Disorders of Cranial Nerves Flashcards
Run through the cranial nerves quick to get the ball rolling `
1 - Olfactory 2 - Optic 3 - Occulomotor 4 - Trochlear 5 - Trigeminal (opthalmic, maxillary, mandibular) 6 - Abducens 7 - Facial 8 - Vestibulocochlear 9 - Glossopharyngeal 10 - Vagus 11 - Accessory 12 - Hypoglossal
Which of the cranial nerves carry special senses? What are their senses?
- 1: olfaction
- 2: vision
- 7, 9, 10: Taste (vagus at root of tongue and epiglottis)
- 8: hearing and balance
Which cranial nerves carry ordinary somatosensory fibres?
- Mainly branches of 5
- The ear from: 7 & 9
Are the autonomic functions of the cranial nerves sympathetic or parasympathetic
Parasympathetic bilo
Which cranial nerves control muscle activity? (& the muscles they control)
- 3, 4, & 6: eye muscles (LR6SO4 - rest 3)
- 5: Muscles of mastication
- 7: Muscles of facial expression
- 9: stylopharyngeus & sup. pharyngeal constrictor
- 10: Muscles of larynx and pharynx
- 11: SCM and traps
- 12: tongue
Which cranial nerves have autonomic functions? What are these functions?
- 3: Pupillary constriction
- 7: Lacrimation
- 7: Salivation (@ submandibular and sublingual)
- 9: Salivation (@ Parotid)
- 10: Input to organs in thorax and abdomen
What does clinical examination of the first four cranial nerves test?
- CN I: smell (unilateral / bilateral loss)
- CN II: visual acuity, visual fields, pupillary reactions, fundoscopy, colour vision
- CN III: ptosis, pupil size, pupillary reactions, eye moevments
- CN IV: eye movement
What does clinical examination of the second four cranial nerves test?
- CN V: sensation of the face, muscles of mastication, jaw jerk, corneal reflex (?)
- CN VI: eye movement
- CN VII: facial expression, corneal reflex, taste
- CN VIII: hearing and balance
What does clinical examination of the last four cranial nerves test?
- CN IX & X: palate movement, gag reflex, speech quality, quality of cough
- CN XI: head turning and shoulder shrugging
- CN XII: Appearance, movement and power of tongue
Which cranial nerves are involved in the pupillary light reaction?
- CN II: afferent
- CN III: efferent
Which cranial nerves are involved in the corneal reflex?
- CN V: afferent
- CN VII: efferent
Which cranial nerves are involved in the gag reflex?
- CN IX: afferent
- CN X: efferent
Where are the cranial nerve nucleii of III & IV located?
In the mid brain
Where are the cranial nerve nucleii of VI, VII & VIII located?
Pontomedullary junction
Where is the cranial nerve nuclei of VIII located?
Pontomedullary junction
Where are the cranial nerve nucleii of IX, X, XI & XII located?
In the medulla
Where might issues with cranial nerves III, IV & VI indicate there is a problem?
Superior orbital fissure
What is optic neuritis? Signs?
- Demyelination within the optic nerve
- Monocular visual loss
- Pain on eye movement
- Reduced visual acuity
- Reduced colour vision
(often associated with MS)
What effect does CN III palsy have on pupillary response?
- Responsible for parasympathetic input (constriction), therefore loss of input causes a fixed, dilated pupil
- A constricted pupil could indicate damage to the sympathetic pathway (not CN’s)
Causes of dilated pupils?
- Youth
- Darkness
- Anxiety / excitement
- Mydriatic eye drops
- Amphetamine / cocaine OD
- Third nerve palsy
- Brain death
Causes of isolated third nerve palsy? Effect on pupil?
Microvascular (ischaemia)
- Caused by diabetes / hypertension.
- Painless, pupil not affected
Compressive
- Caused by PCA aneurysm / raised ICP
- Painful, pupil affected
What are some causes of cranial nerve palsies?
- Idiopathic
- Raised ICP (tumour / haemorrhage)
- Compression (aneurysm / tumour)
- Ischaemia (microvascular blockages)
- Infections (meningitis etc.)
What can cause Nystagmus?
- Congenital (inherited)
- Inner ear pathology
- MS
- Stroke
- Substance abuse (alcohol / pharmaceuticals)
- Head trauma
- Cerebellar disease
What is trigeminal neuralgia? What usually causes it?
- Paroxysmal attacks of stabbing pain
- Usually due to compression of trigeminal nerve (vascular abnormalities / tumours / raised ICP)
