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OPTHT801 > Autonomic nerves and visual deficits > Flashcards

Autonomic nerves and visual deficits Flashcards

1
Q

What things does the autonomic nervous system control in the eye?

A

Intrinsic muscles of the eye
Vasomotor function
Secretion of tears
Sweat glands of the face

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2
Q

What is the 3 neuron pathway?

A

1st part= hypothalamus
2nd order neurons arise in brainstem and intermediolateral cell column of spinal cord
Synpases with 3rd order neurons which are outside the central nervous system

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3
Q

What are the key functions of the hypothalamus?

A

Detects changes in internal and external environment
Sexual activity
Endocrine secretion
Posterior- SNS Anterior-PNS

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4
Q

Where is the hypothalamus?

A 
Anterior and lateral walls of 3rd ventricle
Extends anteriorly to lamina terminalis
Inferiorly to mammillary bodies
Superior border=hypothalamic sulcus
Lateral border=internal capsule
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5
Q

What are the nuclei of the hypothalamus?

A 
Anterior group (supraoptic, paraventricular and suprachiasmatic)
Middle group (tuberal, ventromedial, dorsomedial, lateral and arcuate)
Posterior group (mamillary and posterior)
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6
Q

Where does the hypothalamus receive afferent connections?

A 
Limbic
Cortex
Globus pallidus
Amygdala
Retina (influences photoendocrine function eg circadian rhythms)
Brainstem
Spinal cord
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7
Q

Where does the hypothalamus send its efferent connections?

A

Mamillothalaic tract
Periventricular nuclei
Supropticohypophyseal tract

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8
Q

What is the blood supply to the hypothalamus?

A

Anterior communication artery
Posterior communicating artery
Posterior cerebral artery
Venous drainage via internal cerebral vein

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9
Q

What is special about the PNS?

A

Tends to respond rapidly and locally
Less extensive than CNS
Ganglions are close to end organs
Cranial cervical and sacral outflow

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10
Q

Which 4 nuclei influence the eye?

A

Edinger Westphal nucleus (PNS)
Superior salivatory (PNS)
Inferior salivatory (PNS)
Superior cervical ganglion (SNS)

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11
Q

Which 4 ganglions influence the eye?

A

Ciliary (to the sphincter pupillae)
Pterygopalatine (to palate and lacrimal gland)
Submandibular (to floor of mouth)
Otic (to parotid)
All contain sensory, SNS and PNS but only PNS synapse

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12
Q

What are the differences between pre and post ganglionic fibres?

A

Preganglionic: cholinergic and myelinated
Postganglionic: unmyelinated (except short ciliary nerves), PNS fibres are cholingeric, SNS fibres are adrenergic

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13
Q

How are the fibres arranged in the occulomotor nerve?

A

CN III is parasympathetic
Cells associated with pupiloconstriction are located on more superficially and dorsomedially than those associated with ciliary contraction and accomodation

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14
Q

Describe the CN III pathway from ciliary ganglion

A

8-10 branches leave ciliary ganglion and divide into 15-20 short ciliary nerves (myelinated)
95% innervated ciliary muscle-> accommodation
5% innervate sphincter pupillae -> pupiloconstriction

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15
Q

What is the afferent stimulus to the edinger westphal nucleus?

A

Pupillary light reflex
Simultaneous and equal constriction to pupils in response to light
Synapse in pretectal nucleus

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16
Q

What is the pretectal nucleus?

A

Collection of small cells anterior to lateral margin of superior colliculus
Retinal fibres end in dorsomedial part so in dorsal compression there is loss of the light reflex but preservation of the near reflex ( Parinaud’s syndrome)

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17
Q

In light -near -dissociation which response is damaged?

A

Always the light response

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18
Q

What happens to parasympathetic fibres in the pretectal nucleus?

A

Decussate around periaquaductal grey matter
Half travel via posterior commisure to contralateral EWN
Half travel via medial longitudinal bundle to ipsilateral EWN

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19
Q

Which reflexes travel via cranial nerve III and EWN?

