Ocular anatomy

Sympathetic innervation to the dilator follows the course of which of the following sensory nerves?
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Terms in this set (29)
Macula.
in order of strongest to weakest:
1. Ora Serrata
2. Posterior Lens
3. Optic Nerve
4. Macula
5. Retinal Vessels
Recall that the vitreous has the highest amount of collagen in areas of the tightest attachments - so
the vitreous base, where the ora serata is located, would have the highest amount of collagen -
that is why it is the tightest attachment. The central vitreous has the lowest amount of collagen
What is not true regarding neuroglial cells? A. Involved in glycogen metabolism -- provide nutrients to retina. B. Involved in immunological activities -- some are phagocytic cells C. Provide structure, support, and protection D. Contribute to signal processing when necessaryD. No role in signal processing -- everWhich region of the macula has the thickest region of ganglion/bipolar cells? A.Parafovea B.Perifovea C.FoveaA. Remember, this is because the foveala is void of bipolar and ganglion cells. During development, these cells are pushed to the side, contributing to the thickness of the parafovea - this is the thickest area of the entire retina.Where is the thickest region of rods in the retina? A. Parafovea B. 6 mm from the center of the foveala C. Foveala D. Just outside the perifoveaD. You have heard many times that there are no rods in the fovea. To be more specific, remind yourself... there are no rods until JUST OUTSIDE THE PERIFOVEA(the outer region of the fovea) - this is called the rod ring, and it is located 5 mm outside the foveala.Which of the following fibers would be medial in the left optic tract? A. Ipsilateral inferior temporal & contralateral inferior nasal. B. Ipsilateral superior temporal & contralateral superior nasal.Superior fibers - always go MEDIAL. Inferior fibers -- always go LATERAL. I know this is confusing to some of you. All of you know that nasal fibers cross - the only additional thing you need to remember is that the superior nasal fibers cross and go medial (into parietal lobe) - while the inferior nasal fibers cross and go lateral (into temporal lobe). The temporal fibers never cross. The superior temporal fibers stay ipsilateral, but course medial (into parietal lobe). The inferior temporal fibers stay ipsilateral, but course lateral (into the temporal lobe).Stimulation of sympathetic receptors cause A. Increase in IOP B. Decrease in IOP C. Both D. NeitherC. Both - it depends on which receptors are acted upon. A2 -- stimulation constricts blood vessels in the major arterial circle of the iris and decreases IOP. This is how apraclonidine and brimonidine (the alpha 2 agonists) decrease IOP. B1 and B2 -- stimulation increases aqueous humor production. B-blockers block these receptors, decreasing IOP.The majority of blood within the eye is found within the: A. Central retinal artery B. Long and short posterior ciliary arteries C. Conjunctiva D. Ciliary body vasculatureB. Long and short posterior ciliary arteries Recall that the choroid has the majority of blood flow. Two blood vessels combine to provide the choroidal flow - each artery does two main things: --LPCA: does anterior choroid, and contributes to majorarterial circle of the iris. --SPCA: does posterior choroid, and forms the Circle of Zinn (provides for surface of the optic disc). EXTRA CREDIT.... Even though the majority of blood flow is within the choroid, the majority of oxygen in the eye is within the RETINAL arteries.The infraorbital nerve is a branch of which of the following? 1. V1 2. V2 3. VII 4. VIIIV2 - Recall that V1 courses above the eye and has three branches - Nasociliary, Frontal, Lacrimal (NFL). Recall that the frontal nerve branches into the supraorbital and supratrochlear nerves. V2courses below the eye and has two branches - Infraorbital and Zygomatic - 1. V1 = Above the Eye = NFL. Think of the F as the Forehead because the Frontal Nerve divides into two nerves that supply the forehead region. 2. V2 = Below the Eye. Just like the supraorbital nerve supplies above the eye, the infraorbital nerve supplies below the eye. Thus, it should be logical to you that the supraorbital nerve is part of V1 and the infraorbital nerve is part of V2.Which visual field defect(s) is/are NOT caused by a post-chiasmal lesion? a) junctional scotoma b) lesion respecting the vertical midline in the left eye c) pie on the floor (quadrantopsia) defect which is incongruous d) macula only (involving) homonymous hemianopsiaA and B A is caused by a chiasmal lesion which has pushed forward and compresses on the entire nerve of one eye and the nasal fibers (part of the anterior knee of Wildebrand) of the other. B Post-chiasmal lesions are always bilateral.Which statements are true regarding Fuch's heterochromic iridocyclitis? a) The endothelium has guttata and the cornea can become edematous. b) The patient will be asymptomatic to the uveitis (will not have symptoms typical of a uveitis such as photophobia, pain, etc.) c) Granulomatous KP's are present d) This represents a chronic uveitisb and d Don't get confused between Fuch's endothelial dystrophysame last name but a