Anatomy and Physiology XXVIII

Question 1

What results from retinal detachment?

Answer 1

Degeneration of photoreceptors cause vision loss (p.441)

Question 2

To what causes may retinal detachment be a secondary consequence?

Answer 2

Retina breaks (surgical emergency), diabetic traction, inflammatory effusions (p.441)

Question 3

What types of patients are most prone to retinal breaks?

Answer 3

Patients with high myopia (p.441)

Question 4

What condition typically proceeds retinal breaks?

Answer 4

Posterior vitreous detatchment (flashes and floaters) and eventual monocular loss of vision (p.441)

Question 5

What is the macula?

Answer 5

The central area of the retina (p.441)

Question 6

What symptoms are caused by age related macular degeneration?

Answer 6

Distortion (metamorphopsia) and eventual loss of central vision (scotomas) (p.441)

Question 7

What is dry macular degeneration?

Answer 7

Nonexudative macular degeneration with deposition of yellowish extracellular material beneath retinal pigment epithelium with a gradual decrease in vision (p.441)

Question 8

What is wet macular degeneration?

Answer 8

Exudative macular degeneration with rapid loss of vision due to bleeding secondary to choroidal neovascularization (p.441)

Question 9

Is wet or dry macular degeneration more common?

Answer 9

Dry (nonexudative) > 80% (p.441)

Question 10

How is progression of dry macular degeneration prevented?

Answer 10

Multivitamin and antioxidant supplements (p.441)

Question 11

How is wet macular degeneration treated?

Answer 11

Anti-VEGF injections or laser treatment (p.441)

Question 12

What is anopia?

Answer 12

Complete loss of vision in an eye (p.441)

Question 13

What is hemianopia?

Answer 13

Loss of half of a visual field (p.441)

Question 14

A lesion in what location would cause left upper quadrantic anopia?

Answer 14

In the right Meyer’s loop of the temporal lobe; MCA infarct (p.441)

Question 15

A lesion in what location would cause left lower quadrantic anopia?

Answer 15

In the right dorsal optic radiation of the parietal lobe; MCA infarct (p.441)

Question 16

What is a scotoma?

Answer 16

Loss of central vision (p.441)

Question 17

Where is Meyer’s loop?

Answer 17

The inferior retina; it loops around the inferior horn of the lateral ventricle (p.441)

Question 18

Where is the Dorsal Optic Radiation?

Answer 18

The superior retina; it takes the shortest path via the internal capsule (p.441)

Question 19

In what orientation is an image as it hits the primary visual cortex?

Answer 19

Upside down and left-right reversed (p.441)

Question 20

What is the medial longitudinal fasciculus (MLF)?

Answer 20

A highly myelinated pair of tracts that allows for crosstalk between CN VI and CN III nuclei; it coordinates both eyes to move in the same horizonal direction (p.442)

Question 21

In what types of conditions are lesions to the MLF most common?

Answer 21

Demyelinating conditions (ex. MS) (p.442)

Question 22

What are lesions to the MLF called?

Answer 22

Internuclear opthalmoplegia (INO) (p.442)

Question 23

Describe the clinical findings associated with internuclear opthalmoplegia.

Answer 23

Lack of communication between the eyes such that when CN VI nucleus activates the ispilateral lateral rectus, the contralateral CN III nucleus does not stimulate the medial rectus to fire. Abducting eyes have nystagmus (CN VI overfires to stimulate CN III) but convergence is normal (p.442)

Question 24

Describe the coordination between CN III and CN IV in horizontal gaze.

Answer 24

When looking to the left, CN VI fires, contracting the left lateral rectus and stimulating the contralateral (right) nucleus of CN III via the right MLF to contract the right medial rectus (p.442)