5. Cranial Nerves VII-XII Flashcards
What is CNVII?
Facial (motor, special sensory taste, parasympathetic)
Where does the facial nerve originate?
Pons
What are the target tissues of CNVII?
Muscles of facial expression
Taste from anterior 2/3 of tongue
Glands - lacrimal, salivary, mucosal (nose)
What are the signs and symptoms of damage to facial nerve supplying muscles of facial expression?
Unilateral facial droop
What can damage the CNVII?
- Lesions in/around internal acoustic meatus and posterior cranial fossa
- Basal skull fracture (involving petrous bone)
- Middle ear disease
- Inflammation in facial canal - facial nerve palsy
- Parotid disease
What is the difference in presentation between Bell’s palsy and Ramsay-Hunt syndrome?
Both have facial weakness
Ramsay-Hunt has rash/vesicles on ear as well
What is the route of the facial nerve?
Passes through internal acoustic meatus
Runs into petrous bone and gives off 3 branches
Then runs through facial canal
Then merges through base of skill via stylomastoid foramen
Then gives of muscles of facial expression
What does the greater petrosal nerve supply?
Lacrimal gland
Nasal
Oral/palatal mucosal glands
(Parasympathetic)
Where does the greater petrosal nerve branch off the facial nerve?
At the geniculate ganglion
What is the second branch off the facial nerve?
Nerve to stapedius
What is the third branch of the facial nerve?
(Sensory)
Chorda tympani
How can you tell the difference in appearance between a stroke and Bell’s palsy?
Can raise eyebrows with stroke due to dual cortical input to upper part of face
What is CNVIII?
Vestibulocochlear (special sensory)
Where does CNVIII originate?
Pons
How do you test CNVIII?
Gross bedside hearing tests (whisper/finger rub) and tuning fork test
What do patients with damage to CNVIII present with?
Hearing loss
Dizziness (vertigo)
Tinnitus
What can affect the CNVIII?
Vestibular schwannoma (and other posterior cranial fossa tumours)
Occlusion of labyrinthine artery
Base of skull fracture (involving petrous bone)
Brainstem lesions
What are the symptoms and signs of vestibular schwannoma?
Unilateral hearing loss
Tinnitus
Vertigo
Numbness, pain or weakness down one half of face
What is the pathway of CNIX and CNX?
Medulla
Run through posterior cranial fossa
Exit through jugular foramen
Enter into carotid sheath
What is CNIX?
Glossopharyngeal nerve
What is CNX?
Vagus nerve
What are the target tissues of the glossopharyngeal nerve?
Mainly sensory (oropharynx/tonsils) Posterior 1/3 tongue 1 swallowing muscle Parasympathetic to parotid gland Afferent from carotid sinus and body
What are the target tissues of the vagus nerve?
Motor and sensory
Muscles of larynx/pharynx - including soft palate
Sensory (larynx/laryngopharynx)
Parasympathetic to many tissues
What may patients present with if they have pathology with glossopharyngeal or vagus nerve?
Difficult with swallowing
Weak cough
Difficulties with speech or changes in voice
How can you test the CNIX and CNX?
Speech, swallow, cough
Soft palate movement and uvula position (CNX)
Gag reflex (IX and X)
What can cause damage to CNIX and CNX?
Recurrent laryngeal nerve branch of CNX
Pathology involving carotid sheath structures
Posterior cranial fossa tumours
Brainstem lesions
What is CNXI?
Accessory nerve
What is CNXII?
Hypoglossal nerve (motor)
What are the pathways of the CNXI and CNXII?
Arise from medulla
Run through posterior cranial fossa
Enter into aortic sheath
Hypoglossal exits and travels towards tongue
Accessory exits and heads towards posterior triangle
What is hypoglossal nerve responsible for?
Tongue movements and protrusion
What can affect the hypoglossal nerve?
Surgery/pathology in proximity to or involving upper carotid sheath, internal and external carotid artery
Posterior cranial fossa tumours
Brainstem lesions involving hypoglossal nucleus
What muscle protrudes tongue?
Genioglossus
What s the gemioglossus innervated by?
CNXII
What are the target tissues of CNXI?
SCM
Trapezius
What can damage the accessory nerve?
Injuries, surgery or pathology involving posterior triangle
Posterior cranial fossa tumours
Base of skull lesions
Brainstem lesions
Where does accessory nerve emerge?
Deep to posterior border of SCM to enter posterior triangle
Runs superficially in posterior triangle to reach trapezius
