11 Orbit Anatomy Flashcards

1
Q

Avg volume of orbit

A

30 cm3

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2
Q

Avg depth of orbit

A

40-50 mm

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3
Q

Whats unique about anatomy of Asian eyelid

A

levator muscle lacks attachment to pretarsal skin resulting in absent pretarsal fold

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4
Q

What divides the lacrimal gland into 2 lobes

A

levator aponeurosis

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5
Q

What provides static support to lower lid

A

tarsal plate and its assoc medial and lateral canthal tendons

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6
Q

What provides dynamic support to lower lid

A

adhesion of pretarsal portion of orbicularis to tarsal plate

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7
Q

What structure in lower lid is analogous to levator aponeurosis of upper lid

A

capsulopalpebral fascia

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8
Q

what are the lower eyelid retractors

A

capsulopalpebral fascia and inferior tarsal muscle

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9
Q

What lines the posterior surface of eyelid

A

palpebral conjunctiva

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10
Q

what creates gray line in lid margin

A

muscle of riolan

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11
Q

what does the gray line divide

A

anterior and posterior lamella

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12
Q

What is the origin of the superior tarsal muscle (of Muller)

A

Deep side of the levator palpebrae superioris

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13
Q

What structure forms the medial canthal tendon

A

superficial head of the pretarsal fibers of the orbicularis oculi muscle

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14
Q

What are the 3 limbs of the medial canthal tendon

A

Superior, anterior, posterior

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15
Q

What limb of the medial canthal tendon covers the lacrimal fossa

A

superior

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16
Q

What is Whitnall’s tubercle

A

insertion site of lateral canthal tendon

17
Q

Which part of lacrimal system is most vulnerable to injury

A

The inferior canaliculus near the medial canthal tendon

18
Q

In relation to the anterior lacrimal crest, where are the anterior and posterior ethmoid arteries and the optic canal

A

24-12-6 rule

19
Q

What does the medial epicanthal fold cover?

A

lacrimal lake

20
Q

What is the fnc of the deep head of the orbicularis oculi?

A

inserts on posterior lacrimal crest and provides structural support to lid

21
Q

what happens with disruption of deep head of orbicularis oculi

A

lateral and anterior displacement of the medial canthal angle

22
Q

where does the lateral canthal tendon insert

A

orbital tubercle located 5 mm posterior to the lateral orbital rim

23
Q

what is the fleshy pink mound of tissue in medial canthus

A

lacrimal caruncle

24
Q

what glands are contained w/in tarsal plates

A

tarsal glands (meibomian)

25
which muscles are innervated by superior division of CN III
superior rectus and levator palpebrae superioris
26
which muscles are innervated by inferior division of CN III
inferior oblique, inferior rectus, medial rectus
27
What passes through superior orbital fissue
CN III, IV, VI, V1 | Superior ophthalmic vein
28
what is trichiasis
abnl direction of eyelashes
29
what is gross asymmetry of eye mvmt
heterotropia
30
What is an Argyll Robertson pupil
Accomodates but doesnt react (reacts to accomodation but not light) a/w syphilis