Cranial Nerves VII-XII Flashcards
What is cranial nerve VII?
Facial nerve
Outline the facial nerve
Cranial nerve VII - arises from pons
- muscles of facial expression + stapedius
- special sensory to anterior 2/3 tongue (taste)
- parasympathetic to lacrimal, nasal + salivary glands (except parotid)
How do you test the facial nerve VII?
Test muscles of facial expression
Signs and symptoms of facial nerve VII lesions
- Unilateral facial droop - whole half
- Loss/change in taste to anterior 2/3 of tongue
- Dry eye/mouth
- Hyperacusis - normal sounds are too loud to hear
What is the pathway of the facial nerve?
- from pons into internal acoustic meatus
- into petrous bone + gives off 3 branches (greater petrosal nerve, nerve to stapedius + chorda tympani)
- emerges through base of skull via stylomastoid foramen
- extra cranial branches TZBMC
What does the facial nerve branch into in the petrous bone?
Greater petrosal nerve
Nerve to stapedius
Chorda tympani
Function of the greater petrosal nerve
Parasympathics to lacrimal and nasal glands
What are the functions of chorda tympani (branch of facial nerve)?
- taste to anterior 2/3 tongue
- parasympathics to salivary gland
Causes of facial nerve VII lesions
- lesions in/around internal acoustic meatus
- posterior cranial fossa tumours
- basal skull fracture involving petrous bone
- middle ear disease
- inflammation in facial canal > facial nerve palsy e.g. Bell’s palsy, Ramsay-Hunt syndrome
- parotid disease
What two structures does the facial nerve have a close relation to?
Middle ear cavity
Parotid gland
What is cranial nerve VIII?
Vestibulocochlear nerve
Outline the vestibulocochlear nerve
Cranial nerve VIII - arises from pons
- special sensory to cochlea (hearing)
- vestibular system for balance
What is cranial nerve IX?
Glossopharyngeal nerve
What is cranial nerve X?
Vagus nerve
Pathway of the glossopharyngeal IX + vagus X nerve
- arise from medulla
- run through posterior cranial fossa
- exit through jugular foramen
- enter carotid sheath
- glossopharyngeal IX exits proximally
- vagus X continues inferiorly down neck
Outline the glossopharyngeal nerve
Cranial nerve IX - arises from medulla
- mainly sensory to oropharynx, posterior 1/3 of tongue (sensation + taste) + middle ear cavity
- sensation to carotid sinus + carotid body
- parasympathetic to parotid gland
Outline the vagus nerve
Cranial nerve X - arises from medulla
- muscles of larynx/pharynx + soft palate
- parasympathetic to thoracic + abdominal viscera
- general sensation to lower pharynx + larynx
How do you test the glossopharyngeal nerve IX?
Gag reflex
How do you test the vagus nerve?
Speech
Cough
Soft palate movement
Uvula position
Swallow
Signs and symptoms of vagus nerve lesions
- difficulties with speech
- changes in voice
- dysphagia
- weak cough
- deviated uvula
- nasal regurgitation
What is cranial nerve XI?
Accessory nerve
What is cranial nerve XII?
Hypoglossal nerve
Outline the accessory nerve
Cranial nerve XI - arises from medulla
- motor innervation to trapezius + sternocleidomastoid
How do you test the accessory nerve XI?
Test actions of SCM + trapezius
- SCM: turn head against resistance
- trapezius: shrug shoulders
Signs and symptoms of accessory nerve XI lesions
Winged scapula
Causes of accessory nerve lesions
- injuries, surgery or pathology involving posterior triangle
- posterior cranial fossa tumours
- base of skull fractures
Pathway of accessory nerve XI
- arises from medulla
- through posterior cranial fossa
- entered carotid sheath
- exits + head toward posterior triangle
Outline hypoglossal nerve
Cranial nerve XII - arises from medulla
- innervation to all muscles of tongue (except stylopharngeus)
How do you test the hypoglossal nerve XII?
