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Y2 LCRS Anatomy of the Head, Neck and Spine > orbit > Flashcards

orbit Flashcards

orbit: describe the boundaries of the orbit; describe the location, actions and nerve supply of the intrinsic and extra-ocular muscles (including consequences of nerve injury)

1
Q

what makes up the roof of the orbit (1 thing)

A

orbital plate of frontal bone

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2
Q

what makes up the floor of the orbit (1 thing)

A

orbital plate of maxilla

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3
Q

what makes up the lateral wall of the orbit (2 things)

A

zygoma, greater wing of sphenoid

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4
Q

what makes up the medial wall of the orbit (4 things)

A

frontal process of maxilla, lacrimal bone, orbital plate of ethmoid (lamina papyracea), lesser wing of sphenoid

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5
Q

what foramen lies above the orbit in the orbital plate of frontal bone

A

supraorbital foramen

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6
Q

what foramen lies below the orbit in the frontal process of maxilla

A

infraorbital foramen

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7
Q

what section of the orbit can be blown out by a squashball injury, and consequence

A

orbital plate of maxilla, causing eye to drop into cheek cavity (causing double vision)

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8
Q

3 orbital foramina

A

optic canal, inferior orbital fissure, superior orbital fissure

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9
Q

2 contents of optic canal

A

optic nerve (CN II) to back of globe, ophthalmic artery

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10
Q

2 contents of inferior orbital fissure

A

maxillary nerve (CN V2), infraorbital vessels

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11
Q

6 contents of superior orbital fissure

A

ophthalmic nerve (CN V1), oculomotor nerve (CN III), trochlear nerve (CN IV), abducens nerve (CN VI), ophthalmic vessels, sympathetic fibres

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12
Q

which bone is the optic canal embedded in

A

lesser wing of sphenoid bone

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13
Q

where does the superior orbital fissure lie

A

between the lesser and greater wings of sphenoid bone

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14
Q

what 2 bones form the inferior orbital fissure

A

sphenoid bone and maxilla

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15
Q

where does the maxillary nerve exit through the maxilla bone inferior to the orbit

A

infraorbital foramen

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16
Q

2 groups of extrinsic eye muscles, and how many of each

A

4 recti, 2 obliques

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17
Q

what are the 4 recti muscles

A

inferior, superior, medial, lateral

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18
Q

origin of recti muscles

A

back of orbit in common tendinous ring

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19
Q

where do recti muscles insert into the eye

A

sclera, 5mm behind corneal margin

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20
Q

nerve supplying inferior, superior and medial recti

A

oculomotor (CN III)

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21
Q

nerve supplying lateral rectus

A

abducens (CN VI)

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22
Q

what are the 2 oblique muscles

A

inferior, superior

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23
Q

origin of inferior oblique

A

orbital surface of maxilla

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24
Q

origin of superior oblique

A

body of sphenoid

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25
Q

where does inferior oblique insert onto eye

A

posterior/inferior quadrant

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26
Q

where does superior oblique insert onto eye, and via what

A

poserior/superior lateral quadrant of globe, via trochlea

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27
Q

nerve supplying inferior oblique

A

oculomotor (CN III)

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28
Q

nerve supplying superior oblique

A

trochlear (CN IV)

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29
Q

what is the muscle of the upper eyelid

A

levator papebrae superioris (LPS)

30
Q

origin of LPS

A

lesser wing of sphenoid

31
Q

where does LPS insert

A

superior tarsal plate and skin of eyelid

32
Q

nerves supplying LPS

A

oculomotor (CN III), sympathetic to smooth muscle

33
Q

what syndrome is associated with loss of sympathetic supply to head

A

Horner’s syndrome

34
Q

how does LPS present in Horner’s syndrome

A

ptosis (drooping upper eyelid)

35
Q

what is the most superior muscle of the orbit

A

LPS

36
Q

what is the second most superior muscle of orbit, below LPS

A

superior oblique

37
Q

what direction of eye movement does contraction of superior oblique cause

A

inferior abduction (down and out)

