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OPTHT801 > Cranial nerves > Flashcards

Cranial nerves Flashcards

1
Q

What is the function of the oculomotor nerve?

A

Oculomotor nucleus: supplies somatic motot function to all extraocular muscles except lateral rectus and superior oblique
Supplies ciliary muscle which affects accommodation
Edinger-Westphal nucleus: parasympathetic control of pupil via ciliary ganglion
(sympathetic comes separately via carotid artery)

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2
Q

Where is the CN III nucleus?

A

Midbrain
Level of superior colliculi
Ventral to aqueduct of Sylvius

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3
Q

What is the arrangement of the CN III nuclei?

A

Rostro-caudal
Rostral: Edinger-Westphal nucleus
Caudal: centrocaudal nucleus (supplies levator palpebrae)

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4
Q

What is special about the superior rectus nucleus?

A

Contralateral fascicle
Supplies opposite sides muscle (in reality the fibres cross so close it causes ipsilateral failure of elevation and paralysis of IO)

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5
Q

Where does the fascicle of CN III run and which arteries does it pass between?

A

Passes by red nucleus to exit in interpeduncular fissure

Passes between posterior cerebral and superior cerebellar artery, alongside posterior communicating artery

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6
Q

What are Webers, Benedikts, Nothnagels syndromes?

A

Webers: CN III plus contralateral limb weakness (corticospinal fibres)
Benedikts: CN III plus contralateral cerebellar tremor (red nucleus)
Nothnagels: CN III plus cerebellar ataxia (cerebellar peduncles)

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7
Q

Describe the cranial course of CN III

A

Exits midbrain via interpeduncular fissure
Pierces dura lateral to posterior clinoid process
Passes between free and attached borders of tentorium cerebelli
Runs in lateral wall (superiorly) of cavernous sinus to superior orbital fissure

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8
Q

Where does the oculomotor nerve sit in the superior orbital fissure?

A

In superior and inferior divisions
Superior above nasociliary nerve and inferior below
All within tendinous ring

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9
Q

What do the 2 divisions of CNIII supply?

A

Superior: Levator palpabrae, superior rectus

Inferior division: Inferior oblique, inferior rectus, parasympathetic fibres, medial rectus

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10
Q

What are the three branches of the CN III inferior division?

A

-Passes beneath optic nerve to medial rectus
-inferior rectus
-longest branch runs between IR and LR to inferior oblique
All enter muscle on ocular surface except branch to inferior oblique which enters posteriorly

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11
Q

What are the only fibres to synapse in the ciliary ganglion?

A

Parasympathetic fibres

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12
Q

What occurs in oculomotor palsy?

A

Down and out pupil
Ptosis
Mydriasis due to unopposed sympathetic input on pupil
Ischaemic: complete + pupil sparing
Posterior communicating artery aneurysm: incomplete, involves the pupil, pain

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13
Q

What are the functions of the trochlear nerve?

A

Supplies superior oblique
Depresses
Intorts
Abducts

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14
Q

What is special about CN IV?

A

Smallest number of axons
Longest intracranial course
Exits the dorsal aspect of midbrain
Only cranial nerve to decussate before innervating its target
No aneurysm can cause isolate CN IV palsy
Head trauma most common cause of injury
Mass lesions can damage it by stretching the nerve where it hooks over petrous temporal bone

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15
Q

Where is the nucleus of CN IV?

A

Lies in dorsal aspect of midbrain beneath cerebral aqueduct

Level of inferior colliculus

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16
Q

What is the course of CN IV in the brain?

A

Exits dorsally
Runs along tentorium in subarachnoid space
Nucleus adjacent to descending sympathetic pathways (check for Horner’s syndrome)
Runs between posterior cerebral and superior cerebellar arteries
Enters cavernous sinus below CN III

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17
Q

Where does CN IV run in the superior orbital fissure?

A

Superior to CN III

Inferior to frontal lacrimal and superior ophthalmic vein outside the tendinous ring

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18
Q

How does CN IV palsy present?

A

Vertical/torsional diplopia

Head tilt and chin down

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19
Q

What is the function of the abducens nerve?

A

Supplies lateral rectus
Abduction
Contains 2 types of cells. Motor neurons which control ipsilateral LR and interneurons which cross the midline connecting to the contralateral oculomotor nucleus (responsible for coordinated horizontal gaze)

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20
Q

Where is the nucleus of CN VI?

A

Pons on the floor of the 4th ventricle
Axons run ventrally around the pons
CN VII loops around abducens nerve nucleus within the pons therefore a pontine lesion with produce ipsilateral paralysis of lateral rectus and lower motor neuron facial nerve palsy

21
Q

What is the course of CN VI in the brain?

A

Exits at pontomedullary junction medial to the facial nerve
Runs upwards between pons and clivus
Makes a sharp turn to enter cavernous sinus at tip of petrosal bone
Enters cavernous sinus and runs with ICA then to superior orbital fissure

22
Q

Where does CN VI run in the superior orbital fissure?

