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Ophthalmology > week 1 anatomy eye autonomics > Flashcards

week 1 anatomy eye autonomics Flashcards

1
Q

what are the three division of the trigeminal nerve called?

A

ophthalmic V1
maxillary V2
mandibular V3

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2
Q

what does the ophthalmic nerve supply?

A 
upper eyelid
cornea
conjunctiva
skin of the root/bridge/tip of the nose
(SENSORY)
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3
Q

what does the maxillary nerve supply?

A 
skin of the lower eyelid
skin over the maxilla
skin of the ala of the nose
skin/mucosa of the upper lip
(SENSORY)
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4
Q

what does the mandibular nerve supply?

A

skin over the mandible and temporomandibular joint
apart from the angle of the mandible – supplied by C2,3 spinal nerves
(SENSORY)

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5
Q

what is the purpose of the blink (corneal) reflex?

A

to wash away foreign body, nourish cornea,stops eye drying out

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6
Q

describe in detail the blink reflex

A

Action potentials conducted from cornea via CN V1 branches
To trigeminal ganglion, then along CN V
To pons

Central CNS connections between CN V and CN VII

Motor (efferent) limb:
Action potentials conducted via CN VII
To eyelid part of orbicularis oculi

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7
Q

what are the organs of the head?

A

Skin
sympathetic innervation of arterioles of the head
sympathetic innervation of sweat glands
sympathetic innervation of arrector muscles

Brain
insensitive
no motor function (muscle!)

Eyes
anterior surface sensitive to touch: somatic-V1
smooth muscle of iris (pupil diameter)
smooth muscle of the ciliary body associated with the lens (focussing)

Lacrimal Glands (lacrimal fluid production – tears)

Salivary Glands (saliva production)

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8
Q

what is the route taken by sympathetic ganglions to reach the organs of the body/head & neck (in general)

A

Originates from autonomic centres in the brain

Passes down spinal cord

Exits spinal cord with T1-L2 spinal nerves

Travel to sympathetic chains running the length of vertebral column

Pass into all spinal nerves (anterior and posterior rami)

Pass into splanchnic nerves to eventually supply organs

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9
Q

Describe the route taken by sympathetic axons to reach the smooth muscle/ arterioles/ lacrimal gland of the orbit (in particular)

A

presynaptic sympathetic axons from CNS:
-exit spinal cord in T1 spinal nerve

  • ascend within sympathetic trunk
  • synapse in superior cervical sympathetic ganglion

post-synaptic sympathetic axons :
-enter internal and external carotid nerves

  • pass onto surface of the internal & external carotid arteries
  • carried to the organs of the head on the surface of the branches of these arteries
  • ophthalmic artery carries sympathetic axons into the orbit
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10
Q

describe the route taken by parasympathetic ganglions to reach the organs of the body/head & neck (in general)

A

All parasympathetic axons leave the CNS via cranial nerves III, VII, IX & X and via sacral spinal nerves

Craniosacral outflow

Internal organs, not body wall

Vagus nerve supplies organs of the neck, chest and abdomen as far as the mid-gut

Sacral spinal nerves ‘carry’ parasympathetic axons to the hindgut, pelvis and perineum

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11
Q

Describe the route taken by parasympathetic axons to reach the smooth muscle/ arterioles/ lacrimal gland of the orbit (in particular)

A

All parasympathetic axons leave the CNS via cranial nerves III, VII, IX & X (and via the spinal nerves)

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

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12
Q

where does the oculomotor nerve connect with the CNS? where does it pass through?

A

at junction between midline and pons.

Passes through cavernous sinus

Exits via superior orbital fissure

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13
Q

what does CN III supply

A

Somatic motor to superior (SR), medial (MR) & inferior rectus (IR) and inferior oblique (IO)

Somatic motor to levator palpebrae superioris (LPS)

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14
Q

CN III has presynaptic parasympathetic axons to the ciliary ganglion (superior and inferior) - which innervates what?

A

Superior division:
SR and LPS

Inferior division:
MR, IR, IO and ciliary ganglion

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15
Q

what do the ciliary nerves do?

A

supply autonomic axons to control diameter of iris & refractive shape of lens

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16
Q

what forms the first part of the blink reflex?

A

Long ciliary nerves

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17
Q

what do the long and short ciliary nerve consist of?

A

Long ciliary nerves:
sympathetic
somatic sensory

Short ciliary nerves:
sympathetic
parasympathetic

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18
Q

name some autonomic reflexes of the eye

A

maximal eyelid elevation / wide eye opening of fight or flight

pupillary dilation/constriction adjusting light entry: (pupillary) light reflex

focussing lens far & near vision: accommodation reflex

lacrimation reflex tear production

vestibulo-ocular reflex

oculocardiac reflex

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19
Q

what is the oculocardiac reflex

A

reflex bradycardia in response to tension on extraocular muscles or pressure on eye

CNS connections between CN V1 & CN X

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20
Q

what is the vestibulo-ocular reflex?

