Eye Flashcards
You are testing the extraocular muscles and their innervation in a patient who periodically experiences double vision. When you ask him to turn his right eye inward toward his nose and look downward he is able to look inward, but not down. Which nerve is most likely involved?
Trochlear
In this case, the patient has the eye turned inward, so the doctor must be testing the oblique muscles. The superior oblique muscle is the muscle that lowers the eye when it is turned inward. Since the patient can’t do this, the superior oblique must not be functioning, and this muscle is innervated by the trochlear nerve.
The outermost layer of the optic nerve sheath is a continuation of the:
Arachnoid membrane
Meningeal dura
Periosteal dura
Pia mater
Retina
meningeal dura
The optic nerve comes off the base of the brain and passes through the optic canal. As it leaves the brain, it still retains all of the meningeal layer coverings. So, it is covered by meningeal dura, arachnoid membrane, and pia mater. This is significant, because an increase in intracranial pressure will increase the pressure in the subarachnoid space. This may squeeze the optic nerve and make the optic nerve bulge into the eye, a condition known as papilledema.
The inner lining of the eyelid is called the:
Orbital septum
Palpebral conjunctiva
Periorbita
Sclera
Tarsal plate
palpebral conjunctiva
The palpebral conjunctiva is the thin membrane that lines the eyelid. It is continuous with the bulbar conjunctiva which lines the eyeball.
What would the examining physician notice in the eye of a person who has taken a sympathetic blocking agent?
- Exophthalmos and dilated iris
- Enophthalmos and dry eye
- Dry eye and inability to accommodate for reading
- Wide open eyelids and loss of depth perception
- Ptosis and miosis (pin-point pupil)
Ptosis and miosis (pin-point iris)
Start this question out by thinking about what a sympathetic blocker would do to the pupil of the eye. Since sympathetic nerves allow the pupil to dilate, a sympathetic blocker would stop the eye from dilating and make the pupil constrict. Now think about the other issues. First, remember that sympathetic nerves innervate the superior tarsal muscle, which elevates the eyelids. If there is a problem with the regional sympathetics (as is the case with Horner’s syndrome), the superior tarsal muscle will be paralyzed, and the eyelid will droop (ptosis). If the sympathetic nervous system is inhibited, sweating will cease, and you will observe the eye sinking back into the orbit.
You are examining a patient who has a pituitary tumor involving the cavernous sinus. While doing a preliminary eye exam, you suspect the right abducens nerve of the patient has been damaged by the tumor. In which direction would you have the patient turn his right eye to confirm the defect?
Inward
Outward
Downward
Down and out
Down and in
Upward
Up and out
Up and in
Outward
To understand this question, you need to understand how the motions of the eye are tested. Since the actions of the extraocular muscles are complex, it is necessary to turn the eye to a position where a single action of each muscle predominates when evaluating the individual muscles.
You have a patient with a drooping right eyelid. You suspect Horner’s syndrome. Which of the following signs on the right side would confirm this diagnosis?
Constricted pupil
Dry eye (lack of tears)
Exophthalmos
Pale, blanched face
Sweaty face
constricted pupil
Horner’s syndrome is a disorder involving damage to the sympathetic trunk in the neck. This means that the sympathetics of the head will be disrupted. This causes a variety of very characteristic symptoms, including a constricted pupil. Remember–sympathetic nerves innervate the dilator pupillae muscle. This muscle allows the eye to dilate. If these sympathetic nerves are lost, the pupil will contract.
Following endarterectomy on the right common carotid, a patient is found to be blind in the right eye. It appears that a small thrombus embolized during surgery and lodged in the artery supplying the optic nerve. What artery would be blocked?
Central artery of the retina
Infraorbital
Lacrimal
Nasociliary
Supraorbital
Central artery of the retina
The central artery of the retina is a branch of the ophthalmic artery. It is the sole blood supply to the retina; it has no significant collateral circulation and blockage of this vessel leads to blindness.
You are asked to check the integrity of the trochlear nerve in the right eye of a patient. Starting with the eyes directed straight ahead, you would have the patient look:
Inward, toward the nose and downward
Inward, toward the nose and upward
Toward the nose in a horizontal plane
Laterally in a horizontal plane
Outward, away from the nose and downward
Outward, away from the nose and upward
Inward, toward the nose and downward
To understand this question, you need to understand how the motions of the eye are tested. Since the actions of the extraocular muscles are complex, it is necessary to turn the eye to a position where a single action of each muscle predominates when evaluating the individual muscles.
The ducts of the lacrimal gland open into the:
Superior fornix of the conjunctiva
Inferior fornix of the conjunctiva
Lacrimal puncta
Lacrimal canaliculi
Lacrimal lake
Superior fornix of the conjunctiva
Lacrimal fluid is produced by the lacrimal gland, which lies in a fossa in the superolateral part of each orbit. The fluid from this gland enters the conjunctival sac through up to 12 lacrimal ducts that open into the superior conjunctival fornix. The tears then flow to the medial angle of the eye and collect in the lacrimal lake.
Starting from a position gazing straight ahead, to direct the gaze downward, the inferior rectus muscle must be active along with the:
Superior oblique
Inferior oblique
Medial rectus
Lateral rectus
Superior rectus
Superior Oblique
The inferior rectus muscle depresses the eye and medially rotates it. So, to direct the gaze downward, you want to find a muscle that will depress the eye while counterbalancing the medial rotation with lateral rotation.
During a physical examination it is noted that a patient has ptosis. What muscle must be paralyzed?
Orbicularis oculi, lacrimal part
Orbicularis oculi, palpebral part
Stapedius
Superior oblique
Superior tarsal (smooth muscle portion of levator palpebrae)
Superior tarsal
The superior tarsal muscle is a smooth muscle which is sympathetically innervated. It is an involuntary muscle that elevates the eyelid.
The extraocular muscle that does not originate at or near the apex of the orbit is the:
Inferior oblique
Inferior rectus
Levator palpebrae superioris
Superior oblique
Superior rectus
Inferior oblique
The inferior oblique muscle does not originate at the apex of the orbit. It takes origin from the floor of the orbit, lateral to the lacrimal groove.
An adolescent boy suffers from severe acne. As is often the case he frequently squeezed the pimples on his face. He subsequently develops a fever and deteriorates into a confused mental state and drowsiness. He is taken to his physician and after several tests a diagnosis of cavernous sinus infection and thrombosis is made. The route of entry to the cavernous sinus from the face was most likely the:
Carotid artery
Mastoid emissary vein
Middle meningeal artery
Ophthalmic vein
Parietal emissary vein
Ophthalmic vein
The ophthalmic veins are continuous with the facial vein and the pterygoid plexus of veins. These veins drain the face toward the cavernous sinus. They are valveless, so infections from the face can drain into the cavernous sinus.
If a person looking inward towards their nose is unable to look down, which nerve may be injured?
Abducens (CN VI)
Inferior division of oculomotor (III)
Optic (II)
Superior division of oculomotor (III)
Trochlear (IV)
Trochlear (IV)
If a person is taking a sympathetic blocking agent, what would you notice in her or his eyes?
Dry eyes and inability to accommodate for reading
Enophthalmos and teary eyes (III)
Exophthalmos and dilated pupil
Ptosis and constricted pupil
Wide open eyes and loss of depth perception (IV)
Ptosis and constricted pupil
To understand this question, it’s important to look at all the different choices and determine which ones fit with a sympathetic block. First, the lacrimal gland is innervated parasympathetically, so a sympathetic blocker should have no effect on eye secretions. Accomodation is also a function of the parasympathetic nervous system; it should not be altered by a sympathetic blocker.
