Visual Pathways: Ophthalmology textbook AK khurana comprehensive ophthalmology .pptx

Visual Pathways: Ophthalmology textbook AK khurana comprehensive ophthalmology

1. blue sclera? 326 Section next page

2. 328

3. Light reflex: Bilateral pupil constriction In response to light Accommodation convergence reflex (no pretectal needed): Bilateral pupil constriction in the near response + Edinger-Westphal

4. 1. Optic nerve 4. Ciliary ganglion 3. CN III 2. Pretectal 329

5. Epidural Hematoma; CN III and CST Compression

6. Back to 326 Section next page

7. Visual Processing Neuron #1 Neuron #2 330

8. Notes Like a camera, the lens inverts image of visual field Nasal retina receives information from temporal visual field Temporal retina receives information from nasal visual field At optic chiasm, optic nerve fibers from nasal half of each retina cross and project to contralateral optic tract Parietal Lobe Temporal Lobe Occipital (visual cortex) 331 Left side

9. 1. Lesions in front of chiasm: Deficits are monocular and ipsilateral (1,2) Left side

10. at the chiasm: Deficits are binocular, bitemporal, and heteronymous (3)* Left side

11. 3. Past the chiasm: deficits are binocular, contralateral and homonymous (4.5.6) Light reflex suppressed in lesion At 4, intact at 5,6 Left side

12. Lesions inside visual cortex result in macular sparing deficits (7). Special lesions past the chiasm and LGN Left side

13. The visual radiations project to the primary visual cortex Half of the visual radiations (green) convey information from the lower quadrants of the visual hemifields and project through the parietal lobe to the cuneus, the primary visual cortex superior to the calcarine sulcus. The other half of the visual radiations (red) convey information from the upper quadrants of the visual hemifields and project to the lingual gyrus, inferior to the calcarine sulcus. This half of the visual radiations forms Meyer’s loop (red). The fibers of Meyer’s loop make a hairpin turn in the temporal lobe before coursing posteriorly to reach the lingual gyrus. The central parts of each visual field representing the area of the macula (fovea) are in the posterior part of primary visual cortex near the tips of the occipital lobes (black). Macular cortex has dual blood supply

14. 341

15. 346

16. Primary Somatosensory cortex Primary motor cortex Head, Neck Upper limb, 342

17. Primary motor cortex Bladder and Lower limb Primary Somatosensory cortex 342

18. Global ischemia affects: Hippocampus Purkinje cells Watershed areas 343

19. 346

20. 347 343 Watershed areas

21. L hemisphere Dominant for Language 95% of Right handers 70% of Left handers Prosodic centers: Emotional content of speech Speaks in a monotome Doesn ’ t understand emotional content Language comprehension Motor speech 347

22. Visual 347

23. Right upper limb and Lower face weakness Right upper limb and facial anesthesia Motor Speech oral comprehension Written comp. 349

24. 358 Unaware of deficit

25. Individuals with a lesion to the inferior parietal lobule (supramarginal gyrus; area 40 ) may have an ideomotor apraxia , in which they cannot perform tasks on command even though there is no motor weakness. In Gerstmann’s syndrome, these patients also have agraphia, acalculia (an inability to perform simple arithmetic problems), finger agnosia (an inability to recognize one’s fingers), and right–left disorientation. A lesion that includes the angular gyrus in the left inferior parietal lobule (39) may also result in a loss of ability to comprehend written language (alexia) and to write it (agraphia), but spoken language may be understood.

26. Right Parietal lobe Lesion only

27. 355

28. Internal Capsule Lesions: A lacunar stroke involving the genu of the internal capsule (c) may result in contralateral lower face weakness due to a lesion of the corticobulbar axons A lacunar stroke involving the posterior limb of the internal capsule (d) may result in a complete contralateral anesthesia, and a contralateral spastic hemiplegia, Thalamus lesion (a): A lacunar stroke of the thalamogeniculate arteries to the thalamus result is a complete contralateral face limbs and body sensory loss Head of caudate nucleus (b): site of neuronal loss in Huntington’s disease Anterior cerebral and medial striate arteries Middle Cerebral Lenticulostriatearteries

29. Hippocampus Amygdala 359 360

30. U III 361

31. 362 Mammillary body degeneration in Korsakoffs syndrome

32. Sites of degeneration In Alzheimer ’ s disease Basal nucleus of Meynert Cholinergic projection Enhances consolidation

33. 363 What letter marks lesion site in one With chewing weakness and facial numbness? One with vertical gaze weakness, increased ICP and Arygl Robertson pupils?

34. a b c d Patient has occlusion of Vessel at “ a ” . Sign or symptom? A. Altered facial sensation B. Difficulty arising from a chair C. Receptive aphasia D. Suppressed triceps reflex E. Lower face weakness From Road Map Neuroscience 2nd edition 2008

35. A patient is capable of displaying bilateral pupillary constriction during an accommodation reaction but not in response to a direct-light stimulus. Which of the following is the most likely site of the lesion?   A Optic nerve  B Lateral geniculate nucleus  C Pretectal area  D Visual cortex  E Edinger-Westphal nucleus

36. Where is the lesion site that causes this visual field deficit? Bottom of optic chiasm Right Meyers loop Left cuneus gyrus Left Optic tract E. Right lingual gyrus

37. A 74-year-old man is unable to repeat phrases and name objects after having a left-sided stroke. Although reading comprehension is preserved, he has difficulty reading aloud and writing. His speech is fluent, and his comprehension is normal. Which of the following structures is most likely damaged?   A) Arcuate fasciculus B) Left frontal cortex C) Left temporal lobe D) Corpus callosum E) Angular gyrus

38. A 51 year old male undergoes an anterolateral cordotomy to relieve the pain of metastatic intraabdominal cancer. This procedure is most likely to result in degeneration of pain carrying axons. I n which of the following labeled structures do pain carrying axons terminate in the MRI of the normal head?

39. E D C B A Which letter marks the location in the retina where phototransduction occurs?

40. A 55 year-old male suffers a vascular hemorrhage of the left temporal retina. Where will there be decreased visual processing? A. Optic chiasm B. Left lateral geniculate nucleus C. Right Meyer’s loop D. Right Cuneus gyrus E. Left medial geniculate nucleus

41. Patient has lesion in hatched area. What will be an expected finding? Lower face weakness B. Ipsilateral hearing loss C. Gerstmann syndrome D. Unilateral neglect E. Fluent aphasia