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Flashcards in Innervations and reflexes Deck (94)
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1
Q

How many nerves are involved with the eye?

A

8

2
Q

What are the 8 nerves involved with the eye?

A
Facial CNVII
Abducens CNVI
Trochlea CNIV
Oculomotor CNIII
Short ciliary nerve
Optic nerve CNII
Trigeminal Ophthalmic nerve CNV1
Sympathetic motor/Long ciliary nerve
3
Q

What four nerve types are present in the eye?

A

Autonomic sensory
Autonomic parasympathetic
Autonomic sympathetic
Somatic motor

4
Q

Which two nerves provide sensory input from the eyes?

A

Optic nerve CNII

Trigeminal ophthalmic nerve CNV1

5
Q

What type of stimuli does the optic nerve (CNII) sense?

A

Light

6
Q

What type of stimuli does the ophthalmic nerve sense?

A

Mechanical

7
Q

What nerve supplies sensory information from the face?

A

Trigeminal

8
Q

What to branches of the trigeminal nerve are important for sensing the eye?

A

V1

V2

9
Q

What area of the face does the CNV1 nerve cover?

A

Forehead, upper eyelid, cornea, conjunctiva, bridge of nose.

10
Q

What area of the face does the CNV2 nerve cover?

A

Lower eyelid, maxilla, upper lip and side of nose

11
Q

How is the parasympathetic outflow described?

A

Craniosacral

12
Q

What cranial nerves provide the cranial outflow of the parasympathetics?

A

CNIII
CNVII
CNIX
CNX

13
Q

Which cranial nerves are parasympathetic?

A

CNIII
CNVII
CNIX
CNX

14
Q

Where do parasympathetic fibres synapse from presynaptic to postsynaptic?

A

Near their target organ

15
Q

Describe sympathetic axons

A

Presynaptic sympathetic spinal nerves exit SC between T1 and L2 where they synapse in the sympathetic chain next to the SC. From here postsynaptic splanchnic nerves go to organs and body wall.

16
Q

What are spinal nerves made up of?

A

Anterior and posterior rami

17
Q

Where are the sympathetic chains located?

A

Parallel to the SC

18
Q

What do splanchnic nerves do?

A

Supply the organs

19
Q

What does splanchnic mean?

A

Relating to viscera

20
Q

What happens at the cervical ganglia?

A

Postsynaptic splanchnic nerves to organs of the head branch off.

21
Q

Where do the postsynaptic splanchnic nerves to organs of the head branch off?

A

Cervical ganglia

22
Q

What are the postsynaptic splanchnic nerves to the organs of the head called?

A

Internal and external carotid nerves

23
Q

Where do the internal and external carotid nerves run?

A

Along the internal and external carotid arteries

24
Q

What do the internal and external carotid nerves form?

A

Periarterial sympathetic plexus

25
Q

What vessel carries the sympathetic nerve input to the orbit?

A

Ophthalmic artery

26
Q

What two tissues related to the eye receive sympathetic input?

A

Levator Palpebrae Superioris

Dilator pupillae

27
Q

How does the dilator pupillae receive its sympathetic input?

A

Long ciliary nerve

28
Q

What flows through the centre of the optic nerve?

A

Central artery and vein of the retina

29
Q

Where does the ophthalmic nerve enter the orbit?

A

Superior orbital fissure

30
Q

Where does the optic nerve exit the orbit?

A

Optic canal

31
Q

What three nerves supply somatic motor innervation to the eye?

A

Oculomotor CNIII
Trochlea CNIV
Abducens CNVI

32
Q

What does the abducens CNVI innervate?

A

Lateral rectus

33
Q

What does the trochlea CNIV innervate?

A

Superior oblique

34
Q

What does the oculomotor CNIII innervate?

A

Superior, inferior and medial rectus
Inferior oblique
Levator Palpebrae Superioris
Ciliary ganglion

35
Q

In addition to somatic motor what other fibres does the oculomotor CNIII carry and where to?

A

Parasympathetic to ciliary ganglion

36
Q

What arises from the ciliary ganglion?

A

SHort ciliary nerve

37
Q

What does the short ciliary nerve innervate?

A

Ciliary muscles

Sphincter pupillae

38
Q

Is the short ciliary nerve sympathetic or parasympathetic?

A

Parasympathetic

39
Q

What nerves synapse, arise and pass through the ciliary ganglion?

A

Synapse- CNIII
Arise- SHort ciliary
Pass through- Long ciliary

40
Q

In addition to the CNIII/Short ciliary nerve what other parasympathetic nerve is involved with the eye?

A

Facial CNVII nerve

41
Q

What does the facial CNVII nerve innervate?

A

Orbicularis oculi

Lacrimal gland

42
Q

Where does the oculomotor CNIII enter the orbit?

A

Superior orbital fissure

43
Q

What two features does the oculomotor (CNIII) nerve pass through to reach the eye?

A

Cavernous sinus

Superior orbital fissure

44
Q

How many divisions does the oculomotor nerve have?

A

2:
Superior
Inferior

45
Q

Which divisions of the oculomotor nerve (CNIII) supply which muscles?

A

Superior- SR and LPS

Inferior- IR, MR, IO and ciliary muscles

46
Q

Where does the CNIII (Oculomotor) arise?

