Basic Ocular Anatomy Cards Flashcards
What are the two types of sinuses within the cranium?
Sinuses within the head can be filled with either air or blood. (paranasal sinuses around the globes = air; cavernous sinus = venous blood)
A lesion in the superior division of CN III would result in which of the following?
- An eye that sits down and out.
- Ptosis
- Loss of accommodation
Answer: 2; ptosis
Remember that the superior division of CN III innervates superior things: superior levator muscle (opens the eye) and the superior rectus (elevates the eye).
What condition results from a lesion at the location of the ciliary ganglion?
Answer: ADie’s tonic pupil. (Acute, Dilated)
Recall: 0.125% pilocarpine is used for diagnosis. The ciliary ganglion is utilized for the light responses AND the near responses, so patients with Adie’s tonic pupil will have a delayed light and near response.
Which of the following nerves is used for shoulder shrugging?
- X
- XI
- XII
- IX
Answer: 2, XI; student nerve = head turning and shoulder shrugging
Think of CN XI as the “student nerve.” Sometimes when I ask my students questions they will shrug their shoulders and turn their head from side to side (horizontally) to express their lack of knowledge of the topic (or disdain of my question).
The optic nerve courses to all of the following destinations except:
- Superior colliculus
- Inferior colliculus
- LGN (and onto the visual cortex)
- Pretectal nucleus
Answer: Inferior colliculus
Recall: the optic nerve, just prior to entering the LGN, gives off 1/3 of its fibers to the pretectal nucleus. The fibers leaves the pretectal nucleus to innervate both Edinger-Westphal nucleus.
Where do preganglionic parasympathetic fibers that course to the pupil originate at the eye?
- Superior colliculus
- Inferior colliculus
- LGN (and onto the visual cortex)
- Pretectal nucleus
- Edinger-Westphal nucleus
Answer: EW nucleus; don’t put pretectal nucleus if asked on exam!!!
Where do postganglionic parasympathetic fibers that course to the pupil originate at in the eye?
- Inferior colliculus
- LGN
- EW nucleus
- pretectal nucleus
- ciliary ganglion
Answer: ciliary ganglion
Remember, when you are checking pupils in clinic, CN 2 (optic nerve) performs the sensory loop, while CN 3 (belonging to EW nucleus) performs the motor loop. The fibers that course from the pretectal nucleus to both EW nuclei are known as interneuron loop or the tectotegmental tract
Which of the following bones does not contribute to the medial wall of the orbit? A. body of the sphenoid B. maxilla C. lacrimal bone D. greater wing of the sphenoid
Answer: D, greater wing of sphenoid
The bones of the medial wall include ELMS (ethmoid, lacrimal, maxilla, sphenoid; or SMEL). Do not confuse the maxillary bone with the maxilla bone. The maxillary bone makes up the majority of the floor. The maxillary sinus liens under the maxillary bone.
Which of the following is correct?
A. Upon adduction 23º the superior rectus is the primary elevator.
B. Upon abduction 51º the inferior oblique is the primary elevator.
C. Upon abduction 23º the inferior rectus is the primary depressor
Answer: C, upon ABduction 23º the inferior rectus is the primary depressor.
Which of the following muscles causes intorsion, ABduction, and depression? A. superior oblique B. superior rectus C. inferior rectus D. inferior oblique
Answer: A, superior oblique.
The primary actions of the superior oblique and inferior oblique are intorsion and extorsion.
When are the oblique muscles responsible for elevation and depression?
When the eye is pointed towards the nose (ADducted 51-55º).
Recall that the recti muscles are isolated for elevation and depression when ABducting 23º.
Clinically, when a patient is instructed to look straight up, which muscle(s) is/are performing this action?
Superior rectus and inferior oblique
Where does the inferior oblique muscle start its course?
Maxillary bone
What two bones comprise the lateral wall of the orbit? A. greater wing of the sphenoid B. lesser wing of the sphenoid C. frontal bone D. zygomatic bone
Answer: A and D, greater wing of sphenoid and zygomatic bone.
Some remember the two bones that comprise the lateral wall as “great-Z.”
The bulbar conjunctiva and the ciliary body both receive part of their blood supply from which of the following? A. short posterior ciliary arteries B. supraorbital arteries C. anterior ciliary artery D. supratrochlear artery
Answer: C, anterior ciliary artery.
