Autonomics of the Eye Flashcards

1
Q

What are the three divisions of the facial nerve?

A

CN VI Ophthalmic nerve

CN VII Maxillary nerve

CN VIII Mandibular nerve

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2
Q

What is innervated by the ophthalmic division of the facial nerve?

A

Upper Eyelid

Cornea

Conjunctiva

Skin of the root/bridge/tip of the nose

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3
Q

What is innervated by the maxillary division of the facial nerve?

A

Skin of the lower eyelid

Skin over the maxilla

Skin of the alla of the nose

Skin/mucosa of the upper lip

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4
Q

What is innervated by the mandibular division of the facial nerve?

A

Skin over the mandible and temporomandibular joint

APART from the angle of the mandible- C2, 3 spinal nerve

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5
Q

Describe the sensory (afferent) limb of the blink reflex?

A

Action potentials conduced from the cornea via CN VI branches to trigeminal ganglion, along CN V to pons

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6
Q

What is the central connection of the blink reflex?

A

Central CNS connection between CN V and CN VII

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7
Q

Describe the motor (efferent) limb of the blink reflex?

A

Action potential conducted in CN VII to eyelid- part of obicularis oculi

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8
Q

Where do sympathetic axons originate?

A

Autonomic centres in the brain

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9
Q

How to sympathetic axons supply organs?

A

Travel down spinal cord, exit T1-L2, travel to sympathetic chains, pass into spinal nerves pass into splanchnic nerves

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10
Q

Describe the path of pre-synaptic sympathetic axons to the eye?

A

Presynaptic axons from CNS exit spinal cord in T1 spinal nerve and synapse in superior cervical ganglion

  • superior
  • middle
  • inferior
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11
Q

Describe the path of post-synaptic sympathetic axons to the eye?

A

internal and external carotid nerves
Pass onto the surface of internal and internal carotid arteries, carried to organs of the head on the surface of their arteries

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12
Q

What does the ophthalmic artery carry?

A

Sympathetic axons to the orbit

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13
Q

Describe parasympathetic outflow?

A

Axons leave CNS in III, VII, IX & X to internal organs (not body wall)

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14
Q

How do parasympathetic axons get to the eye?

A

Parasympathetic ganglia in head to eye, lacrimal gland and salivary gland

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15
Q

What does the ciliary ganglion carry and supply?

A

CN III

Eye (Iris, ciliary muscles)

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16
Q

What does the pterygopalatine ganglion carry and supply?

A

CN VII

Lacrimal Gland

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17
Q

What does the otic ganglion carry and supply?

A

CN IX

Parotid gland

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18
Q

What does the submandibular ganglion carry and supply?

A

CN VII

Sublingual and submandibular gland

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19
Q

Where does the oculomotor nerve connect with the CNS?

A

Junction between midbrain and pons

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20
Q

Describe the path of the oculomotor nerve?

A

Passes through cavernous sinus and exits via superior orbital fissure

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21
Q

What supplies motor fibres to levator palpebrae superioris?

A

Oculomotor

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22
Q

What is the superior division of oculomotor supplying?

A

SR and LPS

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23
Q

What is the inferior division of oculomotor supplying?

A

MR, IR, IO and ciliary ganglion

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24
Q

What do the ciliary nerves supply?

