Cranial Nerves Flashcards
What are the 12 cranial nerves (and their roles)
- Olfactory (smell)
- Optic (vision)
- Occulomotor (all eye movement except LR and SO)
- Trochlear (superior oblique)
- Trigeminal (V1 ophthalmic, V2 maxillary, V3 mandibular)
- Abducens (Later rectus)
- Facial (muscles of face)
- Vestibulocochlear (auditory + balance)
- Glossopharyngeal (sensory and motor of tongue, tonsil pharynx)
- Vagus (motor and sensory of most things below neck)
- Accessory (sterno-mastoid and trapezius)
- Hypoglossal (tongue muscles)
Which cranial nerves have special senses (6)
smell - Olfactory (I)
vision - Optic (II)
Taste - (VII, IX - posterior 1/3, X - anterior 2/3)
Hearing and balance - (VIII)
Which cranial nerves are responsible for “ordinary” sensation
Mainly the trigeminal (V)
The ear from the facial (VII) and glossopharyngeal (IX) nerves
Which cranial nerves control muscle activity
eye muscles - occulomotor (III), trochlear (IV), abducens (VI)
Mastication - trigeminal (V)
Facial expression - facial (VII)
Larynx and pharynx - mainly vagus (X)
Sternomastoid and trapezius - accessory (XI)
Which cranial nerves control autonomic functions (all parasympathetic) for:
Pupillary constriction
Lacrimation
Salivation (submandibular + sublingual glands)
Salivation (parotid gland)
Input to organs in thorax and abdomen
Pupillary constriction - occulomotor (III)
Lacrimation - facial (VII)
Salivation (submandibular + sublingual glands) - facial (VII)
Salivation (parotid gland) - glossopharyngeal (IX)
Input to organs in thorax and abdomen - Vagal (X)
What are the divisions of the trigeminal (V)
Ophthalmic, maxillary, mandibular
What is the parasympathetic pupillary response
Constriction of pupils
What is third nerve palsy
Loss of parasympathetic input to the pupil = fixed, dilated pupil
Pupil is downward and outwards, ptosis
What is the sympathetic pupillary response
Pupillary dilation
(Damage anywhere in sympathetic pathway can lead to a constricted pupil)
What are some causes of a dilated pupil (7)
Youth
Dim lighting
Anxiety/excitement
Mydriatic eye drops (make pupil bigger)
Cocaine overdose
3rd nerve palsy
Brain death
What are some causes of small pupils (5)
Old age
Bright light
Mitotic eye drops (make pupils smaller)
Opiate overdose
Horners syndrome
What are the symptoms of horners syndrome (what often causes it)
Small pupil with ptosis, no sweating in the forehead
Often caused by apical lung tumour
What may cause eye movement disorders (5)
Isolated 3rd nerve palsy
Isolated 4th nerve palsy
Isolated 6th nerve palsy
(Combination of the above)
Supranuclear gave palsy
Nystagmus
What may cause isolated 3rd nerve palsy (what are the symptoms + signs)
Microvascular problems (diabetes or hypertension) - painless, pupil spared
Compressive (raised ICP, artery aneurysm - thunderclap headache) - painful, pupil affected
What may cause 6th nerve palsy (4)
Idiopathic
Diabetes
Meningitis
Raised ICP
What is the most common cause of nystagmus
Toxins (medication and alcohol)
Commonly seen on a Friday night from alcohol
What is trigeminal neuralgia (and what causes it)
Paroxysmal (very sudden) attacks of lancinating pain
Potential Triggers: chewing, speaking, cold air
Caused by a vascular loop - compression of the 5th nerve in the posterior fossa
Who does trigeminal neuralgia affect and what are the treatment options
Affects middle age and older
Treat with carbamazepine
If medication resistant there are surgical options
What is Bell’s Palsy (how does it present)
Idiopathic palsy of the FACIAL (VII) nerve - Lower motor neuron type
Unilateral facial weakness often preceded by pain behind the ear - eye closure affected
what is the treatment for Bell’s palsy
Treated with steroids - usually good recovery
As eye closure is affect eye has to be kept lubricated to prevent corneal damage
What are some causes of upper motor neuron (UMN) and lower motor neuron (LMN) facial paralysis
UMN: e.g. stroke, tumour
LMN: e.g. Bell’s palsy, Lyme, sarcoid
How to differentiate between UMN and LMN facial paralysis
UMN: will NOT involve the forehead
LMN: will involve the forehead
What is vestibular neuronitis (what are the symptoms + cause)
Sudden onset of DISABLING VERTIGO
Vomitting
Gradual recovery
Causes is potentially viral
What is dysarthria
Disordered articulation, slurring of speech
What is dysphagia
Difficulty swallowing
What is dysphonia
Problem with volume of speech
What causes pseudobulbar palsy (what are the symptoms (6))
Bilateral UMN lesions (e.g. vascular lesions in both internal capsules) - often caused by MND
Symptoms:
Dysarthria
Dysphonia
Dysphagia
Spastic, immobile tongue
Brisk jaw jerk
Brisk gag reflex
(Brisk reflexes due to UMN lesion)
What is Bulbar palsy (what are the symptoms)
Bilateral LMN lesions affecting IX - XII e.g. MND, polio, tumours, syphilis, vascular lesions of the medulla
Symptoms:
Wasted, fasciculating tongue
Dysarthria
Dysphonia
Dysphagia
BEWARE OF FEEDING THESE PATIENTS - do swallowing assessment
