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Ophthalmology Anatomy > Orbital Autonomics > Flashcards

Orbital Autonomics Flashcards

1
Q

What is the suspensory ligament?

A

Thick fascial sling that holds the eyes just above the orbital floor
Supports both eyes at the same vertical level

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2
Q

What are the two attachments of the suspensory ligament?

A

Zygoma

Lacrimal

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3
Q

How could a fractured zygoma lead to double vision?

A

Fractured zygoma rotates medially towards the floor of the orbit
Suspensory ligaments attached to zygoma laterally
eye lowered towards orbital floor
Eyes in two different vertical planes
Diplopia

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4
Q

How could a fractured zygoma lead to a general sensory nerve deficit of the face?

A

Infraorbital NVB within infraorbital canal can be damaged

Contains infraorbital nerve (branch of CN V2) which supplies parts of the face

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5
Q

Which parts of the face get their general sensory supply from CN V1 (ophthalmic nerve)?

A

Upper eyelids
Cornea
Conjunctiva
Skin of roof, bridge and tip of nose

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6
Q

Which parts of the face get their general sensory supply from CN V2 (maxillary nerve)?

A

Lower eyelid
Skin over maxilla
Skin of ala of nose
Skin/mucosa of upper lip

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7
Q

Which parts of the face get their general sensory supply from CN V3 (mandibular nerve)?

A

Skin over mandible and temporomandibular joint (apart from angle of mandible)

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8
Q

What s the general sensory supply of the angle of the mandible?

A

Great Auricular Nerve

Spinal nerves C2 and C3

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9
Q

What is the pathway of the blink (corneal) reflex?

A

Afferent Limb
APs conducted centrally via CN V1 to trigeminal ganglion, then in CN V to pons

CNS connections between CN V and CN VII

Efferent Limb
APs conducted peripherally in CN VII to the eyelid part of obicularis oculi

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10
Q

What are the two components of obicularis oculi and what are their functions?

A

Palpebral part = Allows you to blink eyes gently

Orbital part = Allows you to scrunch your eyes

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11
Q

Which part of obicularis oculi is involved in the blink reflex?

A

Palpebral

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12
Q

Where do presynaptic sympathetic axons synapse and what is the neurotransmitter?

A

Ganglion of sympathetic trunk

Acetylcholine

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13
Q

Where do postsynaptic sympathetic axons synapse?

A

Target organ

Noradrenaline

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14
Q

What is the pathway of sympathetic axons for the orbit?

A

Descend in spinal cord
Exit in T1 spinal nerve
Ascend sympathetic trunk
Synapse in superior cervical sympathetic ganglion
Enter internal and external carotid nerves
Pass onto surface of internal and external carotid arteries
Carried to organs of the head on the surface of the branches of these arteries
Ophthalmic artery carries sympathetic axons into orbit

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15
Q

Where do presynaptic parasympathetic axons synapse and what is the neurotransmitter?

A

Parasympathetic ganglion within the target organ

Acetylcholine

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16
Q

Where do postsynaptic parasympathetic axons synapse and what is the neurotransmitter?

A

Target organ

Acetylcholine

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17
Q

Through which nerves do all parasympathetic axons leave the CNS?

A 
CN III 
CN VII 
CN IX 
CN X 
Sacral spinal nerves
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18
Q

What is the course of the parasympathetic axons in CN III?

A

Synapse at ciliary ganglion in the orbit

To the eye

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19
Q

What is the course of the parasympathetic axons in CN VII?

A

Synapse at teragopalatine ganglion
To the lacrimal gland

OR

Synapse at submandibular ganglion
To the submandibular and sublingual salivary glands

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20
Q

What is the course of the parasympathetic axons in CN IX?

A

Synapse at the otic ganglion

To the parotid salivary gland

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21
Q

What are the functions of CN III?

A

Somatic motor to superior rectus, medial rectus, inferior rectus and inferior oblique
Somatic motor to levator palpebrae superioris
Presynaptic parasympathetic axons to ciliary ganglion

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22
Q

Where does CN III connect with the CNS?

A

Near the midline at the junction between the midbrain and the pons

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23
Q

What is the base of the skull part of CN III’s course?

A

Superior Orbital Fissure

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24
Q

Which muscles are supplied by the superior branch of CN III?

A

Superior rectus

Levator palpebrae superioris

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25
Q

Which muscles are supplied by the inferior branch of CN III?

A

Medial rectus, inferior rectus, inferior oblique

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26
Q

Which branch of CN III takes parasympathetic axons to the ciliary ganglion?

A

Inferior

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27
Q

What is contained within the long ciliary nerve?

A

General sensory fibres from the cornea and conjunctiva

Postsynaptic sympathetic fibres from the superior cervical ganglion

28
Q

What is contained within the short ciliary nerve?

A

General sensory fibres from the cornea and conjunctiva
Postsynaptic sympathetic fibres from the superior cervical ganglion
Postsynaptic parasympathetic fibres from the superior cervical ganglion

29
Q

What is the function of the ciliary nerves?

A

Supply autonomic axons to control the diameter of the iris (and pupil) and the refractive shape of the lens

30
Q

Which ciliary nerve is involved in the blink (corneal) reflex?

A

Long ciliary nerve

First part of the afferent limb

31
Q

What are the autonomic reflexes of the eye?

A 
Maximal eyelid elevation 
Pupillary light reflex 
Accommodation reflex 
Lacrimal tear reflex 
Vestibulo-ocular reflex 
Oculocardiac reflex
32
Q

What is the vestibule-ocular reflex and which CNS connections are involved?