completely different condition! The patient may become symptomatic with blur due to the cataract but not from this chronic form of uveitis. The keratic precipitates will be non-granulomatous.A lesion at the pons would case an ipsilateral or contralateral loss of voluntary movements?Contralateral This is the pyramidal motor pathway which carries fibers for voluntary movements. It decussates (crosses the midline) at the pyramids (in the upper medulla) which is inferior to the lesion, therefore, the affect would be on the contrlateral side.A lesion at the midbrain would affect the ipsilateral or contralateral touch/pressure/vibration information?Contralateral The Medial Lemniscus pathway carries the fibers for touch/pressure/vibration and it decussates at the medulla. This decussation is inferior to the lesion, therefore, the contralateral side of the body would be affected because it's corresponding fibers would be affected.T/F: The temporal lobe carries inferior fibers of Meyer's LoopT Therefore, a lesion of the temporal lobe causes a pie-in-the-sky defect (PITS VF defect)T/F: Papillitis refers to disc edema caused by optic neuritis which affects the anterior 1/3 of the optic nerve.T If the optic neuritis occurs in the posterior 2/3, it is called retrobulbar optic neuritis and the optic nerve will appear normal.A carotid dissection is a potential cause of Horner's syndrome. What type of lesion does this represent? a) central b) post-ganglionic c) pre-ganglionicb After the superior cervical ganglion, this part of sympathetic innerviation to the eye is considered the postganglionic part of the nerve. At this point, it runs for a short time with the carotid artery. Therefore, carotid dissection can cause a lesion in the post-ganglionic part of the nerve. fyi- A carotid dissection occurs when the inner lining of the artery pulls away and fills with blood. This causes a narrowing of the lumen and there is risk for stroke. The patient will likely have h/o trauma and/or sudden pain to the head and neck.What is the mechanism behind steroid-related increases in IOP (steroid response)? What percent of the general population are steroid responders? What percent of POAG patients are steroid responders?Steroid responses occur as a result of decreased outflow through the TM. Bartlett and Janus' textbook overview various mechanisms include a thickening of trabecular fibrils and juxtacanalicular tissue and a decreased ability for the TM to replace matrix and phagocytose debris. Main point = outflow is decreased through the TM! - Correct Answer = 5% of the general population are steroid responders. 90% of POAG patients are high steroid responders.An orbital infection that involves the lamina papyracea can cause what dreaded ocular infection?Orbital Cellulitis This question combines knowledge of several different concepts. Recall that the lamina papyracea is another name for the ethmoid bone. Recall that an ethmoid sinusitis (SINUS INFECTION) is the most common cause of orbital cellulitis. An orbital cellulitis is very dangerous because it can spread posteriorly and result in meningitis.What anatomical changes occur as you go from the cornea to the limbus?Correct Answer = Two structures END and two structures BEGIN! 1. END = Bowman's layer and Descemet's layer. Recall that Descemet's layer becomes Schwalbe's Line. 2. BEGIN = Conjunctiva and Tenon's capsuleWhich of the following provide blood supply to the eyelids? (Pick 3) 1. External carotid through facial artery branches 2. Short posterior ciliary arteries (SPCA's) 3. Muscular arteries 4. Ethmoid arteries 5. Branches of the ophthalmic artery 6. Medial and lateral palpebral arteriesCorrect Answers = 1, 5,6 The two main arteries that supply the eyelid are: 1) Internal carotid = "internal" portion of the eyelid. Utilizes branches of the ophthalmic artery (medial and lateral palpebral arteries) 2) External carotid = "external" portion of the eyelid. Utilizes branches of the facial artery. MEDIAL and LATERAL PALPEBRAL ARTERIES = OPHTHALMIC ARTERY BRANCHESWhere does Tenon's capsule begin in relation to the limbus? Perforation of Tenon's capsule in the posterior pole allows for passage of what important structures? Which of the following are posterior to TENON'S CAPSULE? (Pick 2) 1. Conjunctival epithelium 2. Conjunctival stroma 3. Sclera 4. EpiscleraCorrect Answer = Tenon's capsule begins 2 mm posterior to the limbus. Correct Answer = Basically the optic nerve and a bunch of valuable arteries, veins, and nerves. I wouldn't get too picky here, but here they are: Vortex veins, Posterior ciliary arteries, veins, and nerves (e.g. SPCA's, LPCA's, etc) Correct Answers = 3, 4 Summary: Picture looking at the limbus under the slit lamp. Just 2 mm posterior to the limbus Tenon's capsule starts by FUSING WITH THE BACK SIDE OF THE CONJUNCTIVA. That is a key sentence to remember. If you know it is just barely posterior to the conjunctiva, it should be fairly obvious that the conjunctival epithelium and conjunctival stroma are anterior to this structure and the episclera and sclera are posterior, respectively. As Tenon's reaches the posterior pole, it has pores that allow for the axons of ganglion cells (optic nerve) to enter the eye.