Anatomy of Cranial Nerve Testing Flashcards
CN V1
SENSORY
CN V2
SENSORY
CN V3
SENSORY + MOTOR
Where is the intracranial part of the CNS between?
Between the point of connection of the CNS and their respective base of skull foraminae
What are the 3 divisions of the trigeminal nerve? What fibres do they contain?
CN V1 - ophthalmic - sensory
CN V2 - maxillary - sensory
CN V3 - mandibular - sensory and motor
What is the only cranial nerve to attach to the pons?
CN V
Where does CN V attach in the intra-cranial cavity?
Pons
Describe the attachment of CN V to the pons?
Laterally
Half way between the midbrain and medulla
Name the only nerve in the anterior cranial fossa.
CN I (olfactory)
What is the function of the olfactory nerve?
Sensory - smell
Describe the extra cranial part of CN I.
Sensory so on body wall
Lays within olfactory mucosa of nasal cavity
What is the location of the cranial fossa of CN I?
Cribiform plate of ethmoid bone
Anterior cranial fossa
What is the intracranial part of CN I (i.e CNS connection)?
Olfactory nerves synapse in the olfactory bulb
Then pass through the olfactory tract
What is the function of the optic nerve (CN II)?
Sensory - vision
Describe the extra-cranial part of CN II.
Neurons of the retina travel posteriorly via the optic nerve from the posterior hemisphere of the eye through the orbit
What is the location of the cranial fossa of CN II?
Optic nerve possess through optic canal
Middle cranial fossa
What is the intracranial part of CN II?
Travels around pituitary stalk to optic chiasm to form the optic tract
Where is the connection of CN II to the CNS?
Diencephalon
How is CN I tested?
Note: not done routinely
Ask the patient to smell a familiar smell e.g lemon while covering the contralateral nostril
List the 5 ways that CN II can be tested.
- Acuity
- Colour
- Fields
- Reflexes
- Fundoscopy
What is the function of CN III?
Sensory and Motor
Eye movement - motor
Pupil constriction - parasympathetic
Where does CN III connect with the CNS?
Midbrain
What is the intracranial part of CN III?
Travels towards the orbit in the lateral walls of the cavernous sinus
What is the location of the cranial foraminae of CN III?
Superior orbital fissure
Describe the extra-cranial part of CN III?
Passes through SOF into orbit to supply extraoccular muscles
Where do parasympathetics of CN III synapse? What is their function?
Ciliary ganglion
Pupillary constriction
How is CN III tested?
Shine a light into the patient’ eyes to check for pupillary constriction
Where does CN IV connect to the CNS?
Midbrain
Describe the intracranial part of CN IV?
Travels towards the orbit in the lateral wall of the cavernous sinus
Where is the location of the cranial foraminae of CN IV?
Superior orbital fissure
Describe the extra-cranial course of CN IV?
Travels through SOF into orbit to supply only 1 muscle
What muscle is supplied by CN IV?
Superior oblique
At what junction does CN VI connect with the CNS?
Pontomedullary junction
Describe the intracranial course of CN VI?
Travels towards the orbit within the cavernous sinus
Where is the cranial foraminae of CN VI located?
Superior orbital fissure
Describe the extra cranial course of CN VI.
Passes through SOF into orbit to supply only the LATERAL RECTUS muscle
What artery runs close to CN VI?
Internal carotid artery
How is CN VIII tested?
Rinnie and webber
Describe the extra cranial course of CN VIII.
Axons from vestibular and cochlear apparatus
Where is the cranial foramina of CN VIII located?
Posterior cranial fossa
Internal acoustic meatus
think ‘acoustic is sound’
At what junction does CN VIII connect to the CNS?
Pontomedullary junction
Describe the intracranial course of CN VIII.
Travels posteromedially from the internal acoustic meatus to the pontomedullary junction
What is the function of CN VIII?
SENSORY
Hearing and balance