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2 Ophthalmology > Reflexes of the Orbital Region > Flashcards

Reflexes of the Orbital Region Flashcards

1
Q

what are the 3 divisions of the trigeminal nerve (CNV)

A

V1- opthalmic
V2- maxillary
V2- mandibular

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2
Q

what does the ophthalmic nerve innervated (V1) (sensory)

A

upper eyelid
cornea
conjunctiva
skin of the root/bridge/tip of the nose

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3
Q

what does the maxillary nerve innervate (CNV2) (sensory)

A

skin of the lower eyelid
skin over maxilla
skin over the ala of the nose
skin/mucosa of upper lip

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4
Q

what does the mandibular nerve (cNV3) innervate (sensory)

A

skin over mandible and temporomandibular joint (apart from angle of the mandible)

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5
Q

what foramen does the ophthalmic nerve travel through

A

supraorbital fossa

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6
Q

what foramen does the maxillary nerve travel through

A

infraorbital fossa

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7
Q

What is the sensory component of the ‘blink reflex’

A

CNV1 - The ophthalmic nerve

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8
Q

what is the pathway of the action potential in the blink reflex

A

CNV1– trigeminal ganglion – along trigeminal nerve – to pons – to motor nerve (CNVII - facial)

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9
Q

what is the motor component of the blink reflex and what does it do

A

CNVII - facial nerve

causes the closure of the eyelid via the orbicularis oculi

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10
Q

at what level do sympathetic neurons leave the spinal cord

A

T1-L2

therefore thoracolumbar output as the sympathetic neurons follow T1-L2 nerves to get to the sympathetic chain

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11
Q

where do sympathetic axons go after the sympathetic chain

A

run out in all spinal nerves to the splanchnic nerves which take them to organs

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12
Q

what phrase describes the sympathetic nervous system

A

‘fight or flight’ segment of the autonomic nervous system

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13
Q

how do post synaptic sympathetic fibres make it from T1 up to the eye

A

synapse at the superior cervical sympathetic ganglion

travel up the internal and external carotids

pass onto the surface of the carotids

carried to organs of the head on the surface of the branches from the carotid artery

ophthalmic artery carries sympathetic axons into the orbit

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14
Q

where do parasympathetic axons leave the spinal cord

A

Via cranial nerves III. VII, IX and X as well as sacral spinal nerves

therefore known as cranialsacral outflow

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15
Q

what is phrase that describes the parasympathetic nervous system

A

‘rest and digest’ segment of the autonomic nervous system

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16
Q

what do the parasympathetic ganglia in the head supply

A

the eye
the lacrimal gland
the salivary glands

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17
Q

where does the occulomotor nerve connect with the CNS

A

between the midline and the pons

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18
Q

where does the oculomotor nerve exit the skull

A

superior orbital fissure

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19
Q

what does the oculomotor nerve provide somatic motor innervation to

A 
Superior rectus 
medial rectus 
inferior rectus 
inferior oblique 
elevator palpebrae
20
Q

what do the ciliary nerves innervate

A

supply autonomic axons to control the diameter of the iris and refractive shape of the lens

21
Q

what are the long ciliary nerves

A

sympathetic
somatic sensory

first part of blink reflex

22
Q

what are the short ciliary nerves

A

sympathetic and parasympathetic

23
Q

what are the autonomic reflexes of the eye

A
  • wide eye - maximal eyelid elevation
  • pupillary dilation/constriction
  • focussing lens for far and near vision
  • Lacrimation reflex tear production
  • vestibulo-ocular reflex (stabilises gaze during head movement)
  • oculocardiac reflex (bradycardia in response to tension on the eye)
24
Q

what are the functions of the sympathetic nervous system on the eye

A
  • opening eyes wider
  • gets more light into eyes (dilation)
  • focuses on far objects
  • emotional lacrimation
25
Q

functions of the parasympathetic system on the eye

A
  • lets less light into the eye (constriction)
  • focuses eye on near objects
  • Reflex lacrimation (wash away foreign bodies)
  • allows orbularis oculi to work
26
Q

how do sympathetic fibres travel to the elevator palpebrae

A
  • superior cervical sympathetic ganglion
  • internal carotid
  • internal carotid plexus
  • carried on ophthalmic artery
  • carried on branches of ophthalmic artery

then opens eyes wider

27
Q

do sympathetic/parasympathetic fibres dilate the pupil

A

sympathetic

28
Q

what is a non-physiologically dilated pupil

A

mydriatic pupil

caused by mydriatic drug

29
Q

in what direction are the DILATOR papillae fibres arranged

A

radially

30
Q

do parasympathetics/sympathetics constrict the pupil

A

parasympathetics

31
Q

what is a non-physiologically constricted pupil

A

mitotic pupil eg. component of horners syndrome

32
Q

what is the sensory part of the pupillary light reflex

A

CN II optic nerve

33
Q

what is the motor part of the pupillary light reflex

A

Oculomotor nerve CN III

34
Q

what happens when one eye is stimulated by light

A

direct light reflex occurs in the stimulated eye

a consensual light reflex occurs in the non-stimulated eye

35
Q

what is the first neurone in the pupillary light reflex chain

A

retinal ganglion cells

pass via optic nerve to optic chasm

synapse in the pretectal nucleus in the midbrain

36
Q

what is the pathway of the second neurone in the pupillary light reflex chain

A

v small neurones in the midbrain which synapse in the Edinger Westphalia nucleus

37
Q

what is the path of the third neurone in the pupillary light reflex chain

A

from the Edinger Westphalia nucleus via CNIII to synapse at the ciliary ganglion

38
Q

what do the 4th neurones in the pupillary light reflex do

A

short ciliary nerves to the spinchter papillae muscles

39
Q

what ligament connects to the lens and the ciliary body

A

suspensory ligament

40
Q

what happens to the ciliary muscle when far vision is needed

A

it relaxes to flatten the lens to focus on objects in the distance

41
Q

what happens to the ciliary muscle when near vision is needed

A

it contracts so the suspensory ligaments relax and the lens becomes spherical

42
Q

what are basal tears

A

tears which clean/nourish and hydrate the avascular cornea

contain lysosome to kill bacteria

43
Q

what are reflex tears

A

extra tears in response to mechanical stimuli or chemical stimulation

sensed by ophthalmic nerve

motor component - CNVII (facial)

44
Q

what are emotional tears

A

happy, sad or frightened tears

45
Q

what are the symptoms of horners syndrome

A

miosis (constriction)
ptosis (drooping of upper eyelid)
reduced sweating (anhydrosis)
Increased warmth and redness

46
Q

what causes Horner’s syndrome

A

impaired sympathetic innervation to the head and neck

47
Q

what are some causes of compression of the cervical parts of the sympathetic trunk

A 
root of neck trauma 
carotid dissection 
internal jugular vein engorgement 
deep cervical node metastases 
pancoast tumour (lung apex)

2 Ophthalmology (16 decks)

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