- The major arterial circle of the iris (MACI) is comprised of the long posterior ciliary arteries and the anterior ciliary arteries. Recall that MACI is actually located in the ciliary body and provides blood supply to this region.
- The bulbar conjunctiva is also supplied by the anterior ciliary arteries.
Good way to remember: your uveitis patient will have inflammation of ciliary body + circumlimbal injection
Lateral conjunctival lymphatics drain into which of the following?
A. submandibular lymph nodes
B. Preauricular lymph nodes
C. Axilla lymph nodes
Answer: B, preauricular lymph nodes
- Lateral lymphatics drain into the preauricular (parotid) lymph nodes.
- Medial lymphatics drain into the submandibular lymph nodes.
Which of the following glands are responsible for lubricating the eyelashes?
A. Zeis
B. Moll
C. Krause
Answer: A, Zeis
Zeis glands have a secondary function of assisting the glands of Moll and meibomian glands in the production of the lipid layer of the tear film.
Which layer of the tear film is secreted by blinking?
The lipid layer.
Where are each of the following muscles located and what are their functions?
A. frontalis
B. procerus
C. corrugator
Frontalis: runs in a vertical orientation from the forehead down to each eyelid. Functions to raise the eyebrow for a look of surprise.
Procerus: located between the eyes on the bridge of the nose. Pulls skin between the eyelids downward for an appearance of menace or aggression.
Corrugator: small, narrow muscle located on the medial edge of the eyebrow. It’s right above the orbicularis oculi (right at the level of the eyebrow), along the medial edge. Think of the CORrugator = CORner of the upper eyebrow. It moves the eyebrown down and medial and is sometimes referred to as the “frowning muscle.” It also is used for a look of concentration.
Which of the following layers of the eyelid contains goblet cells? A. subcutaneous areolar layer B. outer skin layer C. tarsal plate D. palpebral conjunctiva
Answer: D, palpebral conjunctiva. This layer is also very immunologically active – has IgA antibodies.
Think of the anterior portion of the eyelid as being comprised of skin and orbicularis oculi muscles – the middle of the eyelid as the orbital septum – and the posterior portion of the eyelid as the levator and tarsal plate.
Which of the following pupil abnormalities would be most prevalent in the light?
A. Adie’s tonic pupil
B. Horner’s syndrome
C. Argyll Robertson Pupil
Answer: A, ADie’s tonic pupil.
Acute Dilated pupil; therefore, in the light (where you would anticipate constriction) the pupil will stay dilated. Horner’s, a miotic pupil, would be most obvious in the dark.
Sympathetic innervation to the dilator follows the course of which of the following sensory nerves?
A. facial nerve
B. nasociliary nerve
C. zygomatic nerve
Answer: B, nasociliary nerve.
When the sympathetic nervous system climbs up into the brain, it has two main options: dilator muscle (through nasociliary route) or Muller’s muscle (remember Muller’s MAINTAINS the eye being open). When you hear sympathetic innervation, you should instantly think: dilator muscle and Muller’s muscle.
Which of the following would not result from a pancoast tumor?
a. ptosis
b. miosis
c. exophthalmos
d. anydrosis
e. reverse ptosis
f. dilation lag
Answer: c, exophthalmos
Pancoast tumor affects (preganglionic) sympathetic fibers, just like Horner’s. We can anticipate the effects of miosis, ptosis, reverse ptosis, anhydrosis and dilation lag.
The Pancoast tumor arises at the apex of the lung, so preganglionic sympathetic fibers would be affected with this condition. Sympathetic fibers become postganglionic after synapsing in the superior cervical ganglion.
Which of the following statements is true?
a. Strokes are supranuclear lesions that result in ipsilateral muscle paralysis
b. Bell’s palsy is a lower motor neuron lesion that results in contralateral muscle paralysis to the entire side of the face.
c. Strokes are lower motor neuron lesions that result in contralateral paralysis.
d. Bell’s palsy is a lower motor neuron lesion that results in ipsilateral damage to the entire side of the face.
Answer: D
Remember that strokes cause contralateral issues. Bell’s is the opposite; because it damages lower motor neurons (neurons that have already crossed the brainstem) and results in ipsilateral issues.
Our main concern with Bell’s palsy is exposure keratopathy because Bell’s is an idiopathic CN VII palsy. And CN VII closes the eye. With the lack of CN VII innervation, you can result in ectropion and subsequent corneal exposure.
