Cranial Fossae and Cranial Nerves Flashcards

1
Q

what are the notable features of the anterior fossa?

A

cribiform plate

crista galli

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2
Q

what are the notable features of the middle fossa?

A
foramen rotundum
foramen ovale
foramen lacerum
foramen spinosum
optic canal
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3
Q

what are the notable features of the posterior fossa?

A

groove for sigmoid dural venous sinus
jugular foramen
hypoglossal canal
foramen magnum

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4
Q

what is the route of the internal carotid artery?

A

through carotid canal in base of skull, crosses superior to the foramen lacerum as it exits the carotid canal

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5
Q

what passes through the foramen ovale?

A
O = otic ganglion
V = trigeminal nerve
A = accessory meningeal artery
L = lesser petrosal nerve
E = emissary vein
--> OVALE
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6
Q

what passes through the cavernous sinus?

A
internal carotid artery
occulomotor (CN III)
trochlear (CN IV)
opthalmic (CN V1)
maxillary (CN V2)
abducent (CN VI)
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7
Q

what is CN I?

A

olfactory nerve

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8
Q

what is the origin and route of CN I?

A

outgrowth of telencephalon
olfactory mucosa –> cribiform plate (ethmoid bone) –> synapse in olfactory bulb –> olfactory tracts –> pre-piriformis area of amygdala (primary olfactory cortex)

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9
Q

what is CN II?

A

optic nerve

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10
Q

what is the origin and route of CN II?

A

extension of diencephalon
retina –> optic canal –> form optic chiasm –> optic tracts –> geniculate body (thalamus) –> stritate area (visual cortex) (90% fibres) or medial root (non-geniculate) (10% fibres)

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11
Q

what is CN III?

A

oculomotor

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12
Q

what is the route of CN III?

A

midbrain –> superior orbital fissure –> orbit

runs in lateral wall of cavernous dural venous sinus, through annular ring

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13
Q

what does CN III innervate?

A

motor: inferior oblique, superior, inferior and middle rectus and levator palpabrae
parasympathetic: sphincter pupillae and ciliary muscle
superior division: levator palpabrae and superior rectus

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14
Q

what is CN IV?

A

trochlear

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15
Q

what is the route of CN IV?

A

midbrain –> superior orbital fissure –> orbit

runs in lateral wall of cavernous DVS, outside annular ring

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16
Q

which is the only CN from the posterior surface of the midbrain, has the longest intercranial (dural) root of all CNs and who’s fibres all cross to the opposite side?

A

CN IV

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17
Q

what does CN IV give motor fibres to?

A

superior oblique

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18
Q

what is CN V?

A

trigeminal

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19
Q

what are the 3 divisions of CN V?

A

CN V1 = opthalmic
CN V2 = maxillary
CN V3 = mandibular

20
Q

what is the roue of CN V?

A

originates from pons

forms a ganglion and divides into it’s 3 divisions

21
Q

what is the route of CN V1?

A

enters orbit through superior fissure

runs in lateral wall of cavernous DVS

22
Q

what does CN V1 supply?

A

general sensory to eye, lacrimal gland, eyebrow, forehead skin, nose etc.

23
Q

what is the route of CN V2?

A

enters pterygopalatine fossa through foramen rotundum

runs in lateral wall of cavernous DVS

24
Q

what does CN V2 supply?

A

general sensroy to skin of cheek, lower lid, upper jaw and teeth, side of nose, mucosa of mouth etc.

25
Q

what is the route of CN V3?

A

through foramen ovale to inferior surface of the base of skull

26
Q

what does CN V3 supply?

A

sensory: ear canal, parotid gland, lower jaw and teeth
motor: muscles of mastication, anterior belly of digastric, mylohyoid, tensor tympani, veli tensor palatini

27
Q

what is CN VI?

A

abducens

28
Q

what is the route of CN VI?

A

pons –> superior orbital fissure –> orbit

passes through cavernous DVS w/ICA, through annular ring

29
Q

what does CN VI innervate?

A

motor to lateral rectus

30
Q

what is CN VII?

A

facial

31
Q

what is the route of CN VII?

A

pons –> internal acoustic meatus –> temporal bone

motor fibres of facial expression exit via stylomastoid foramen

32
Q

what does CN VII give rise to?

A

major branches before parotid: greater petrosal nerve, stapedial nerve and chorda tympani
branches in parotid gland: temporal, zygomatic, buccal, mandibular and cervical + posterior auricular nerve (before parotid) (to muscles of facial expression)

33
Q

what does CN VII supply?

A

muscles of facial expression
stapedius
stylohyoid
posterior belly of digastric

34
Q

what is CN VIII?

A

vestibulocochlear

35
Q

what is the route of CN VIII?

A

pons/medulla oblongata –> internal auditory meatus –> vestibular/auditory apparatus
vestibular part: cerebellum, CN III, IV, VI and spinal tracts
cochlear part: inferior colliculi, medial geniculate nucleus of thalamus to auditory cortex

36
Q

what is CN IX?

A

glossopharyngeal

37
Q

what is the route of CN IX?

A

medulla oblongata –> jugular foramen

38
Q

what does CN IX supply?

A

parasympathetic: parotid, buccal and labial glands
motor: pharyngeal plexus and stylopharyngeus
sensory: post. 1/3rd tongue (incl. taste), soft palate, pharynx, tympanic cavity and membrane, pharyngotympanic tube, external ear and auditory canal

39
Q

what is CN X?

A

vagus

40
Q

what is the route of CN X?

A

medulla oblongata –> jugular foramen

cranial, cervical, thoracic and abdominal distribution

41
Q

what does CN X supply?

A

motor: pharyngeal plexus, soft palate and larynx
parasympathetic: thoracic and abdominal viscera
sensory: dura (post-cranial fossa), ear, external auditory canal, lower pharynx, laryngeal mucosa, thoracic and abdominal viscera

42
Q

what is CN XI?

A

(spinal) accessory

43
Q

what is the route of CN XI?

A

spinal cord –> foramen magnum –> joins ‘cranial root’ (part of CN X) –> jugular foramen

44
Q

what does CN XI supply?

A

motor to trapezius and sternocleidomastoid

45
Q

what is CN XII?

A

hypoglossal

46
Q

what is the route of CN XII?

A

medulla oblongata (ant. to olive) –> hypoglossal canal –> root of tongue above hyoid bone

47
Q

what does CN XII supply?

A

motor to all intrinsic muscles of the tongue and all extrinsic except palatoglossus