A

Turns eyes in opposite direction to head movement (stabilises gaze on an object during head movements)
CN VIII and CNs III, IV + VI

33
Q

What is the oculocardiac reflex and which CNS connections are involved?

A

Reflex bradycardia in response to tension on the extra ocular muscles/pressure on the yes
CN V1 and CN X

34
Q

What are the sympathetic functions on the orbit?

A

Opens eyes wider
Gets more light into eyes
Focus on far objects
Emotional lacrimation

35
Q

What are the parasympathetic functions on the orbit?

A

Allow obicularis oculi to work
Get less light not eyes
Focus on near objects
Reflex lacrimation

36
Q

Which muscle fibres are contained within levator palpebrae superioris, and which is responsible for the autonomic reflex?

A

Skeletal muscle
Smooth muscle

Smooth muscle = under non-voluntary sympathetic control

37
Q

How do postsynaptic sympathetic fibres reach levator palpebrae superioris?

A 
Superior cervical ganglion 
Internal carotid nerve 
Internal carotid plexus 
On ophthalmic artery 
On branches to orbital structures
38
Q

Which direction are the fibres of dilator pupillae?

A

Radial

39
Q

What is the origin and insertion of the fibres of dilator pupillae?

A

Origin (fixed) = External circumference of iris

Insertion (mobile) = Internal circumference fo iris

40
Q

What controls the dilation of the pupil?

A

Sympathetics

In dim light, fight or flight, sick patient

41
Q

What is the term for a non-physiologically enlarged pupil and what may cause this?

A

Mydriatic pupil

Mydriatic drugs

42
Q

What is the arrangement of the sphincter pupilae fibres?

A

Encircling the internal circumference of the iris

43
Q

What controls the constriction of the pupil?

A

Parasympathetics

In bright light, rest and digest

44
Q

What is the term for a non-physiologically contracted pupil and what might cause this?

A

Miotic pupil

Horner’s Syndrome (sympathetic failure -> no counter to parasympathetics -> uncontrolled constriction)

45
Q

What might a fixed “pin point” pupil be a sign of?

A

Serious pathology

E.g. opiate drugs

46
Q

What might a fixed “blown” pupil be a sign of?

A

Serious pathology

E.g. CN III pathology (inhibiting pupillary constricting action of parasympathetics in ciliary nerves)

47
Q

Is the pupillary light reflex unilateral or bilateral?

A

Bilateral

48
Q

What are the terms for the different reflexes in the pupillary light reflex?

A

Stimulated eye = Direct light reflex

Non-stimulated eye = Consensual light reflex

49
Q

What aerated components of the pupillary light reflex?

A

Afferent Limb = ipsilateral CN II
CNS Connections = In thalamus
Motor Limb = Bilateral via CN III

50
Q

How many neurones are involved in the pupillary light reflex?

A

Four

51
Q

What is the path of the 1st neurones of the pupillary light reflexes?

A

Retinal ganglion cells pass via ipsilateral optic nerve decussate in the optic chiasma
synapse in the pretactal nucleus in the midbrain

52
Q

What is the path of the 2nd neurones of the pupillary light reflexes?

A

Bilaterally
Located within midbrain
Connect pretectal nucleus to next synapse in Edinger Westphal nucleus (location of cell bodies of parasympathetic CN III axons)

53
Q

What is the path of the 3rd neurones of the pupillary light reflexes?

A

Bilaterally
Pass from Edinger Westphal nucleus
Via CN III and its inferior division
Synapse in ciliary ganglion

54
Q

What is the path of the 4th neurones of the pupillary light reflexes?

A

Bilaterally

Course in short ciliary nerves to sphincter pupillae muscles

55
Q

How is near vision brought about?

A

Ciliary muscle contracts (parasympathetics)
Suspensory ligament of lens relaxes
Lens becomes spherical
Focus on close objects

56
Q

How is far vision brought about?

A

Ciliary muscle relaxes (no parasympathetics)
Suspensory ligament of lens tightens
Lens flattens
Focus on distant objects

57
Q

What is the accommodation reflex?

A

Response to near vision form far vision

58
Q

What are the three components of the accommodation reflex?

A 
Bilateral pupillary constriction 
Bilateral convergence (medial rotation of both eyes) 
Bilateral relaxation of the lens
59
Q

What is the purpose of bilateral pupillary constriction in the accommodation reflex?

A

Prevents diverging light rays from hitting the periphery of the retina and resulting in a blurred image

60
Q

What is the purpose of bilateral convergence in the accommodation reflex?

A

Simultaneous movement of both eyes in opposite directions to obtain/maintain singular binocular vision

61
Q

What is the purpose of bilateral relation of the lens in the accommodation reflex?

A

Lens becomes spherical de to contraction of ciliary muscles

62
Q

What are the three kinds of tears?

A

Basal tears
Reflex tears
Emotional tears

63
Q

What is the purpose of basal tears?

A

Corneal health
Clean and hydrate avascular cornea
Contain lysozyme (hydrolyses bacterial cell walls)

64
Q

What is the path of reflex tears?

A

Afferent limb = CN V1

Efferent limb = Parasympathetic axons from CN VII

65
Q

What is the path of the parasympathetic axons to the lacrimal gland?

A

CN VII leaves CNS at internal acoustic meatus
Branches
Synapse at pterygopalatine ganglion
Branches of V2 then V1 carry the axons to the lacrimal gland

Ophthalmology Anatomy (3 decks)

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