Cranial Nerves Flashcards
How many cranial nerves are there
12 pairs
Causes of compression of the cranial nerves
Inflammation
Tumours
Fractures
Name the cranial nerves, from CN I - CN XII
Olfactory Optic Oculomotor Trochlear Trigeminal Abducent Facial Vestibulocochlear Glossopharyngeal Vagus Accessory Hypoglossal
Types of fibre that may be contained in cranial nerves
somatic motor autonomic motor visceral sensory general sensory special sensory
Function of somatic motor fibres
Supply striated muscles
Function of autonomic motor fibres
Cranial division of parasympathetic supply, innervates smooth muscle and glands
Function of visceral sensory fibres
Afferent inputs from pharynx, larynx, lung, heart etc.
Function of general sensory fibres
Afferent inputs from skin and mucous membranes e.g. touch, temperature, pain
Function of special sensory fibres
taste smell vision hearing balance
Function of olfactory nerve
Smell
Fibres in olfactory nerve
Special sensory
Pathway of olfactory nerve
Passes through foraminifera in cribriform plate of ethmoid bone and enters the olfactory bulb in the anterior cranial fossa
Consequence of a tear in the olfactory nerve
Anosmia
Where does the optic nerve enter the skull
Via optic canal
Optic nerves join to form
optic chiasm
Fibres from what half of the retina cross to form the optic tract?
Medial (nasal)
Type of fibre in the optic nerve
Special sensory
Section of the right optic nerve would cause blindness in what eye?
Right
Section of optic chiasm would cause what pattern of vision loss?
Bilateral hemianopia
Section of right optic tract would cause what pattern of vision loss?
Left homonymous hemianopia (blindness in left temporal and right nasal fields)
Path of oculomotor nerve
Emerges from midbrain and exits via superior orbital fissure
Fibre types in oculomotor nerve
Somatic motor
Visceral motor
Muscles innervated by somatic motor fibres of the oculomotor nerve
Extraocular muscles
Levator palpebrae superioris
Function of visceral motor fibres of oculomotor nerve
Parasympathetic innervation to pupil causing constriction and to ciliary muscle causing accommodation of the lens
Clinical term for drooping of the upper eyelid
Ptosis
Path of trochlear nerve
Emerges from dorsal surface of the midbrain and exits via superior orbital fissure
Type of fibre in trochlear nerve
Somatic motor
Path of abducent nerve
Emerges between pons and medulla and exits via superior orbital fissure