Cranial Nerves Flashcards
How many pairs of cranial nerves are there?
12
What are cranial nerves prone to compression due to?
Inflammation, tumours or fractures
What do the symptoms due to problems with cranial nerves relate to?
The function of the nerves
What are the different kinds of fibres that cranial nerves may contain?
Somatic motor fibres (supply striated muscle)
Visceral motor fibres (cranial division of the parasympathetic supply innervates smooth muscles and glands)
Visceral sensory (afferent inputs from pharynx, larynx, heart, lungs, gut etc)
General sensory (afferent input from skin and mucous membranes)
Special sensory (taste, smell, vision, hearing and balance)
Are the cell bodies of sensory (afferent) fibres inside or outside of the CNS?
Outside
Are the cell bodies of somatic motor fibres inside or outside of the CNS?
Inside
Are the cell bodies of autonomic motor fibres inside or outside of the CNS?
Inside and outside
What are each of the cranial nerves called?
Olfactory (CN I)
Optic (CN II)
Oculomotor (CN III)
Trochlear (CN IV)
Trigeminal (CN V)
Abducent (CN VI)
Facial (CN VII)
Vestibulocochlear (CN VIII)
Glossopharyngeal (CN IX)
Vagus (CN X)
Accessory (CN XI)
Hypoglossal (CN XII)
What kind of fibres does the olfractory nerve carry?
Special sensory (smell)
What kind of fibres does the optic nerve carry?
Special sensory (vision)
What kind of fibres does the oculomotor nerve carry?
Somatic motor (extraocular muscles, superior, medial, inferior rectus and inferior oblique and eye lid - levator palpebrae superioris)
Visceral motor (parasympathetic to pupil causing contriction and to ciliary muscle causing accomodation of the lens)
What kind of fibres does the trochlear nerve carry?
Motor (eye movements)
What kind of fibres does the trigeminal nerve carry?
Mixed (sensation from face and mouth, controls muscles of mastication so sensory and motor)
What kind of fibres does the abducent nerve carry?
Motor (eye movement)
What kind of fibres does the facial nerve carry?
Mixed (muscles of facial expression, parasympathetic, taste)
What kind of fibres does the vestibulocochlear nerve carry?
Special sensory (hearing and balance)
What kind of fibres does the glossopharyngeal nerve carry?
Mixed (swallowing, sensation from tongue, parasympathetic)
What kind of fibres does the vagus nerve carry?
Mixed (muscles of the throat, parasympathetic, visceral sensory)
What kind of fibres does the accessory nerve carry?
Motor (soft palate, throat and neck)
What kind of fibres does the hypoglossal nerve carry?
Motor (tongue)
Where is the receptor for the olfractory nerve?
Olfactory epithelium of nasal cavity
What route does the olfactory nerve take?
Passes through foraminifera in cribiform plate of ethmoid bone and enters olfactory bulk in the anterior cranial fossa
Fracture of what can tear the olfactory nerve and cause anosmia (loss of smell)?
Cribiform plate
What is the pathway of the optic nerve?
1) Enters via optic canal
2) Nerve join to form optic chiasm
3) Fibres from medial (nasal) half of each retina cross to form optic tract
What does a secetion of right optic nerve cause?
Blindness through right eye
What does a section of optic chiasm cause?
Loss of periphery vision (bitemporal hemianopsia)