Cranial Nerves Flashcards
What do cranial nerves supply?
Supply somatic and visceral motor and sensory information to the head
CN IX and X supply visceral sensory and motor innervation to neck, chest and abdomen
Which two cranial nerves are different to the rest in terms of the strucutres that they innervate?
CN IX and X
Supply visceral sensory and motor innervation to neck, chest and abdomen
List the cranial nerves?
Which cranial nerves are purely sensory?
Which are purely motor?
Which are mixed?
Sensory: 1, 2, 8
Motor: 3, 4, 6, 11, 12
Mixed/both: 5, 7, 9, 10
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What are cranial nerves connected to centrally?
Cranial nerve nuclei
Describe the broad organisation of cranial nerve nuclei?
Organised rostrally to caudally
Roughly organised in order of target tissues
Which cranial nerve nuclei are located in the brainstem?
Nuclei 3-12
How are the cranial nerve nuclei arranged in the brainstem?
6 columns either side of midline
Motor nuclei are located in the 3 columns close to midline
Sensory nuclei are located in the 3 lateral columns
Where are the motor nerve nuclei located in the brainstem?
3 columns close to midline
What are the three motor columns located in the brainstem?
Medial to lateral:
Somatic
Branchial
Visceral
Which cranial nerve nuclei are in the somatic motor column? Where in the brainstem are these nuclei located?
Extra-ocular muscles: CN 3, 4, 6
Tongue muscles: CN 12
Which cranial nerve nuclei are located in the branchial motor column? Where in the brainstem are they located?
Muscles of mastication: CN 5 (V3)
Muscles of facial expression: CN 7
Muscles of pharynx and larynx: CN 9, 10
What is the nucleus ambiguus? Where is it located?
Mostly a motor nucleus
Lies behind inferior olive in medulla
Contains nuclei of CN IX (stylopharyngeus) and X (levator palati)
Which cranial nerve nuclei lie in the visceral efferents motor column? Where in the brainstem are they located?
Motor innervation to smooth muscles: CN 3, 7, 9, 10
Where are the sensory nerve nuclei located?
In lateral 3 columns
What are the three sensory columns located in the brainstem?
Medial to lateral:
Visceral sensory
Somatic sensory
Special sensory
Which cranial nerve nuclei are located in the visceral sensory column? Where in the brainstem are they located?
Taste: CN 7, 9, 10
Autonomic: CN 9, 10
What is the Nucelus Solitarius? Describe its arrangement?
Nucelus for visceral sensation
Extends from pons to nucleus gracilis
Rostral: gustatory nucleus
Caudal: visceral sensory division
Which cranial nerve nuclei are in the somatic sensory column of the brainstem? Where are they located?
Sensation to face, mucosa of nose and mouth, cranial dura: CN 5
Skin behind ear and lining of EAM: CN 7, 9, 10
Which cranial nerve nuclei are located in the special sensory column of the brainstem? Where in the brainstem are they located?
Hearing and equilibrium: CN 8
Which cranial nerve nuclei arise from the midbrain? Which from the pons? Which from the medulla?
Rule of fours:
Midbrain: 3, 4
Pons: 5, 6, 7, 8
Medulla: 9, 10, 11, 12
Describe the locations of all of the cranial nerve nuclei in the brainstem and spinal cord?
Describe the olfactory nerve?
Sense of smell
Exits skull at cribiform plate
Describe the optic nerve?
Sight
Exits at optic canal
Formed from axons of ganlion cells in the retina
What is the optic nerve formed from?
Axons of ganglion cells in the retina
Describe the nerves of ocular motion?
CN 3, 4, 6
CN III innervates 4
CN IV innervates superior oblique
CN VI innervates lateral rectus
Act in a coordinated fashion to move the eyes
Exit skull at SOF
Describe the oculomotor nerve?
Motor: Innervates 4 extraocular muscles and elevates eyelid
PS: Innervates iris and ciliary muscle
Exits skull at SOF
Describe the passage of the nerves of ocular motion?
All 3 go through cavernous sinus and SOF
4 and 6 go through common tendinous ring
Which nerves exit the skull via the SOF?
3, 4, 6, V1
Describe the groups that cranial nerves exit the skull in? Why is this signifcant?
Nerves that exit the skull together will be affected by disease together
What does the trigeminal nerve innervate?
Sensory: innervates face and inside mouth
Motor: innervates muscles of mastication and tensor tympani
Describe the three divisions of the sensory division trigeminal nerve? What does each innervate?
V1: opthalmic
V2: maxillary
V3: mandibular
Which structure does the motor division of the trigeminal nerve travel with?
V3 division of sensory division of trigeminal nerve
(In picture, blue=sensory, red=motor)
Where do each of the sensory divisions of the trigeminal nerve exit the skull?
V1: SOF
V2: foramen rotundum
V3: foramen ovale
Describe the cranial nerves involved in the corneal blink reflex?
What is the reflex a test of?
Sensory: CN 6
Motor: CN 7
(both located in pons)
Used as a test of pontine function
What does the facial nerve innervate?
Motor: muscles of facial expression, stapedius muscle, part of digastric muscle
PS: lacrimal, sublingual and submandibular salivary glands
Taste: anterior 2/3 tongue and soft palate
Sensory: EAM
Describe the course of the facial nerve?
Describe the terminal branches of the facial nerve?
Temporal
Zygomatic
Buccal
Mandibular
Cervical
(Tall Zulus Bear Many Children)
Which structure do the terminal branches of the facial nerve pass through? Do they innervate this structure?
Parotid gland
Do NOT innervate it
Describe the vestibulocochlear nerve?
Responsible for hearing and balance
Exits skull via internal acoustic meatus
Through which foramen does the facial nerve exit the skull?
Internal acoustic meatus
Describe the nuclei of CN VIII in the brainstem?
Dorsal and ventral cochlear nuclei
Four vestibular nuclei
Describe the glossopharyngeal nerve?
Sensory: posterior 1/3 tongue, pharynx, middle ear and carotid body
Taste: posterior 1/3 tongue
PS: parotid gland
Motor: stylopharyngeus
Exits the skull via the jugular foramen
Describe the pathway of the glossopharyngeal nerve?
What does the vagus nerve innervate?
Motor: soft palate, pharynx, larynx, upper oesophagus, 1 tongue muscle (palatoglossus)
PS: pharynx to upper abdomen
Sensory: pharyn, larynx, oesophagus
Input from baroreceptors and chemoreceptors of aortic arch
Where does the vagus nerve exit the skull?
Jugular foramen
What are the sensory inputs and motor outputs involved in the gag reflex? What does this reflex test?
Sensory: CN IX to pharynx
Motor: CN X to pharynx
Test of medullary function
Are the motor cranial nerves upper or lower motor neurons?
Lower motor neurons
Describe the general symptoms of a lower motor neuron problems in a cranial nerve?
Flaccid paraslysis and atrophy
What is unique about the pathway of the spinal accessory nerve?
Nucleus is in spinal cord
ENTERS cranium via foramen magnum
Then travels with CN X roots and exits via jugular foramen
What does the spinal accessory nerve innervate?
Motor input to sternomastoid and upper part of trapezius
‘Shrug shoulders and turn head’
What happens if CN XI input is lost on one side?
Can’t turn head in opposite direction
Describe the hypoglossal nerve?
Motor innervation to intrinsic and extrinsic muscles of tongue (except palatoglossus)
Exits skull via hypoglossal foramen
What happens if CN XII input is lost on one side?
Tongue deviation
