Cranial Nerves And Epilepsy Flashcards
What is cranial nerve I and what does it do?
Olfactory nerve
It provides special visceral afferent fibres for smell
Connects to the brain
Passes through the cribiform plate of the skill
Disorder- altered/loss of sense of smell
What is cranial nerve II and what does it do?
Optic nerve
It provides special somatic afferent fibres for vision
It connects to the brain
Passes through the optic canal of the skull
Deficit- optic field defects
What is cranial nerve III and what does it do?
Occulomotor nerve
Innervation extrinsic eye muscles that enable most movements of the eye, that raise the eyelid and constrict the pupil
Connects to the midbrain
Passes through the superior orbital fissure of the skull
Deficit- ptosis (inactivation of the levator palpebrae), mydriasis (decreased tone of the constrictor pupillae muscle), down and out (unopposed left superior oblique and lateral rectus muscle)
What is cranial nerve IV and what does it do?
Trochlear nerve
Provides general somatic efferent to the extraocular superior oblique muscle
It assists in depressing and abducting the eye
Connects to the midbrain
Passes through the superior orbital fissure of the skull
What is cranial nerve V and what does it do?
Emerges from the pons
Has 3 divisions (ophthalmic, mandibular and. Maxillary)
Largest of the cranial nerves
Mixed nerve- motor and sensory
What does the ophthalmic branch of the trigeminal nerve do?
Exits the brain through the superior orbital fissure
Sensory nerve that innervation the cornea, skin of the forehead scalp, eyelids and nose and the mucous membranes of paranasal sinuses and nasal cavity
What does the maxillary branch of the trigeminal nerve do?
Exits the brain through the foramen rotundum
Sensory nerve that innervation- skin of face over maxilla, upper teeth, mucous membrane of nose, maxillary sinus and palate
What does the mandibular branch of the trigeminal nerve do?
Mixed nerve
Leaves the brain through the foramen ovals
Motor function that innervates the muscles of mastication, mylohyoid, aneroid belly of digastric, tensor veil palatine, tensor tympani
Sensory function that innervates the skin of the cheek, the skin over the mandible and side of the head, teeth of lower jaw and TMJ, mucous membrane of lower jaw, anterior 2/3 of tongue
What is sensory trigeminal neuropathy?
Progressive, painless loss of trigeminal sensation
Normally unilateral
May affect one or al trigeminal divisions
No motor weakness
What is numb chin syndrome?
Sensory neuropathy presenting with numbness in the chin in the distribution of the mental nerve and its branches of the mandibular division of the trigeminal nerve
A numb chin is an important diagnostic symptom of metastatic disease
Odontogenic- dental abscess, dental anaesthesia, dental trauma, osteomyelitis and benign tumours
Systemic- amyloidosis, sickle cell disease, sarcoidosis, multiple sclerosis, HIV, diabetes mellitus
Local tumour or metastasis
What is trigeminal neuralgia?
Episodic neuropathic pain
Sudden, usually unilateral, severe, brief stabbing, recurrent episodes of pain in the distribution of one or more branches of the trigeminal nerve
What is cranial nerve VI and what does it do?
Abducens nerve
Provides general somatic efferent fibres for eye abduction
Innervates the lateral rectus muscles
Passes through the superior orbital fissure of the skull
What is cranial nerve VII and what does it do?
Facial nerve
Mixed motor and sensory
Motor- muscles of facial expression, stapedius muscle, posterior belly of digastric and stylohyoid muscles
Sensory- taste to anterior 2/3 of tongue
Parasympathetic- supplies many of the glands of the head and neck
What are the 5 branches of the facial nerve?
Frontal (temporal) Zygomatic Buccal Mandibular Cervical
What is Bell’s palsy?
Unexplained episode of facial muscle weakness or paralysis