A

Autonomic axons to control diameter of iris and refractive shape of lens

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25
What type of nerve fibre is carried by the long ciliary nerve?
Sympathetic | Somatic Sensory
26
What type of nerve fibre is carried by the short ciliary nerve?
Sympathetic | Parasympathetic
27
What is the ciliary ganglions purpose?
Allow synapsing of parasympathetics
28
What are the autonomic reflexes of the eye?
Maximal eyelid elevation/wide eye opening of fight or flight Pupillary dilatation/constriction adjusting light entry Accommodation reflex Lacrimation reflex Oculo-cardiac reflex Vestibulo-ocular reflex
29
What is the vestibulo-ocular reflex?
Turns the eye in the opposite direction to head gaze, allows you to stabilise gaze in head movement Connections- CN VIII, III, IV & VI
30
What is the oculo-cardiac reflex?
Reflex bradycardia in response to tension on extra-ocular eye muscles or pressure on eye Connections- CN CI & CN X
31
What are the sympathetic functions of the eye?
Open eyes wider Get more light into eyes Focus on far objects Emotional lacrimation
32
What are the parasympathetic functions of the eye?
Allow obicularis oculi to work Get less light into eyes (to protect the bright light or when asleep) Focus on far objects Reflex lacrimation to clean cornea
33
What kind of fibres does the levator palpebrae superioris contain?
Skeletal and Smooth Muscle
34
How do sympathetic fibres reach the levator palpebrae superioris?
- superior cervical sympathetic ganglion - internal carotid nerve - internal carotid plexus -axons carried on ophthalmic artery and on its branches to the orbital structures
35
What dilates the pupil?
Sympathetics
36
What is a mydriatic pupil?
Non-physiologically enlarged pupil
37
How are dilator pupillae fibres arranged?
Radially originate around the external circumference of the iris = FIXED insert around the internal circumference of the iris = MOBILE
38
What constricts the pupil?
Parasympathetics
39
What is a mitotic pupil?
Non physiologically constricted pupil
40
In what syndrome might you find a mitotic pupil?
Horners
41
What is a fixed pin-point pupil?
Pathological sign- opiate drugs
42
What is a fixed blown pupil?
CN III pathology
43
Where are sphincter pupillae fibres?
Encircle pupil | -around internal circumference of iris
44
Where do connections occur in the pupillary light reflex?
Midbrain
45
Describe the 1st neurone change in the pupillary light reflex?
1st neurones -retinal ganglion cells pass via the ipsilateral optic nerve to decussate in the optic chiasm, then synapse in the pretectal nucleus in the midbrain
46
What connects the lens to the ciliary body?
Suspensory ligaments
47
Describe the ciliary body
Muscular and vascular Smooth muscle like a sphincter at circumference
48
What happens to the ciliary muscle in far vision?
Relaxes - no parasympathetics - ligament tightens and lens flattens to focus
49
What happens to the ciliary muscle in near vision?
Contracts - parasympathetic - ligament relaxes and lens becomes spherical to focus on near objects
50
Are sympathetics involved in changing lens shape?
NO
51
What are the three components of the accommodation reflex?
1. Bilateral pupillary constriction (CN III) 2. Bilateral convergence 3. Bilateral relaxation of lens
52
What is the role of bilateral pupillary constriction?
To prevent diverging light rays from hitting the periphery of the retina and causing a blurred image
53
What is the role of Bilateral convergence ?
Medial rotation of both eyes | Simultaneous movement of both eyes maintains single binocular vision
54
What causes bilateral relaxation of lens'?
The lens becomes spherical due to contraction of ciliary muscles (CN III)
55
What are basal tears?
Important in corneal health Clean/nourish and hydrate the avascular cornea Contain lysozyme
56
What is lysozyme
Enzyme that hydrolyses bacterial cell wall
57
What are reflex tears?
Extra tears in response to mechanical or chemical stimulation
58
What is the afferent limb involved in reflex tears?
CN VI from cornea/conjunctiva
59
What is the efferent limb involved in reflex tears?
Parasympathetic axons originating from CN VII
60
Describe the 2nd neurone change in the pupillary light reflex?
``` 2nd neurones (bilateral) -located entirely within the midbrain and connect the pretectal nucleus to the next synapse in the dinger westphalia nucleus (the location of the cell bodied of the parasympathetic axons of CN III) ```
61
Describe the 3rd neurone change in the pupillary light reflex?
3rd neurones | - pass from the EW nucleus, via the CN III then its inferior division to synapse in the ciliary ganglion
62
Describe the 4th neurone change in the pupillary light reflex?
4th neurones | -short course in the ciliary nerves to sphincter pupillae muscles
63
What are the two nerves involved in lacrimation?
Facial and trigeminal