Tongue movements
Appearance of tongue
Signs and symptoms of hypoglossal nerve XII lesions
Weakness + atrophy of tongue on ipsilateral side
‘Lick your wound’
Pathway of vestibulocohlear nerve VIII
- arises from pons
- passes through internal acoustic meatus
- through petrous bone to inner ear target tissues
How do you test the vestibulocochlear nerve?
Gross hearing tests - whisper/finger rub
Asking about balance
Signs and symptoms of vestibulocochlear nerve VIII lesions
- hearing loss +/- tinnitus
- dizziness (vertigo)
- balance issues
Causes of vestibulocochlear nerve VIII lesions
- vestibular schwannoma (non cancerous inner ear tumour)
- occlusion of labyrinthine artery
- base of skull fracture involving petrous bone
Mnemonic to remember the cranial nerve
Oh Oh Oh To Touch And Feel Virgin Girls Vagina Ah Heaven
- Olfactory
- Optic
- Oculomotor
- Trochlear
- Trigeminal
- Abducens
- Facial
- Vestibulocochlear
- Glossopharyngeal
- Vagus
- Accessory
- Hypoglossal
What is Ramsay Hunt syndrome?
Shingles outbreak which effects facial nerve near the ears (facial nerve)
Herpes zoster
What is the mnemonic to remember where cranial nerves are motor, sensory or both?
Some Say Marry Money But My Brother Says Big Brains Matter More
How does the olfactory nerve pass through the skull?
Cribriform foramina
How does the optic nerve pass through the skull?
Optic canal
How does the Oculomotor nerve pass through the skull?
Superior orbital fissure
+ through cavernous sinus
How does the trochlear nerve pass through the skull?
Superior orbital fissure
+ through cavernous sinus
How does the ophthalmic division of the trigeminal nerve pass through the skull?
Superior orbital fissure
+ cavernous sinus
How does the maxillary division of the trigeminal nerve pass through the skull?
Foramen rotundum
How does the mandibular division of the trigeminal nerve pass through the skull?
Foramen ovale
How does the abducens nerve pass through the skull?
Superior orbital fissure
How does the facial nerve pass through the skull?
Internal acoustic meatus
Then stylomastoid foramen after branching
How does the vestibulocochlear nerve pass through the skull?
Internal acoustic meatus
How does the glossopharyngeal nerve pass through the skull?
Jugular foramen
How does the vagus nerve pass through the skull?
Jugular foramen
How does the accessory nerve pass through the skull?
Jugular foramen
How does the hypoglossal nerve pass through the skull?
Hypoglossal canal
Anterior 2/3rd of the tongue:
- general sensation
- taste
- motor
Anterior 2/3rd of the tongue:
- general sensation: trigeminal
- taste: facial
- motor: hypoglossal
Posterior 1/3rd of tongue:
- general sensation
- taste
- motor
Posterior 1/3rd of tongue:
- general sensation: glossopharyngeal
- taste: glossopharyngeal
- motor: hypoglossal
What is hyperacusis?
Normal sounds are too loud to here
What is the only cranial nerve that comes off the brainstem dorsally?
Trochlear
What are the afferent and efferent limb of gag reflex?
- afferent: glossopharngeal IX
- efferent: vagus X
Differentiate between shingles + Ramsay hunt syndrome
Shingles - red rash on nose + forehead (trigeminal nerve)
Ramsay hunt syndrome - red vesicles on ears (facial nerve)
What causes trigeminal shingles?
Reactivation of varicella zoster virus within trigeminal ganglion
Managment of trigeminal shingles
IV aciclovir
Mnemonic to remember the cranial holes for each cranial nerve
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- Cribiform foramina: I
- Optic canal: II
- Superior orbital fissure: III, IV, Va + VI
- Rotundum: Vb
- Ovale: Vc
- Internal auditory meatus; VII + VIII
- Jugular foramen: XI, X + XI
- Hypoglossal canal: XII