A

Pupillar light reflex

Accommodation convergence reflex (also with CNVI)

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20
Q

What is Adie’s syndrome and what causes it?

A

Pupillary response to light decreased/slow but accommodation is intact (absent acutely but recovers with abberant reinnervation of sphincter fibres)
Secondary to ciliary ganglionitis
90% have absent tendon reflexes but no peripheral neuropathy
Demonstrated with pilocarpine (anticholinergic)

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21
Q

Describe the course of parasympathetic fibres with the facial nerve

A

Start in superior salivatory nucleus-> CN VII exits pons -> geniculate ganglion (no synapse) -> facial canal of temporal bone -> splits into 2;
Some go via greater petrosal nerve-> medial cranial fossa.-> between 2 layers of dura-> foramen lacerum-> pterygopalatine ganglion
Some go via chorda tympani-> pars flaccida-> lingunal nerve-> submandibular ganglion

22
Q

Where does the ptergopalatine ganglion send fibres to?

A

Via maxillary nerve-> zygomatic nerve-> zygomaticotemporal nerve-> lacrimal gland
Via rami orbitales-> cavernous sinus->retro-orbital plexus-> rami oculares-> superior orbital fissure-> ophthalmic +ciliary arteries

23
Q

Why does intraocular pressure drop when the greater petrosal nerve/pterygopalatine ganglion is damaged?

A

All main orbital arteries are supplied by retroorbital plexus
Run in adventitia
10% are SNS but most are PNS (vasodilator)

24
Q

What are the afferents to the superior salivary nucleus?

A

Nucleus of solitary tract (salivation to taste)
Nucleus of trigeminal nerve (tearing to eye irritation)
Limbic system (emotional tearing)

25
Q

What role does CN IX have in the PNS?

A

Transports PNS to parotid gland (auricotemporal nerve), oropharynx (pharyngeal branch) and posterior 1/3 of tongue (lingual branch)

26
Q

Where do primary neurons run in the SNS?

A

First order: hypothalamus-> midbrain -> inferior cerebellar peduncle-> lateral spinothalamic tract -> lateral part of ventral reticular formation and intermediolateral colums of cervical cord

27
Q

Where do secondary neurons run in the SNS?

A

Arise in intermediolateral column (dilator centre of budge and waller)
Fibres to eye are T1
Travel through white rami to sympathetic trunk through stellate ganglion (no synapse) lies within C7 transverse process and the neck of the 1st rib
Ansa subclavia-> enclose subclavian artery-> inferior + middle cervical ganglion (no synapse)-> super cervical ganglion (synapse)
Then forms internal carotid nerve

28
Q

Where is the superior cervical ganglion?

A

Between internal jugular vein and internal carotid artery

29
Q

Where do 3rd order neurons run in the SNS?

A

Internal carotid nerve-> internal carotid plexus, splits into several branches;
Deep petrosal nerve/nerve of pterygoid canal
Branch for trigeminal ganglion,
Branch for abducens nerve
Branch for trochlear nerve
Branch for ophthalmic nerve/ nasociliary nerve
Short ciliary nerves
Branch for oculomotor> inferior orbital foramen -> Mullers muscle

30
Q

Where do the corticotympanic nerves run?

A

Posterior wall of carotid canal gives off these nerves, they join tympanic plexus in the middle ear and joined by tympanic branch of CN IX rejoins the carotid plexus

31
Q

What does the cavernous plexus supply?

A

SNS
Fibres are given to all nerves who enter
Goes to V1, and nasociliary nerve-> long ciliary nerve-> pupillodilator

32
Q

What does the SNS twig to ciliary ganglion do?

A

Become short ciliary nerves (vasoconstrictor to blood vessels and innervate melanocytes of uvea)
And joins ophthalmic artery and CN III and mullers muscle

33
Q

What are the external carotid fibres?

A

Post ganglionic fibres destined for facial structures

34
Q

Where do 1st order neurons synapse?

