Cranial Nerves Flashcards
What are all the special sensory cranial nerves?
CNI, CNII, CNVII, CNVIII, CNIX
What modalities does CNI contain?
Special sensory
What modalities does CNII contain?
Special sensory
What modalities does CNIII contain?
Motor and parasympathetics
What modalities does CNIV contain?
Motor
What modalities does CNV contain?
Sensory in all branches, motor in CNV3
What modalities does CNVI contain?
Motor
What modalities does CNVII contain?
Motor, special sensory and parasympathetics
What modalities does CNVIII contain?
Special sensory
What modalities does CNIX contain?
Sensory, special sensory, motor and parasympathetics
What modalities does CNX contain?
Sensory, motor, parasympathetics
What modalities does CNXII contain?
Motor
Which of the cranial nerves connect with the CNS at the midbrain?
Oculomotor and trochlear
Which of the cranial nerves connect with the CNS at the pons?
Trigeminal
Which of the cranial nerves connect with the CNS at the ponto-medullary junction?
Abducens, facial and vestibulocochlear
Which of the cranial nerves connect with the CNS at the spinal cord?
Spinal accessory
What defines the ‘intracranial’ part of a cranial nerve course?
Between their point of connection with the CNS and their base of skull foramina
What cranial cavity does CNI pass through? In which cranial fossa is this?
Cribriform plate of the ethmoid bone - anterior cranial fossa
Where do the olfactory nerves synapse? They then travel through where to reach their cortical areas?
Olfactory bulb / olfactory tract
Intracranially, CNII travels around the pituitary stalk to what structure? It then forms what structure?
The optic chiasm / the optic tract
Where does the optic nerve connect with the CNS?
At the diencephalon
How would you test the olfactory nerve?
Ask the patient to smell a familiar smell while covering the other nostril
How would you test the optic nerve?
Visual acuity, colour vision, visual fields, fundoscopy, pupillary light reflexes
What is the parasympathetic function of CNIII? What muscle is this via?
Pupillary constriction via sphincter pupillae
Which base of skull foramina does the oculomotor nerve pass through?
Superior orbital fissure
How can you test the parasympathetic function of CNIII?
Pupillary light reflexes for pupillary constriction
What is the motor function of the trochlear nerve?
Eye movement - superior oblique muscle
Which cranial nerves travel along the lateral wall of the cavernous sinus?
Oculomotor and trochlear nerves
Which cranial nerve travels within the cavernous sinus?
Abducens nerve
What is the motor function of the abducens nerve?
Eye movement via the lateral rectus muscle
How would the oculomotor, trochlear and abducens nerve all be tested for?
The H test to assess eye movements
The vestibulocochlear nerve is responsible for what?
Hearing and balance
Which base of skull foramina does the vestibulocochlear nerve pass through? Which cranial fossa is this in?
Internal acoustic meatus - posterior cranial fossa
How is the vestibulocohlear nerve tested for?
Rhinne and Weber’s tests
The spinal accessory nerve ascends through which base of skull foramina? And then travels towards which base of skull foramina?
Foramen magnum / jugular foramen
How is the spinal accessory nerve tested?
Ask patients to shrug their shoulders and turn their head against resistance
What is the motor function of the hypoglossal nerve?
Motor function to the muscles of the tongue
Where does the hypoglossal nerve connect with the CNS in relation to the pyramids of the medulla?
Laterally
Describe the extracranial part of the hypoglossal nerve?
Descends lateral to the carotid sheath and then turns anteriorly at the level of the hyoid bone towards the lateral aspect of the tongue
The hypoglossal nerve innervates all muscles ending in glossus except which one?
Palatoglossus
If there is unilateral hypoglossal nerve pathology, what direction will the tongue face when asked to stick it out straight?
Towards the side of the injured nerve
Which base of skull foramina does CNV1 pass through?
Superior orbital fissure
Which base of skull foramina does CNV3 pass through?
Foramen ovale
What is the motor function of CNV3?
The muscles of mastication, tensor veli palatini and tensor tympani
What is the one pair of jaw opening muscles supplied by the trigeminal nerve?
Lateral pterygoid
Which aspect of the trigeminal nerve is responsible for the afferent part of the corneal reflex?
CNV1
Which base of skull foramina does the facial nerve pass a) IN b) OUT?
a) Internal acoustic meatus b) stylomastoid foramen
What is the motor function of the facial nerve?
Muscles of facial expression
The chorda tympani is a branch of which cranial nerve?
Facial nerve
What is the function of the chorda tympani?
Taste supply to the anterior 2/3rds of the tongue AND parasympathetics to the submandibular and sublingual glands
What supplies the stapedius muscle in the inner ear?
Facial nerve
What is the function of the tensor tympani muscle?
Reduces the noise produced by chewing
What two nerves combine to form the lingual nerve?
