Lec 8 - Cranial nerves VII - XII Flashcards
What is cranial nerve VII?
Facial nerve
What is the pathway of the facial nerve (CN VII)?
- Lower puns (junction between pons and medulla)
- This enters the pertrous part of the temporal bone via the internal acoustic meatus.
- There are three branches within the petrous bone.
- Then exits through the base of the skull which is the stylomastoid foramen.
What are the branches within the petrous bone?
- greater petrosal nerve
- chorda tympani nerve
- nerve to stepedius
What is the stylomastoid foramen?
It is the hole between the mastoid process and the styloid process.
what are the special sensory functions of the facial nerve?
- anterior 2/3 of tongue for taste.
what are the autonomic (parasympathetic) functions of the facial nerve?
- lacrimal glands (tears)
- mucosal glands in the nose and roof of mouth
- salivary glands all except the parotid gland.
What are the motor functions of the facial nerve?
for muscles of facial expression.
- fibres from facial nerve to supply muscles of facial expression are outside.
- The stapedious muscle is innervated by motor
- —-> It dampens down excessive vibration at the oral window.
What are the general sensory functions of the facial nerve?
Small area of the external ear.
What are the bits of the facial nerve we see as it comes out the brainstem?
- CN VIII
- CN VII
- Nervus intermedius portion of CNVII
- Geniculate ganglion
What are the nucleus solitaires rostral gustatory portion (special sensory)?
These are nerves carrying special sense taste.
What is the motor nucleus of CN VII (branchial motor)?
These are nerves carrying motor to muscles of facial expression.
What is the superior salivary nucleus (parasympathetic motor)?
These are autonomic fibres to the glands including salivary, lacrimal, mucosal In nose and palate.
What is the pontine trigeminal nucleus (general sensory)?
This is a small area of sensory innervation within the ear.
What are the two roots of the facial nerve at the cerebellopontine angle?
- motor root (larger, just motor axons).
2. Nervus intermedius ( sensory and parasympathetic axons)
How do you clinical test the facial nerve
- by testing the muscles of facial expression and the corneal reflex.
What are some of the symptoms of facial nerve damage?
- hyperacusis
- –> This is sensitivity to loud noises.
- ————> This tells us that there is a problem to the nerve of the stapedius, so can’t act to dampen the vibrations.
- middle ear pathology in the petrous bone can sometimes involve the facial nerve.
What has a close relationship with the vestibulocochlear nerve?
There is a close relationship with vestibulocochlear never within the posterior cranial fossa and both enter internal acoustic meatus.
What do the extra cranial branches of the facial nerve have a close relationship with?
Extracranial branches of facial nerve have close relationship with parotid gland.
What does the corneal reflex do?
- Cotton wool has to reach the cornea
- The ophthalmic division of the trigeminal nerve (sensory) and facial nerve (motor) will detect this.
What controls the afferent limb of the corneal reflex?
The ophthalmic division of the trigeminal nerve
What controls the efferent limb of the corneal reflex?
The facial nerve
What can you not do in facial nerve palsy such as Bell’s palsy?
You won’t be able to close your eye.
What is CN VIII?
Vestibulocochlear
- This is purely sensory.