two optic pathways
- cell bodies are found in the retina
describe the oculomotor nerve from the information in kenhub
somatic and visceral efferent motor nerve
- two nuclei - nucleus of the oculomotor nerve (somatic) and the accessory nuclei of the oculomotor nerve (parasympathetic)
- chief motor nerve supplying the eye
- originates from the midbrain
- exits skull through superior orbital fissure
- miosis, lens accommodation
- parasympathetic innervation goes to the sphincter pupillae for miosis
describe the trochlear nerve according to kenhub information
general somatic motor
- originates from the midbrain
- enters orbit through the superior orbital fissure
- superior oblique muscle
describe the trigeminal nerve according to kenhub information
mixed nerve
fibres originate from the brain stem and form the trigeminal ganglion near the apex of the petrous part of the temporal bone
opthalmic division leaves the skull via the superior orbital fissure
maxillary division leaves the skull via the foramen rotundum
mandibular division leaves the skull via the foramen ovale
has four nuclei
motor innervation
- muscles of mastication
- mylohyoid
- anterior belly of digastric
- tensor tympani muscles
sensory
- scalp
- face
- orbit
- anterior two thirds of the tongue
describe the abducens nerve according to information from kenhub
general somatic efferent nerve
lateral rectus muscle
originates from the brainstem and exits the skull via the superior orbital fissure
one nucleus
describe the facial nerve according to information from kenhub
multimodal nerve originating from the brainstem as two separate divisions
the large primary root carries motor fibres
smaller intermediate root carries sensory and parasympathetic fibres
divisions leave the skull via the internal acoustic meatus and travel through the facial canal where they join to form the facial nerve proper and leave the cranium through the stylomastoid foramen
four nuclei
receives taste from the anterior two thirds of the tongue
describe the vestibulocochlear nerve according to information from kenhub
special somatic afferent nerve
vestibular nerve
- balance and motion
cochlear nerve
- hearing
both parts unite to form the vestibulocochlear nerve at the fundus of the internal acoustic meatus, and then enter the cranium through the internal acoustic meatus
describe the glossopharyngeal nerve according to the information from kenhub
originates from the brainstem and exits the skull through the jugular foramen
enables swallowing, salivation, taste sensation
four nuclei
- nucleus ambiguus
- inferior salivatory nucleus
- nuclei of the solitary tract
- spinal nucleus of the trigeminal nerve
motor innervation
- stylopharyngeus
- pharyngeal constrictors
- parotid gland
sensory innervation
- posterior one third of the tongue for both taste and general sensation
- middle ear
- pharynx
- epiglottis
- carotid body and sinus
describe the accessory nerve according to the information from kenhub
exits the skull via the jugular foramen
two nuclei
- ambiguus
- C1-C5
motor innervation
- laryngeal muscles
- sternocleidomastoid
- trapezius
describe the hypoglossal nerve according to information from kenhub
leaves the skull via the hypoglossal foramen
- enables tongue movements
one nucleus
motor
- intrinsic tongue muscles
- extrinsic tongue muscles except for the palatoglossus