38
Q

what is the third most superior muscle of orbit, below LPS and superior oblique

A

superior rectus

39
Q

what direction of eye movement does contraction of superior rectus cause

A

superior (elevation); slight adduction

40
Q

what direction of eye movement does contraction of inferior oblique cause

A

superior abduction (up and out)

41
Q

what direction of eye movement does contraction of inferior rectus cause

A

inferior (down); slight adduction

42
Q

what direction of eye movement does contraction of lateral rectus cause (clinical test)

A

abduction

43
Q

what direction of eye movement does contraction of medial rectus cause (clinical test)

A

adduction

44
Q

how to clinically test between inferior rectus and superior oblique (both depress eye) - H test

A

get patient to adduct eye first, then depress, to test superior oblique; get patient to abduct eye first, then depress, to test inferior rectus

45
Q

how to clinically test between superior rectus and inferior oblique (both elevate eye) - H test

A

get patient to adduct eye first, then elevate, to test inferior oblique; get patient to abduct eye first, then elevate, to test superior rectus

46
Q

what is intorsion and extorsion

A

rotational movement by eye muscles

47
Q

4 nerves of orbit

A

optic (CN II), oculomotor (CN III), trochlear (CN IV), abducens (CN VI)

48
Q

what is the optic nerve made out of

A

ganglion cell axons from retina

49
Q

number of rami in oculomotor nerve

A

2

50
Q

what muscles does oculomotor nerve innervate

A

medial rectus, superior rectus, inferior rectus, inferior oblique, LPS

51
Q

what muscle does trochlear nerve innervate

A

superior oblique

52
Q

what muscle does abducens nerve innervate

A

lateral rectus

53
Q

where does trigeminal ganglion sit

A

Meckel’s cave, lateral to pituitary gland (this sits below optic chiasm)

54
Q

3 branches of ophthalmic division of trigeminal nerve (V1)

A

frontal, lacrimal, nasociliary

55
Q

what sinus wall do these nerves pass through, before reaching orbit

A

cavernous sinus

56
Q

location of cavernous sinus

A

either side of sphenoid bone

57
Q

what is on each side of cavernous sinus

A

folds of dura

58
Q

what artery passes through cavernous sinus

A

internal carotid artery to supply anterior part of brain

59
Q

what nerve doesn’t run in wall of cavernous sinus, and instead runs with internal carotid artery more medially

A

abducens nerve (V)

60
Q

4 nerve order in cavernous sinus wall (inferior to superior)

A

maxillary division of trigeminal nerve (V2), ophthalmic division of trigeminal nerve (VI), trochlear nerve (IV), oculomotor nerve (III)

61
Q

outcome if cavernous sinus thrombosis or infection

A

damage to nerves

62
Q

2 branches of frontal branch of V1 (ophthalmic division of trigeminal nerve), and location where it supplies sensory innervation to skin

A

supratrochlear, supraorbital (forehead through supraorbital foramen)

63
Q

3 branches of nasociliary branch of V1 (ophthalmic division of trigeminal nerve)

A

branch to ciliary ganglion, ethmoidal, infratrochlear

64
Q

location of ciliary ganglion

A

just behind globe of eye

65
Q

ANS division of ciliary ganglion

A

PSNS

66
Q

where are preganglionic fibres of ciliary ganglion located

A

in inferior ramus of oculomotor

67
Q

where are postganglionic fibres of ciliary ganglion located

A

in short ciliary nerves

68
Q

what 2 muscles do ciliary ganglion innervate

A

sphincter pupillae and ciliary muscle

69
Q

which artery supplies blood to orbital

A

ophthalmic artery

70
Q

what 6 things does ophthalmic artery specifically supply blood to

A

central artery of retina, muscular, ciliary, lacrimal, supratrochlear, supraorbital

71
Q

2 ophthalmic veins, and what they drain back into

A

superior (cavernous sinus; potential route of infection), inferior (pterygoid plexus; not into cranial cavity)

Y2 LCRS Anatomy of the Head, Neck and Spine (39 decks)

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