A

Most inferior structure in tendinous ring

23
Q

How does abducens nerve palsy present?

A

Horizontal diplopia

Worse in the direction of gaze of the affected muscle

24
Q

What are the functions of cranial nerve VII?

A

Facial muscles
Submandibular and sublingual salivary glands, lacrimal gland
Taste from anterior 2/3 of the tongue
Skin of EAM and TM

25
Q

Where is the CN VII nucleus?

A

Found in the lower pons

Receives cortical inputs

26
Q

What are the other nuclei associated with the facial nucleus?

A

Superior salivary nucleus-parasympathetic
Nucleus tractus solitarius-taste
Spinal trigeminal nucleus-somatic afferent

27
Q

How does CN VII run in the brain?

A

Dorsal surface of the facial nucleus, run toward the rhomboid fossa and arch over the nucleus of the abducens nerve, forming facial caniculus
Then exits brain stem at cerebellar pontine angle
In close contact with anterior inferior cerebellar artery

28
Q

What is nervus intermedius?

A

Smaller nerve carrying non motor fibres that runs with main facial nerve
Passes to internal acoustic meatus
Joins main nerve at geniculate ganglion in the internal acoustic meatus

29
Q

How does CN VII run in the internal acoustic meatus?

A

Laterally, posteriorly then inferiorly

Leaving the skull via stylomastoid foramen

30
Q

What divisions of CN VII occur at the parotid gland?

A

Initially temporozygomatic division and cervicofacial division
Then becomes temporal, zygomatic, buccal, marginal mandibular and cervical

31
Q

What are the intracranial branches of CN VII?

A

Greater petrosal
Tympanic
Nerve to stapedius
Chorda tympani

32
Q

What does the greater petrosal nerve do?

A

Forms nerve of pterygoid canal

Provides parasympathetic secretomotor innervation to the lacrimal gland

33
Q

What does the chorda tympani do?

A

Taste of anterior 2/3 of the tongue
Parasympathetic to submandibular and sublingual glands
Joins lingual nerve

34
Q

What are the 3 main branches of the ophthalmic nerve?

A

Lacrimal
Frontal
Nasociliary (only one that passes through tendinous ring)

35
Q

What does the lacrimal nerve supply?

A

Lacrimal gland and upper eyelid

36
Q

What does the frontal nerve supply?

A

Splits into suprorbital and supratrochlear supplies the upper eyelid and medial forehead

37
Q

What does the nasociliary nerve supply?

A

Iris, choroid, ciliary body, cornea, pupil, eyelid, lacrimal gland

38
Q

What cavity does the maxillary division V2 run through?

A

Foramen rotundum
Enters pterygopalatine fossa
Enters orbit via inferior orbital fissure and becomes infraorbital nerve

39
Q

What are the branches of the maxillary nerve within the pterygopalatine fossa?

A 
Greater palatine nerve
Lesser palatine nerve
Nasal nerves
Pharyngeal branch
Nasopalatine nerve
Posterior superior alveolar nerves
Zygomatic nerve
40
Q

What is the branch of the maxillary nerve within the orbit?

A

Anterior superior alveolar nerve

41
Q

Which cavity does the mandibular nerve pass through to exit the brain?

A

Foramen ovale accompanied by a small motor root which then joins it

42
Q

Which nerves are in the anterior division of the mandibular V3 nerve?

A

All motor except one
Motor branches to muscles of mastications, medial pterygoid muscle, nerve to tensor palatini, tensor tympani, lateral pterygoid, 2 deep temporal nerves and nerve to masseter
Buccal nerve

43
Q

What are the branches of V3 prior to bifurcation?

A

Meningeal branch

Nerve to otic ganglion

44
Q

What are the branches of the posterior division of V3?

A

Auricotemporal nerve
Lingual nerve
Inferior alveolar nerve

45
Q

Where does CN IX emerge from the brain?

A

Between olive and inferior cerebellar peducnle

46
Q

What are the ganglions of CN IX?

A 
4 nuclei
Ambigious nucleus
Inferior salivary nucleus
Spinal nucleus of the trigeminal nerve
Solitary nucleus
47
Q

What are the branches of CN IX?

A 
Tympanic nerve
Carotid sinus nerve
Pharyngeal nerve
Muscular branch to stylopharyngeus
Tonsilar branch
Lingual nerves
48
Q

What are the functions of CNIX?

A

Sensory: posterior 1/3 of tongue, palatine tonsils, oropharynx, mucosa of misslde ear, pharyngotympanic tube and mastoid air cells, carotid body, taste for posterior 1/3 of tongue
Parasympathetic: parotid gland
Motor: stylopharyngeus and superior pharyngeal constrictor muscle (gag reflex)

49
Q

What do the posterior auricular and muscular branches of CN VII do?

A

Posterior auricular: occipital belly of occipitofrontalis

Muscular branch: posterior belly of digastric and stylohyoid

OPTHT801 (20 decks)

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