5.2 CN VIII-XII Flashcards
What fibres does CN VIII carry?
Special sensory
What are the functions of CN VIII?
Hearing
Balance
What is the route of CN VIII?
Pons -> Internal auditory meatus -> Petrous bone -> Brain stem -> Primary auditory cortex in temporal bone
How can you test CN VIII?
Hearing
Balance
What is an acoustic neuroma?
Benign tumours of the Schwann cells surrounding the vestibular component of vestibulocochlear nerve (CN VIII)
What type of hearing loss does damage involving vestibulocochlear nerve, its brainstem nucleus or cochlea cause?
Sensorineural
What is presbyacusis?
Old-age related hearing loss
Both ears
(Bilateral sensorineural hearing loss)
What can cause disturbance of balance (vertigo) and nystagmus?
Pathology involving semi-circular canals, vestibulocochlear nerve and brain nucleus
What does presence of acoustic neuroma cause?
Compression of the whole nerve and CNs in close proximity
What symptoms may you get in acoustic neuromas?
Vestibulocochlear
- Unilateral hearing los
- Tinnitus
- Vertigo
Facial
- Numbness
Trigeminal
- Pain or weakness down one side of face
Which CNs arise from he medulla?
Glossopharyngeal IX
Vagus X
Accessory XI
Hypoglossal XII
What types of nerve does CN IX carry?
GS
SS
A
M
What are the functions of general sensation of CN IX?
GS of soft palate, tonsils and pharynx (oropharynx)
Sensory from carotid body and sinus
- Senses pressure -> carotid sinus massage
Taste and general sensation posterior 1/3 tongue
What are the special sensory functions of CN IX? What is the clinical relevance?
Middle ear and tympanic membrane
Explains why an upper respiratory tract infection gives referred pain to the ear
(Pain in throat is glossopharyngeal)
What is the autonomic input of CN IX to?
Parotid gland
What is the motor innervation of CN IX to?
Stylopharyngeus
Helps with swallowing
Which nerve is CN X?
Vagus
Describe the route of vagus nerve
Medulla -> jugular foramen -> neck -> carotid sheath
Which foramen does the vagus nerve exit from?
Jugular foramen
What are the functions of the vagus nerve?
Sensory to lower pharynx and larynx
Motor to muscles of soft palate, pharynx and larynx
Parasympathetic to thoracic and abdominal viscera
What structure dos the right recurrent laryngeal nerve turn under?
Right subclavian
What structure does the left recurrent laryngeal nerve turn under?
Arch of aorta
How can you test CN X?
Note speech
Swallow and couch
Say ahh observing uvula
Gag reflex - efferent limb
What can cause hoarseness and dysphonia?
Injury to recurrent laryngeal branch of vagus nerve