Chorda tympani branch of the facial nerve and CNV3
How can the motor function of CNVII be tested?
Ask patient to close eyes tightly, raise eyebrows, smile, puff out cheeks, whistle
What nerve supplies taste sensation to a) the anterior 2/3rds of tongue? b) the posterior 1/3rd of tongue?
a) Facial nerve b) Glossopharyngeal nerve
Which base of skull foramina does the glossopharyngeal nerve pass through?
Jugular foramen
From which structures does the glossopharyngeal nerve ascend towards the jugular foramen?
The pharyngeal mucosa, carotid body and sinus, posterior 1/3rd of tongue
Which cranial nerve is responsible for taste sensation to the vallate papillae of the posterior 1/3rd of the tongue?
Glossopharyngeal
What is the only motor function of the glossopharyngeal nerve?
Stylopharyngeus muscle
Where does the glossopharyngeal nerve send visceral afferents to?
The carotid sinus baroreceptors and carotid body chemoreceptors
Which cranial nerve is responsible for referred pain between the pharynx and the ear?
Glossopharyngeal
The axons of the vagus nerve supply lots of structures between where?
The palate and the midgut
The vagus nerve runs inferiorly to the thorax and then does what?
Gives off the recurrent laryngeal nerve to turn back superiorly to the muscles of the larynx
The right recurrent laryngeal nerve curves under where?
The right subclavian artery
The vagus nerve passes through the diaphragm with what structure? At what spinal level?
Oesophagus - T10
The vagus nerves very last parasympathetic axons pass to where?
The splenic flexure of the colon
What nerve forms the efferent limb of the gag reflex?
Vagus nerve
When testing the vagus nerve you should ask the patient to say ahh - what will happen to the uvula if there is unilateral vagus nerve pathology?
The uvula will move away from the affected side
Apart from saying ahh and observing the uvula, what are some other ways of testing the vagus nerve?
Ask patient to swallow, and listen to their speech for hoarseness
What modalities does CNXI contain?
Motor
Which of the cranial nerves connect with the CNS at the medulla?
Glossopharyngeal, vagus and hypoglossal
Which base of skull foramina does CNII pass through? In which cranial fossa is this?
Optic canal in the middle cranial fossa
What is the motor function of the oculomotor nerve?
Eye movements (superior and inferior rectus, medial rectus, inferior oblique) and levator palpebrae superioris
Where do the parasympathetics of the oculomotor nerve synapse?
The ciliary ganglion
What base of skull foramina does the trochlear nerve pass through?
Superior orbital fissure
What base of skull foramina does the abducens nerve pass through?
Superior orbital fissure
What muscles are supplied by the spinal accessory nerve?
Trapezius and sternocleidomastoid
Which base of skull foramina does the hypoglossal nerve pass through?
Hypoglossal canal
What nerve innervates the palatoglossus muscle?
Vagus nerve
Which base of skull foramina does CNV2 pass through?
Foramen rotundum
What are the 3 pairs of jaw closing muscles supplied by CNV3?
Masseter, temporalis and medial pterygoids
The facial nerve spends most of its time within what bone of the skull?
Temporal bone
What are the muscles of facial expression which are supplied by the facial nerve?
Orbicularis oculi, orbicularis oris, frontalis and elevators of lips
From the jugular foramen, the glossopharyngeal nerve sends motor/parasympathetic axons to where?
The stylopharyngeus muscle and the parotid gland
What is the parasympathetic function of the glossopharyngeal nerve?
Parotid gland (secretory)
Which cranial nerve is responsible for forming the afferent limb of the gag reflex?
Glossopharyngeal
What base of skull foramina does the vagus nerve run through?
The jugular foramen
Which cranial nerve runs within the carotid sheath?
Vagus
The left recurrent laryngeal nerve curves under where?
The arch of the aorta
The majority of cranial nerves exit their base of skull foramina anteriorly - what are the exceptions to this?
Trochlear exits posteriorly and vestibulocochlear exits laterally
The soma of sensory nerve cells within cranial nerves will be found where?
In ganglia outside the CNS
Nuclei for the motor cranial nerves are found near where?
The midline of the brainstem
Which cranial nerve nuclei are in the midbrain?
Oculomotor and trochlear
Which cranial nerve nuclei are in the pons?
Trigeminal and abducens
Which cranial nerve nuclei are in the medulla?
Glossopharyngeal nerve, vagus nerve, spinal accessory nerve, hypoglossal nerve
Which cranial nerve nuclei is located on the border of the pons and medulla?
Facial nerve
What is the solitary nucleus responsible for?
Taste and visceral sensory information
What are the superior and inferior salivatory nuclei responsible for?
Parasympathetics to salivary glands
What is the nucleus ambiguus responsible for?
Motor supply to the muscles of the pharynx, larynx and upper oesophagus
What spinal cord tract is responsible for the motor input to cranial nerves?
Corticobulbar tract