A

Travel down midbrain, pons, cerebellum and spinal cord to synapse at intermediolateral nucleus of lower cervical and upper thoracic spinal cord

35
Q

Describe the course of the deep petrosal nerve as it comes off the internal carotid plexus

A

Deep petrosal nerve becomes known as nerve of pterygoid canal, enters the pterygopalatine ganglion but does not synapse, joins the zygomatic nerve then the lacrimal nerve to supply the lacrimal gland

36
Q

Describe the course of the ophthalmic branch of the internal carotid plexus

A

Joins the nasociliary nerve + enters the orbita via superior orbital fissure
Then becomes long ciliary nerve which supplies cornea, iris and ciliary body

37
Q

Which receptors are present in the smooth muscle of sphincter pupillae?

A

Alpha 1 adrenoceptors

Atropine/phenylephrine dilate pupil by acting as sympathetic stimulants

38
Q

What type of visual loss occurs with damage to the optic nerve?

A

Almost any kind of unilateral field loss
Optic neuritis: 48% diffuse visual loss, 20% altitudinal, 8% cecocentral
Peripheral field constriction with preservation of colour and vision= nerve sheath process

39
Q

What type of visual loss occurs with damage to the optic chiasm?

A

Bitemporal loss, commonly incomplete and asymmetrical
Depends on pre/post fixed pituitary gland
Pre-fixed: homonymous hemianopia with central loss
Post fixed: Uniocular loss with RPAD
Lesion at junction of optic nerve and chiasm: junctional scotoma
Inferior chiasm: superior bitemporal field loss
Superior chiasm: Inferior bitemporal field loss

40
Q

What is Wilbrand’s knee?

A

Junction of optic nerve and chiasm

Fibres from inferonasal retina and contralateral eye loop anteriorly in the ipsilateral optic nerve

41
Q

What is band atrophy?

A

Temporal nerve fibres insert superiorly and inferiorly at the optic disc
Nasal fibres insert laterally to the optic disc
Nasal fibres are the temporal visual field
In bitemporal field defect, the nasal fibres of the optic disc atrophy
Causes band/bowtie pattern of atrophy

42
Q

What are the other symptoms of a compressive lesion at the optic chiasm?

A

Hemi field slide- breakdown of phoria

Post fixational blindness

43
Q

What are some causes of optic chiasm lesions?

A

Internal carotid artery aneurysm
Cavernous sinus mass
Meningiomas
Tuberculoma

44
Q

What type of visual loss occurs with damage to the optic tract?

A

Incongrous homonymous hemianopia
Contralateral to lesion
More posterior the lesion the more congruous the field loss

45
Q

What type of visual loss occurs with damage to the lateral geniculate nucleus?

A

Sectoranopia but very variable

46
Q

What type of visual loss occurs with damage to the optic radiation ?

A

Temporal:Classically in Meyer’s loop. Pie in the sky wedge defect
Parietal: incomplete homonymous hemianopia more dense in lower quadrants

47
Q

What type of symptoms occur with damage to the temporal lobe?

A

Auditory, memory processing
Contralateral hemisensory disturbance and mild hemiparesis
Taste smell and visual hallucinations
Complex partial seizures
Receptive dysphasia-wont understand instructions

48
Q

What type of symptoms occur with damage to the parietal lobe?

A 
Acalculia
Agraphia
Left-right disorientation
Finger agnosia
Spatial neglect
49
Q

What type of symptoms occur with damage to the occipital lobe?

A

Congrupus homonymous hemianopia
Macular area has dual blood supply so is often spared in infarct (posterior cerebral and middle cerebral artery)
Unformed visual hallucinations
Denial of blindness (anton’s syndrome)
Charles Bonnet syndrome -formed or unformed hallucinations

50
Q

What is posterior cortical atrophy?

A

Dementia beginning with visual symptoms
Difficulty reading and depth perception
Distortion of color and images
Get lost in familiar environments

51
Q

What occurs with lesions of visual association cortex>

A

Inability to name objects, recognise faces

OPTHT801 (20 decks)

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