A

Between pons and midline

47
Q

Where is the pons found?

A

Brainstem

48
Q

What does pons mean?

A

‘Bridge’

49
Q

What do ciliary nerves do?

A

Control iris and ciliary muscles

50
Q

What do ciliary muscles do?

A

Control lens focus

51
Q

What do iris muscles do?

A

Control aperture

52
Q

Where do all ciliary nerves pass through or arise from?

A

Ciliary ganglion

53
Q

What two types of ciliary nerve are there?

A

Long ciliary nerve

Short ciliary nerve

54
Q

Are long ciliary nerves sympathetic or parasympathetic?

A

Sympathetic

55
Q

Are short ciliary nerves sympathetic or parasympathetic?

A

Parasympathetic

56
Q

Where does the trochlear nerve CNIV enter the orbit?

A

Superior orbital fissure

57
Q

What does the trochlear nerve pass through?

A

Cavernous sinus

58
Q

Where does the abducens nerve CNVI enter the orbit?

A

Superior orbital fissure

59
Q

What does the abducens nerve pass through?

A

Cavernous sinus

60
Q

Which nerves enter the orbit through the superior orbital fissure?

A

Oculomotor CNIII
Trochlear VNIV
Ophthalmic CNV1
Abducens CNVI

61
Q

Which nerves pass through the cavernous sinus?

A

Oculomotor CNIII
Trochlear VNIV
Ophthalmic CNV1
Abducens CNVI

62
Q

Where does the optic nerve pass in relation to the cavernous sinus?

A

Superiorly

63
Q

Where does the facial CNVII nerve arise from?

A

Pons (in brain stem)

64
Q

Where does the abducens CNVI nerve arise from?

A

Pons/medulla junction

65
Q

Where does the trochlear CNIV nerve arise from?

A

Dorsal brain stem

66
Q

Where does the trigeminal CNV nerve arise from?

A

Pons

67
Q

Where does the optic nerve arise from?

A

Forebrain

68
Q

Which nerves are involved in the blink reflex?

A

CNV1
CNV
CNVII

69
Q

Describe the blink/corneal reflex

A

Adverse stimuli activates CNV1 fibres in cornea
CNV1 pass to trigeminal ganglion where they become CNV fibres
CNV fibres integrate in pons in brainstem
Pons activates CNVII fibres which cause closure of eyelid.

70
Q

Where is the ciliary ganglion located?

A

Posterior orbit

71
Q

Which nerve innervates the SR, IR, MR, IO, LPS and ciliary ganglia?

A

CNIII

72
Q

What nerve innervates the SO?

A

Trochlear

73
Q

What nerve innervates the LR?

A

Abducens

74
Q

What does the sphincter pupillae muscle do and what innervates it?

A

Constricts iris

Parasympathetic short ciliary nerve

75
Q

What does the dilator pupillae do and what innervates it?

A

Dilates iris

Sympathetic long ciliary nerve

76
Q

Describe the pupillae muscles?

A

Sphincter pupillae fibres form central ring round pupil

Dilator pupillae fibres radiate out like spokes

77
Q

What is a non-physiological dilation of the iris called?

A

Mydriatic

78
Q

What is a non-physiological constriction of the iris called?

A

Miotic

79
Q

is the facial CNVII nerve sympathetic or parasympathetic?

A

Parasympathetic

80
Q

What does the orbicularis oculi muscle do?

A

Closes the eye

81
Q

What do the ciliary muscles do?

A

Adjust the focus on the lens allowing for focus

82
Q

What happens when the ciliary muscles are relaxed?

A

The lens is stretched- good for distance vision

83
Q

What happens when the ciliary muscles are contracted?

A

The lens thickens- good for near vision

84
Q

What innervates the ciliary muscles?

A

Parasympathetic short ciliary nerve

85
Q

Can the ciliary muscles be actively relaxed?

A

No, can be actively contract but must wait for parasympathetic innervation to stop before can dilate

86
Q

What are the 6 reflex arcs it is important for us to know?

A
Maximal eyelid opening
Pupil contraction/dilation
Lens focusing
Lacrimation
Vestibulo-ocular reflex
Blink reflex
87
Q

When is maximal eyelid opening useful and what nerves control it?

A

Fight or flight

Somatic motor CNIII and sympathetic input

88
Q

What is pupil contraction/dilation used for and what nerves control it?

A

Regulate the amount of light entering the eye

Parasympathetic short ciliary nerve and sympathetic long ciliary nerve

89
Q

What is lens focusing used for and what nerve controls it?

A

Focusing on object at different distances

Parasympathetic short ciliary nerve

90
Q

What is lacrimation used for and what nerve controls it?

A

Lubricate, clean and protect the eyes

Parasympathetic CNVII

91
Q

What is the vestibulo-ocular reflex used for?

A

Eyes go opposite direction to head to keep them focused as head moves

92
Q

What is a pinpoint pupil and what can it be a sign of?

A

Fixed constricted pupil.

Opiate use

93
Q

What is a ‘Blown’ pupil and what can it be a sign of?

A

Fixed dilated pupil

CNIII damage

94
Q

What is accommodation?

A

When eyes converge the lens thickens and pupils constrict.