8. The Trigeminal and Facial Nerves Flashcards
What gives cranial nerves their name?
Emerge through foramina or fissures in the cranium and are covered by tubular sheathes derived from cranial meninges.
What are the roles of the trigeminal nerve CN V?
Sensation for head, motor.
What are the branches of the trigeminal nerve?
CN V1 - opthalmic
CN V2 - maxillary
CN V3 - mandibula
Where does the trigeminal nerve arise from?
The lateral aspect of the pons by a large sensory root and small motor root. Ganglion sits in dural recess (trigeminal cave, lateral to cavernous sinus).
What is the course of the opthalmic nerve (CN V1)?
Exits skull through superior orbital fissure.
What is the role of the opthalmic nerve (CN V1)?
Sensory to: cornea, upper conjunctiva, nasal cavity, frontal sinus, ethmoid sinus, external nose, upper eyelids, forehead and scalp.
How is the opthalmic nerve CN V1 tested?
Corneal reflex.
What are the three branches of the CN V1 opthalmic nerve?
Frontal, nasociliary, lacrimal (-> lacrimal gland, conjunctiva, post ganglionic parasympathetic fibres to lacrimal).
What is the route of the maxillary nerve CN V2?
Exits skull through foramen rotundum.
What is the role of the maxillary nerve CN V2?
Sensory to: conjunctiva, posteroinferior, lateral external nose, maxillary sinus, superior palate, inferior eye lid, upper lip.
How many terminal branches does the maxillary nerve CN V2 have?
14.
What is the route of the mandibular nerve CN V3?
Exits skull through the foramen ovale.
What are the roles of the mandibular nerve CN V3?
Sensory to: mucous membranes, lower lip, chin, external ear, anterior two thirds of tongue.
Motor to: masseter, temporalis, medial and lateral pterygoids, mylohyoid, digastric, tensor tympani, tensor vele palatini.
What parasympathetic ganglia are associated with mandibular nerve CN V3?
Submandibular ganglion - submandibular salivary gland, sublingual salivary gland.
Otic ganglino - parotid salivary gland.
Where does the facial nerve CN VII exit the skull?
Through the stylomastoid foramen.
What are the functions of the facial nerve CN VII?
Motor to: muscles of facial expression, digastric, stylohyoid, stapedius.
Sensory to: general to small area of skin close to external acoustic meatus; special sensory taste to corda tympani from lingual nerve to anterior 2/3 of tongue.
Parasympathetic: pterygopalatine parasympathetic ganglion -> lacrimal gland, submandibular gland, sublingual gland.
What is the course of the facial nerve?
Motor cortex -> pons -> internal acoustic meatus within petrous temporal bone -> facial canal within temporal bone, gives rise to great petrosal nerve, nerve to stapedius, chorsa tympani nerve -> stylomastoid foramen to exit temproal bone and give rise to posterior auricular branch -> branches to face and neck through parotid gland.
What are the branches of the facial nerve?
Ten sulus buggered my cat.
Temporal, zygomatic, buccal, narginal mandibular, cervical.
What does the temporal nerve innervate?
Occipitofrontalis and orbicularis oculi (superior).
What does the zygomatic nerve innervate?
Orbicularis oculi (inferior).
What does the buccal nerve innervate?
Orbicularis oris, buccinator, zygomaticus.
What does the marginal mandicular nerve innervate?
Mentalis.
What does the cervical nerve innervate?
Platysma.
How is the facial nerve examined?
Observation for symmetry, ask about changes, examination of facial muscles.
How are the facial muscle examined?
Occipitofrontalis - raise eyebrows against resistance.
Orbicularis oculi - scrunch up eyes against resistance.
Buccinator - puff out cheeks against resistance.
Levator labii superioris.
Depressor labii inferioris - show teeth against resistance.
What are non-traumatic causes of facial nerve palsy?
Inflammation, infection (viral Herpes, parotitis from S. aureus), compression by parotid tumour.
What are traumatic causes of facial nerve palsy?
Fractures of temporal bone, stabbing, gunshots, childbirth.
What are iatrogenic causes of facial nerve palsy?
Surgery - parotidectomy.
How is Bell’s palsy distinguished from stroke?
Bell’s - all muscles of facial expression paralysed.
Stroke - frontal sparing, occipitofrontalis and orbicularis oculi not paralysed due to bilateral innervation.
