S2 Anatomy Exam 3: Orbit Dissector

Front 1

The ethmoid, a bone of the orbital plate, separates the cavity of the orbit from the _________________

Back 1

ethmoidal paranasal sinus
(ethmoidal air cells)

Front 2

The ethmoid is paper thin & ethmoidal sinusitis may result in what?

Back 2

orbital cellulitis

*life-threatening orbital infection

Front 3

Which wall (lateral or medial) of the orbit, extends farther anteriorly?

Back 3

medial wall

*surgical approach can be made by lateral wall

Front 4

The (lateral or medial) wall is the thickest & strongest, and also most exposed to direct trauma

Back 4

lateral wall

Front 5

Frontal sinusitis has been reported to result in infections of the orbit and abscesses of the frontal lobe of the brain. Where does the frontal sinus extend?

Back 5

extends posteriorly into orbital plate of frontal bone

Front 6

If a sharp object penetrates through the thin bone of the roof of the orbit in a superior direction, what lobe will be punctured?

Back 6

frontal lobe

Front 7

A blow to the eyeball may violently displace the orbital contents inferiorly, fracturing the ___________

Back 7

floor of the orbit

Front 8

Usually the ________prevent the eyeball itself from entering the maxillary sinus, but the inferior rectus muscle may become wedged in a fracture, limiting eye movements

Back 8

infraorbital nerve & vessels

Front 9

Bleeding manifested as a nosebleed (epistaxis) may occur from a damaged _____________

Back 9

infraorbital artery

Front 10

Why is the floor of the orbit relatively stronger in children than in adults?

Back 10

because the small size of the maxillary sinus

(thus inferior blowout fracture is unlikely)

Front 11

The optic canal is closely related to the ________ & _________ & the optic nerve may become infected or damage by surgery on these structures

Back 11

sphenoid sinus and posterior ethmoidal air cells

Front 12

A vein connecting the pterygoid venous plexus of the infratemporal fossa & the inferior ophthalmic vein traverses the ___________ fissure

(providing indirect route for the spread of infection into cranial cavity)

Back 12

inferior orbital fissure

Front 13

The orbital septum separates what spaces?

Back 13

preseptal (periorbital) & postseptal (orbital) space

Front 14

Which is more serious
preseptal cellulitis or orbital cellulitis?

Back 14

orbital cellulitis, more likely to spread into orbit

Front 15

The lens loses elasticity as we age and may remain too flattened to allow a good focus of the image on the retina for (near/far) objects.

Back 15

near objects

*The inability to see near objects clearly with age is presbyopia.

Front 16

Increased intraocular pressure due to decreased _______________ compresses the retina and retinal arteries and may result in blindness.

Back 16

decreased absorption of aqueous humor (glaucoma)

Front 17

Compression of retina & retinal arteries results in gradual visual loss, initially from where?

Back 17

periphery of visual field

Front 18

Describe what will happen if the occulomotor nerve is compressed

Back 18

the parasympathetic fibers, which are located peripherally in the nerve, are affected first and the
pupil dilates (mydriasis) due to paralysis of the sphincter pupillae muscle

Front 19

What may lead to pupil constriction (miosis)?

Back 19

when the sympathetic innervation to the eye is interrupted, as in Horner’s syndrome,

Front 20

The optic retina is formed by an inner light-receptive ________ layer & an outer ___________ layer

Back 20

inner neural layer

outer pigmented layer

Front 21

In a detached retina, the neural and pigmented layers of the optic retina separate, re-creating the _____________ space of the optic cup

Back 21

intraretinal space of the optic cup

Front 22

The inner cells of the neural layer (closest to the vitreous humor) are supplied by what artery?

where does this artery enter the eye?

Back 22

central artery of the retina


optic disc

Front 23

The layers of rods & cones are supplied via diffusion through the pigmented layer from what?

Back 23

vessels of choroid

Front 24

What does a detached retina lead to?

Back 24

loss of photoreceptor cells of the affected area w/ a loss of vision

Front 25

complete ptosis and inability to voluntarily raise the upper eyelid

Horner's or oculomotor lesion?

Back 25

oculomotor lesion

Front 26

partial ptosis while retaining the ability to voluntarily raise the upper eyelid

Horner's or oculomotor lesion?

Back 26

Horner's syndrome

Front 27

____________ muscle depresses the pupil of the already adducted eye, and the ____________ muscle elevates it.

Back 27

Superior oblique muscle

inferior oblique muscle

Front 28

The ___________ muscle elevates the abducted eye, and the _____________muscle depresses it.

Back 28

superior rectus muscle

inferior rectus muscle

Front 29

having the patient look directly to the left requires coordinated contractions of the left __________ muscle and right ____________ muscle.

Back 29

left lateral rectus muscle

right medial rectus muscle

Front 30

If the eye has to be surgically removed, an attempt is made to spare the_________________ & _________________ to form a socket for the artificial eye.

Back 30

fascial sheath and suspensory ligament

Front 31

Due to the extension of the subarachnoid space around the optic nerve, an increase in intracranial pressure reduces ____________________& inhibits ______________to produce swelling of the optic disc (papilledema).

Back 31

reduces venous return from the retina &
inhibits axoplasmic transport

*papilledema= contraindication for lumbar puncture---> brain herniation

Front 32

Swollen optic disc is often the first sign of __________

Back 32

increased intracranial pressure

Front 33

The sensory fibers supplied to the eye by the _________ nerve are tested in the corneal reflex.

The examiner touches the cornea with a wisp of cotton, resulting in reflex closure of the eyelids.

Back 33

nasociliary nerve

Front 34

The afferent limb of the corneal reflex arc, is by cranial nerve ______ & the efferent limb is by
________, which supplies the orbicularis oculi muscle.

Back 34

V1

the facial nerve (VII)

Front 35

Occlusion of the _________ artery by a thrombus results in instant and usually permanent blindness in the affected eye.

Back 35

central artery of the retina

Front 36

Temporary occlusion of the central artery of the retina is one cause of temporary blindness lasting from seconds to hours and known as _____________

Back 36

amaurosis fugax

Front 37

The dorsal nasal artery often anastomoses with the ____________ artery, providing collateral circulation between the internal and external carotid arteries

Back 37

angular artery

Front 38

The ___________ ophthalmic vein drains into the
cavernous sinus, providing a route for the spread of infection from the middle third of the face (danger area) to the cavernous sinus

Back 38

superior opthalamic vein

Front 39

The inferior ophthalmic vein communicates through the ______________ with the pterygoid plexus of veins

(also route for infection to enter cavernous sinus)

Back 39

inferior orbital fissure

Front 40

The inferior ophthalmic vein often drains into the _____________ vein before that larger vein leaves the orbit; however, sometimes the inferior ophthalmic vein drains directly into the cavernous sinus

Back 40

superior ophthalmic vein

Front 41

Occlusion of the _______________ often results in slow, painless visual loss

Back 41

central vein of the retina