Orbital Autonomics Flashcards Preview

Ophthalmology Anatomy > Orbital Autonomics > Flashcards

Flashcards in Orbital Autonomics Deck (65):
1

What is the suspensory ligament?

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

2

What are the two attachments of the suspensory ligament?

Zygoma
Lacrimal

3

How could a fractured zygoma lead to double vision?

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

4

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

Infraorbital NVB within infraorbital canal can be damaged
Contains infraorbital nerve (branch of CN V2) which supplies parts of the face

5

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

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

6

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

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

7

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

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

8

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

Great Auricular Nerve
Spinal nerves C2 and C3

9

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

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

10

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

Palpebral part = Allows you to blink eyes gently
Orbital part = Allows you to scrunch your eyes

11

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

Palpebral

12

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

Ganglion of sympathetic trunk
Acetylcholine

13

Where do postsynaptic sympathetic axons synapse?

Target organ
Noradrenaline

14

What is the pathway of sympathetic axons for the orbit?

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

15

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

Parasympathetic ganglion within the target organ
Acetylcholine

16

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

Target organ
Acetylcholine

17

Through which nerves do all parasympathetic axons leave the CNS?

CN III
CN VII
CN IX
CN X
Sacral spinal nerves

18

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

Synapse at ciliary ganglion in the orbit
To the eye

19

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

Synapse at teragopalatine ganglion
To the lacrimal gland

OR

Synapse at submandibular ganglion
To the submandibular and sublingual salivary glands

20

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

Synapse at the otic ganglion
To the parotid salivary gland

21

What are the functions of CN III?

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

22

Where does CN III connect with the CNS?

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

23

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

Superior Orbital Fissure

24

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

Superior rectus
Levator palpebrae superioris

25

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

Medial rectus, inferior rectus, inferior oblique

26

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

Inferior

27

What is contained within the long ciliary nerve?

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

28

What is contained within the short ciliary nerve?

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

What is the function of the ciliary nerves?

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

30

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

Long ciliary nerve
First part of the afferent limb

31

What are the autonomic reflexes of the eye?

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

32

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

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

33

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

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

34

What are the sympathetic functions on the orbit?

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

35

What are the parasympathetic functions on the orbit?

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

36

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

Skeletal muscle
Smooth muscle

Smooth muscle = under non-voluntary sympathetic control

37

How do postsynaptic sympathetic fibres reach levator palpebrae superioris?

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

38

Which direction are the fibres of dilator pupillae?

Radial

39

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

Origin (fixed) = External circumference of iris
Insertion (mobile) = Internal circumference fo iris

40

What controls the dilation of the pupil?

Sympathetics
In dim light, fight or flight, sick patient

41

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

Mydriatic pupil
Mydriatic drugs

42

What is the arrangement of the sphincter pupilae fibres?

Encircling the internal circumference of the iris

43

What controls the constriction of the pupil?

Parasympathetics
In bright light, rest and digest

44

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

Miotic pupil
Horner's Syndrome (sympathetic failure -> no counter to parasympathetics -> uncontrolled constriction)

45

What might a fixed "pin point" pupil be a sign of?

Serious pathology
E.g. opiate drugs

46

What might a fixed "blown" pupil be a sign of?

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

47

Is the pupillary light reflex unilateral or bilateral?

Bilateral

48

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

Stimulated eye = Direct light reflex
Non-stimulated eye = Consensual light reflex

49

What aerated components of the pupillary light reflex?

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

50

How many neurones are involved in the pupillary light reflex?

Four

51

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

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

52

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

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

53

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

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

54

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

Bilaterally
Course in short ciliary nerves to sphincter pupillae muscles

55

How is near vision brought about?

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

56

How is far vision brought about?

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

57

What is the accommodation reflex?

Response to near vision form far vision

58

What are the three components of the accommodation reflex?

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

59

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

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

60

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

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

61

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

Lens becomes spherical de to contraction of ciliary muscles

62

What are the three kinds of tears?

Basal tears
Reflex tears
Emotional tears

63

What is the purpose of basal tears?

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

64

What is the path of reflex tears?

Afferent limb = CN V1
Efferent limb = Parasympathetic axons from CN VII

65

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

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