Cranial nerves 7-12 Flashcards
What is CNVII?
facial nerve
Where does CNVII originate?
lower pons
What is the route of CNVII?
power pons –> petrous bone via internal acoustic meatus –> 3 branches within the petrous bone –> exits through stylomastoid foramen
What does CN VII supply?
muscles of facial expression
- stapedius muscles
- digastirc muscles and stylohyoid
- lacrimal glands (tears)
- mucosal glands in nose and roof of mouth
- salivary glands - NOT PAROTID
- anterior 2/3 of tongue (TASTE)
- sensory to small area of external ear
What is the function of stapedius?
dampens down vibration of stapes
What fibres does CNVII carry?
SVE
GVE
SVA
GSA
What is the function of the facial nerve?
- Special sensory
- parasympathetic
- motor
- general sensory
What functions are special sensory?
taste to anterior 2/3 of tongue
What functions are autonomic?
-glands
What functions are motor?
muscles of facial expression and stapedius
What function are general sensory?
small area of external ear
What nerve gives the ability of the tongue to feel temperature and pain (general sensory)?
trigeminal nerve mandibular division CN Vc
Where are the cell bodies of sensory neurones found?
in the geniculate ganglion outside of the brainstem in the petrous bone
What branch of the facial nerve arise in the petrous bone?
- greater petrosal nerve
- chorda tympani
- nerve to stapedius
then passes through sytlomastoid foramen and gives the 5 branches TZBMC
What does the greater petrosal nerve carry?
parasympathetics to lacrimal glands, nasal glands and glands of the palate
What does the chordates tympani nerve carry?
- carries special sensory taste to the anterior 2/3 of the tongue
- autonomcs to the salivary galnds
What does the nerve to stapedius carry?
nerve innervation to the stapedius to dampen down the vibrations the stapes bone gets
How do you test the facial nerve?
- muscles of facial expression
- corneal reflex
- can present with variety of signs and symptoms depending on where along the nerve route the pathology lies
- need to ask for presence and absence of certain things (taste, dry eyes, hyperacusis)
What pathologies can involve the facial nerve?
-middle ear pathology
What are the 2 limbs of the corneal reflex?
afferent - Va
efferent - facial nerve - supplies obicularis oculi
What is bells palsy?
compression or damage to the facial nerve causing paralysis of the facial muscles on one side of the face
What could happen if the parotid gland became swollen?
compress the extrocranial branches of the facial nerve
What is CNVIII?
vestibulocochlear
Where does CNVIII originate?
pons
What is the route of CNVIII?
takes signals from cochlea and vestibular system and becomes the vestibulocohlear nerve –>internal acoustic meatus –> lower pons
What is the function fo CN VIII?
special sensory - hearing and balance
What fibres does CNVIII carry?
SSA
What does CNVIII supply?
semicircular canals, cochlear
How could you test CNVIII?
- crude hearing test
- enquire about balance
What could cause hearing loss? (sensorineural)
-damage involving cochlea, cochleae component of vestibulocochlear nerve
What is presbyacusis?
old-age related hearing loss
What could cause vertigo?
pathology involving semicircular canals
What is an acoustic neurone?
benign tumour involving CNVIII
-tumours of the Schwann cells - their presence causes compression of the whole nerve (an potentially nerves near by - facial nerve and trigeminal nerve)
What are the symptoms with acoustic neuromas?
- unilateral hearing loss
- tinnitus
- vertigo
- numbness, pain or weakness down one half of the face
What is CN IX?
the glossopharyngeal nerve
What is the origin of CN IX?
medulla
What is the route of CN IX?
travels from medulla –> jugular foramen –> through carotid sheath –> leaves quite high up
What are the fibres that are carried by CN IX?
SVE
GVA
GSA
GVE
What are the functions of CN IX?
General sensation, special sensory, autonomic, motor
What is the motor function of CN IX?
-SVE fibres carry innervation to the stylopharynges muscle - assists in swallowin
What is the special sensory function of CN IX?
taste and general sensation to the posterior 1/3 of the tongue
What is the general sensation function of CN IX?
- palatine tonsils and oropharynx
- middle ear and tympanic membrane
- sensory to carotid sinus and body (BP, pO2, PCO2)
What is the autonomic function of the CN IX?
innervation to the parotid gland
How do you test the CN IX?
- isolated regions are rare
- tested in conjunction with vagus nerve (ask patients to swallow)
- sensory limb of gag reflex
When would you test the gag reflex?
only if concerns around swallowing and integrity of the nerves involved in this reflex
What is CNX?
the vagus nerve
Where does CNX originate?
medulla
What is the route of CNX?
Medulla –> jugular foramen –> carotid sheath –> through neck into thorax and abdomen
What is the function of CNX?
- general sensory
- motor
- autonomic
What does CNX supply?
- sensory to lower pharynx and larynx
- sensory to small part of external ear and tympanic membrance
- muscles of the soft palate, pharynx and larynx
- autonomic to thoracic (heart) and abdominal viscera
What does the left and right recurrent laryngeal nerves turn under?
left - arch of aorta
right - right subclavian
How do you test for CNX ?
- listen to speech, cough, ability to swallow
- movement of uvula and soft palate when saying aah
- efferent limb of the gag reflex
What could injuries to its branches cause and when would it happen?
hoarseness and dysphonia
-injury to recurrent laryngeal nerve during thyroid surgery
What nerve fibres does CNX carry?
GVE GVA SVE SVA GSA
What is CN XI?
Spinal accessory nerve
What is the function of CNXI?
motor
What muscles does CNXI supply?
trapezius and SCM
What is the origin and route of CNXI?
medulla –> jugular foramen –>carotid sheath –> exits to pass deep to SCM –>across posterior triangle to enter trapezius
How is CN XI formed?
rootlets from the cervical spine and brain stem collect to form CN XI
How do you test CN XI?
- shrug shoulders against resistance
- turn head against resistancy
When is CN XI vulnerable?
-lymph node biopsies, surgery and stab wounds (quite superficial in the posterior traingle)
What nerve fibres run in CNXI?
GSE
SVE
What is CN XII?
hypoglossal nerve
Where does CN XII originate?
medulla
What is the route of CN XII?
medulla –> hypoglossal canal –> runs medial to the angle of the mandible and crosses internal and external carotid arteries in the neck
What is the function of CNXII?
motor
What does CNXII supply?
muscles of the tongue (except one)
-change shape of tongue, protract, retract, elevate
How do you test CNXII?
-inspection and movement of tongue
What could pathology relating to CNXII include?
-weakness and atrophy of the tongue muscles on ipsilateral side