A

turns the eyes in the opposite direction to a head movement
stabilises gaze on an object during head movement
CNS connections between CN VIII & CNs
III, IV & VI

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21
Q

what are the sympathetic functions concerning the eye

A

opens eyes WIDER
gets MORE LIGHT in
focus on FAR OBJECTS
(?emotional lacrimation)

22
Q

what are the parasympathetic functions concerning the eye

A

allow orbicular oculi to work

get less light into eyes (to protect the retina from bright light or when asleep

focus on near objects

reflex lacrimation (to wash away the stimulant foreign body & clean the cornea)

23
Q

what opens eyes wider?

A

levator palpebrae superioris contains skeletal PLUS smooth muscle

24
Q

how to the postsynaptic sympathetic fibres reach levator palpebrae superioris?

A

superior cervical sympathetic ganglion → internal carotid nerve → internal carotid plexus → axons carried on the ophthalmic artery… → and on its branches to the orbital structures

25
Q

what dilates the pupil? when?

A

sympathetics

dim light or flight/fight

26
Q

non-physiologically enlarged pupil is called what?

A

mydriatic pupil

mydriatic drugs induce dilation of the pupil

27
Q

how does the dilator pupillae work? (dilates pupil)

A

Fibres run radially

around the external circumference of iris – fixed

insert around the internal circumference of iris - mobile

28
Q

parasympathetics do what to the pupil? when?

A

constrict

in bright light and “rest & digest”

29
Q

non-physiologically constricted pupil is called?

A

miotic pupil

component of Horner’s syndrome

30
Q

what does a fixed “Pin point” pupil mean?

A

serious pathological sign

e.g. opiate drugs

31
Q

what does a “fixed-dilated” (“blown”) pupil indicate

A

serious pathological sign

e.g. of CN III pathology

32
Q

where do the sphincter pupillae fibres encircle the pupil? (constricts pupil)

A

around the internal circumference of iris

33
Q

what is the special sensory (afferent) limb of the pupillary reflex

A

ipsilateral CNII - optic nerve

34
Q

what is the motor (efferent) limb of the pupillary reflex

A

bilateral via CNs III -

oculomotor nerves

35
Q

what is the pupillary light reflex

A

direct light reflex occurs in the stimulated eye

a consensual light reflex occurs in the non-stimulated eye

36
Q

describe the pupillary light reflex?

A 
1st neurones:
retinal ganglion cells
pass via ipsilateral optic nerve
decussate in optic chiasm
synapse in pretectal nucleus in midbrain
2nd neurones (bilateral):
located entirely within midbrain & connect pretectal nucleus to next synapse in                                  Edinger-Westphal nucleus  (location of cell bodies of parasympathetic axons of CN III)
3rd neurones (bilateral):
pass from EW nucleus, via CN III then its inferior division, to synapse in ciliary ganglion
4th neurones (bilateral):
course in short ciliary nerves to sphincter pupillae muscles
37
Q

how is the lens controlled?

A

suspensory ligament of lens connects the circumferences of the lens & the ciliary body

ciliary body
muscular and vascular
smooth muscle like a sphincter around circumference - ciliary muscle controls lens

38
Q

how does the lens focus on “far away objects”

A

no parasympathetics

ligament tightens & lens flattens to focus on an object in the distance

39
Q

the ciliary muscle contracts in “near vision”

A

parasympathetic

ligament relaxes & lens becomes spherical to focus on near objects

40
Q

what is the accommodation reflex

A

response to ‘near’ (and far)

41
Q

what are the 3 components of the accommodation reflex

A

bilateral pupillary constriction
bilateral convergence of both eyes towards midline
bilateral relaxation of the lens

42
Q

what controls the bilateral pupillary constriction in the accommodation reflex

A

parasympathetic constriction of sphincter pupillae

CNs III

43
Q

what controls the bilateral relaxation of the lens in the accommodation reflex

A

the lens becomes spherical due to contraction of the ciliary muscles
CNs III

44
Q

what controls the bilateral convergence of both eyes towards midline in the accommodation reflex

A

medial rectus

CNs III

45
Q

lacrimation two types of tears?

A

basal

reflex

46
Q

what are basal tears in lacrimation? what do they do?

A

important in corneal health
clean/nourish & hydrate the avascular cornea
contain lysozyme: - enzyme that hydrolyses bacterial
cell walls

47
Q

what are reflex tears in lacrimation? innervation?

A

extra tears in response to mechanical or chemical stimulation
afferent limb is CN V1 from cornea/conjunctiva
efferent limb is parasympathetic axons originating from CN VII

(emotional tears included)

48
Q

what causes the lacrimal gland to produce tears

A

branch CNVII, parasympathetic innervation

49
Q

what is Horner’s syndrome

A

Impaired sympathetic innervation to head and neck

50
Q

symptoms of Horner’s syndrome

A

miosis
ptosis
reduced sweating (anhydrosis)
increased warmth and redness

51
Q

what are the cause of Horner’s syndrome

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

Ophthalmology (17 decks)

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