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Anatomy > The Orbit > Flashcards

The Orbit Flashcards

1
Q

the optic canal is a feature of which bone?

A

The Sphenoid Bone

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2
Q

What forms the medial wall of the orbital?

A

Portions of the ethmoid, lacrimal, frontal and sphenoid bones. Small portion of palatine

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3
Q

What forms the floor of the orbital?

A

The orbital surface of the maxilla (roof of the maxillary sinus)

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4
Q

What forms the lateral wall of the orbital?

A

The greater wing of the sphenoid bone and the orbital surface of the zygoma

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5
Q

What structures may be injured in a blowout fracture?

A

An injury that results in damage to the floor of the orbit and potentially to its
medial wall as well (ethmoid bone). The infraorbital neurovascular bundle
may be compromised; bleeding into the maxillary sinusis a consequence as
well as loss of sensory supply to the teeth, gums, gingiva of the maxilla as
well as cutaneous distribution to the cheek, lateral nose and upper lip. If the
ethmoid bone is involved, the lateral wall of the nasal cavity may be damaged
as well as the ethmoid air cells (paranasal sinuses) and potentially the
sphenoid sinus as well.

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6
Q

What is the common tendon of the four rectus muscles of the eye?

A

The annular tendon.

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7
Q

What direction do the superior and inferior oblique muscles move the eye?

A

Superior- down

Inferior- up

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8
Q

Name the innervation of the six ocular muscles

A

Superior rectus, inferior rectus, inferior oblique, medial rectus are all CNIII. The superior oblique is CN IV and the Lateral Rectus is CN VI

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9
Q

What is the principle behind the H test for the eye?

A

Position the such that the pupil is aligned with the tendon of the individual muscle to be tested.

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10
Q

How do you test the superior and inferior rectus muscles?

A

Have the patient gaze laterally and then ask them to look up (for superior) and down (for inferior)

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11
Q

How do you test the superior and inferior oblique muscles?

A

Have the patient gaze medially and ask them to look up (inferior) and down (superior)

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12
Q

What innervates the levator palpebrae

A

CN III the oculomotor nerve

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13
Q

What autonomics does the oculomotor nerve contain?

A

Preganglionic parasympathetics that synapse in the ciliary ganglion. The post ganglionic from the short ciliary nerves which supply the ciliaris(shape of lens) and the constrictor pupilllae muscles

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14
Q

What special coverings does the optic nerve contain?

A

Pia, arachnoid, and dura

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15
Q

What is the pneumonic to help remember the innervation of the ocular muscles?

A

SO4LR6AR3

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16
Q

What would happen if you knock out CN III

A

eye would be down and out (External strabismus). You would have ptosis (drooping eyelid), double vision (diplopia), Loss of ability to focus ( presbyopia) and inability to constrict pupil (Mydriasis)

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17
Q

What are the three main branches of CN V1?

A

Frontal, Nasociliary, and Lacrimal(only sensory to capsule of lacrimal, no secretomotor) which all terminate cutaneously.

18
Q

With what nerve do the afferent fibers involved in the corneal reflex travel

A

they travel in the long ciliary nerves which are branches of the nasociliary branch of CN V1. (The motor fibers come from facial)

19
Q

What supplies secretomotor to the lacrimal gland?

A

Parasympathetic fibers from facial (VII) nerve that travel via the zygomatic nerve (branch of V2) to the lacrimal nerve of V1

20
Q

What innervates the dilator pupil muscles?

A

Postganglionic sympathetics from the internal carotid plexus enter the orbit with branches of the opthalmic artery.

21
Q

where are the cell bodies of the sensory fibers in V1?

A

The semilunar ganglion

22
Q

What does the frontal nerve split into?

A

Supraorbital and supratrochlear

23
Q

what are the branches of the nasociliary nerve?

A

Posterior and anterior ethmoidal nerves, long ciliary nerves terminates as the infratrochlear nerve

24
Q

Where does the central artery of the retina branch off from and what is an important feature of it.

A

Branches off of the opthalmic artery and there are no anastomotic connections, so it needs to be intact.

25
Q

What do the branches of the opthalmic artery follow?

A

branches of CN V1

26
Q

What veins drain the area around the eye?

A

The superior and inferior opthalmic veins which drain into the cavernous sinus

27
Q

If a patient complains of intermittent flashes of light, what should you think?

A

Detached neural retina.

28
Q

What can cause papilledema, and what are the symptoms?

A

Elevation of the area around the optic disc (as seen with an ophthalmoscope);
it is caused by an accumulation of extracellular or interstitial fluid due to
impaired venous return. Interstitial fluid usually returned to the circulation by
the veins now remains, causing edema – suggest that the central vein of the
retina is compromised. Can be caused by increased CSF pressure in CN II

29
Q

What can cause an arteriovenous fistula in the in cavernous sinus and what are some symptoms?

A

A fracture at the base of the skull causes a tear in the internal carotid. Blood backs into superior opthalmic vein and the eye swells and pulses (pulsating exophthalmus)

30
Q

What separates the lateral and medial walls of the orbit?

A

The inferior orbital fissure

31
Q

What is Diplopia

A

Double vision

32
Q

What is Ptosis

A

Drooping of upper eyelid

33
Q

What is Presbyopia

A

Inability to focus/accomidate

34
Q

What is mydriasis

A

inability to constrict the pupil

35
Q

What controls pupil dilation? and how do these nerves reach the pupil?

A

Postganglionic sympathetic fibers from the carotid plexus enter the orbit with the opthalmic artery to innervate the dilator pupillae

36
Q

What nerves are involved in the corneal reflex?

A

V1 and VII

37
Q

What nerves are involved in the accommodation reflex?

A

Cr II (you need to see the objec) and Cr III (you need to use you ciliaris muscles to adjust focus)

38
Q

What nerves are involved in the Light Reaction or Pupillary Reflex?

A

Cr II (need to detect change in light) Cr III (need to use pupillae constrictor muscles to close pupil)

39
Q

What is the nasociliary branch of the V1 association with the ciliary ganglion?

A

Purely anatomical

40
Q

What is pulsating exophthalmos and what causes it?

A

A fracture at the base of the skull (Sphenoid) can cause rupture of the internal carotid and an arteriovenous fistula can form with the superior opthalmic vein. engorgement of all connect vessels cause the eye to protrude and pulse with the flow of the carotid.

41
Q

What structures might be affected from a tumor eroding through the roof of the bony orbit?

A

Anterior cerebral lobes, olfactory bulbs (Cr. I)

Anatomy (17 decks)

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