anatomy - neuro > cranial nerves > Flashcards

cranial nerves Flashcards

(46 cards)

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1
Q

what are the cranial nerves?

A
  • a set of **12 **paired nerves **arising directly **from the brain
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2
Q

where do the cranial nerves emerge from?

A
  • they emerge from the cranial cavity via the foramina or fissures in the cranium
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3
Q

what are the 2 main origins of cranial nerves?

A
  • The **cerebrum **( CN I & II)
  • The brain stem (CN III- XII)
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4
Q

where in the brain stem do the CN III- XII originate from?

A

* midbrain (pontine junction) - CN III - oculomotor
* **midbrain **- trochlear (IV) arises from posterior side of midbrain
* **Pons **- the trigeminal (3 branches) V
* **Medulla Oblongata **(IX - XI)

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5
Q

what are the 12 cranial nerves?

One Of Our Top Teachers Asked For Very Good Vinegar And Honey

A
  1. Olfactory
  2. Optic
  3. Oculomtor
  4. Trochlear
  5. Trigeminal
  6. Abducent
  7. Facial
  8. Vestibulocochlear
  9. Glossopharyngeal
  10. Vagus
  11. Accessory (spinal)
  12. Hypoglossal nerve
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6
Q

What is a motor (efferent) nerve?

A

carries information from the brain to the periphery

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7
Q

what is a sensory (afferent) nerve?

A
  • Carries information** from the periphery to the brain**
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8
Q

Define general somatic afferent

A

converys general sensation from the skin

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9
Q

Define** general visceral afferent **

A

converys general sensation from viscera

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10
Q

Define special somatic afferent

A

conveys senses derived from ectoderm eg sight balance

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11
Q

Define general somatic efferent

A

conveys motor innervation for skeletal muscles

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12
Q

Define general visceral efferent

A

conveys motor innervation for smooth muscle, cardiac muscle and glands

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13
Q

Describe the **olfactory nerve **

function

A
  • CN I
  • function : carries special sensory fibres for** sense of smell**
  • speciailised nerve fibres located in olfactory mucosa
  • these fibres** enter the cranial cavity** via the cribiform plate of ethmoid bone
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14
Q

what can happen if there is severe head trauma / injury to the anterior cranial fossa (hint - to do with olfactory nerve)

A
  • it can cause seperation of the olfactory bulb from the nerves
  • can cause anosmia - loss of sense of smell
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15
Q

what other cranial nerve also innervates the nasal mucosa and what is it’s function?

A
  • CN V
  • function - chemoreceptor - senses coldness
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16
Q

Describe the optic nerve (CN II)

A
  • special somatic afferent
  • transmits all visual information - including colour & brightness perception
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17
Q

what is the optic chiasm?

what is it formed from? function?

A
  • formed by merging fibers from the optic nerve
  • function - receives visual information from the optic nerve and **transmits this information to the optic tracts **
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18
Q

what is the CNII surrounded by?

A

it is surrounded by extensions of the cranial meninges and subarachnoid space - which is filled with CSF

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19
Q

what is the function of the visual pathway?

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A
  • the visual pathway transmits information interpreted from **visual light from the eyes to the visual cortex in the brain
20
Q

what is the** visual field**?

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A
  • the visual field is what is seen by a person with both eyes wide open and looking straight ahead
21
Q

Describe the visual pathway

the beginning - ie light - ocular bulb-retina-optic nerve - chiasm

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A
  • visual pathway begins with light entering the ocular bulb and being processed by the retina
  • information then passed on from the retina by the optic nerve which travels to the optic chiasm
22
Q

Describe the visual pathway** from the optic chiasm**

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A
  • from the optic chiasm, the axons are now called the optic tract
  • the axons then synapse at the** lateral geniculate nucleus**
23
Q

how do axons from the lateral geniculate nucleus reach the visual cortex of the brain?

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A

they travel via the optic radiation

24
Q

where are inputs from the right and left visual field carried by?

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A
  • information from the left visual field carried in right optic tract
  • information from right visual field carried in left optic tract
25
where does **oculomotor nerve CNIII** supply?
* this nerve supplies **all extra ocular muscles** of the eye** EXCEPT** the** lateral rectus and superior oblique **
26
what are the **functions of the oculomotor nerve**?
* eye movement * pupil constriction (through parasynpathetic innervation) * maintaining open eyelid NB - somatic efferent (motor) - as info goes from brain to periphery (eyes)
27
Describe the **trochlear nerve** CN IV
* motor innervation of the** superior oblique muscle -** like a pulley system (trochlear = pulley) * unique - exits from posterior side of brain stem
28
Describe the CN VI - abducens nerve
* provides motor innervation of the lateral rectus muscle * leaves brainstem at junction of pons and medulla
29
Describe the **trigeminal nerve** - CN V
*** mixed nerve** - carries both sensory and motor information * primary sensory nerve for face and anterior scalp * motor nerve for muscles of mastication and other small muscles * trigeminal = triplet
30
what **3 terminal nerves** does the sensory route of the trigeminal nerve CN V divide into?
* Ophthalmic nerve * maxillary nerve * mandibular nerve
31
Describe the **facial nerve **
* CN VII * supplies motor innervation to the muscles of facial expression * supplies parasympathetic innervation to the salivary glands, lacrimal glands, and mucous glands
32
Describe the **vestibulocochlear nerve** CN VIII
* carries special sensory fibres for hearing and balance * can be divided into 2 components - cochlear part (transmits auditory info to brain) and vestibular part (transmits info about balance to the brain)
33
Describe the glossopharyngeal nerve
* transmits sensory info from the carotid body & sinus, posterior third of tongue, oropharynx etc * carries special sensory fibres for taste for posterior 1/3 of tongue
34
what gland does the glossopharyngeal nerve innervate?
the parotid salivary gland
35
what does the **glossopharyngeal nerve** **arise from** and where does it** exit the cranial cavity**?
* arises from the medulla oblongata * exits the cranial cavity via the jugular foramen
36
Describe the **vagus nerve** CN X | vagus = wondering in latin
* most **widely distributed CN** *** mixed **nerve * provides sensory info to the **heart, lungs trachea, bronchi, pharynx ** and more... * also supplies **parasympathetic info** to **smooth muscle and glands** in the body
37
where does the vagus nerve arise from and where does it exit the cranial cavity?
* it arises from the medulla oblongata * exits via the jugular foramen
38
What 2 muscles does the spinal accessory nerve innervate?
* Trapeqius * SCM muscle in neck
39
where do the fibres of the spinal accessory nerve originate from?
the spinal cord
40
Describe the path of the accessory nerve
* it originates from the spinal cord and ascends into the cranial cavity via the foramen magnum * it then exits the cranial cavity via the jugular foramen where it innervates the 2 muscles
41
is the hypoglossal a motor or sensory nerve?
motor
42
Describe the hypoglossal nerve (CN XII)
* motor nerve * motor innervation to intrinsic and extrinsic muscles of tongue except for palatoglossus muscle
43
which cranial nerve innervates the palatoglossus muscle ?
vagus nerve
44
where does the hypoglossal nerve originate from and where does it exit the cranial cavity?
* it arises from the anterior surface of the medulla oblongata * it exits the cranial cavity via he hypoglossal canal
45
which of the cranial nerves are** mixed** nerves?
* trigeminal nerve * facial nerve * glossopharyngeal nerve * vagus nerve
46
what is a brachiomotor nerve?
-special motor to muscles from pharyngeal (brachial) arches
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