Notes on Visual Pathways

  >   Rahul's Noteblog   >   Notes on Neurology   >   Notes on Visual Pathways

Mechanism of Vision:

• Photopigments in rods and cones absorb photons.

• Molecular structure of these pigments altered.

• Na channels close.

• Hyperpolarization.

• Less neurotransmitter released.

• Rods and cones release less neurotransmitter in light, and more neurotransmitter in dark.

• Rods and cones are connected to bipolar cells that are connected to ganglion cells.

Accommodation Reflex:

• Ciliary muscle contracted.

• Pupillae muscle contracted.

• Convergence.

Lesions in Visual Pathways:

• Optic nerve: blindness and loss of sensory light reflex.

• Optic chiasm compression due to pituitary tumor or meningioma: loss of peripheral vision in both temporal fields, also known as bitemporal heteronymous hemianopia.

Visual Pathway Lesions:

Visual Pathway Lesions

Pupillary Light Reflex:

• Light shone into one eye; impulses carried by optic nerve through to Edinger-Westphal nucleus, then distributed to both eyes.

• Edinger-Westphal nucleus = parasympathetic nucleus of oculomotor nerve.

Accommodation-Convergence Reaction:

• Occurs when the eye focuses on a nearby object after looking at a distant object.

• Involves: ciliary ganglion, preganglionic parasympathetic fibers, Edinger-Westphal nucleus, post-ganglionic parasympathetic fibers, ciliary muscle.

Additional Readings:

Basic Neurology

1. Peripheral Nervous System
2. Central Nervous System
3. The Ventricular System
4. The Spinal Cord
5. The Brain Stem
6. The Cerebellum
7. Visual Pathways
8. Diencephalon
9. Basal Ganglia
10. Cerebral Cortex
11. Sleep Disorders
12. Autonomic Nervous System
13. Cranial Nerves and Parasympathetic Ganglia
14. Cells of the Nervous System
15. Cerebrospinal fluid
16. Additional short notes on Cerebrum
17. Functions and Diseases of Cerebrum
18. Subcortical Grey Matter
19. Notes on The Spinal Cord
20. Regulation of Heart Rate by Autonomic Nervous System
21. Action Potentials, Axon Conduction, and Neuromuscular Junction
22. Types of Seizures
23. What is a Cough Reflex?
24. Notes on Congenital Prosopagnosia
25. Findings in Parkinson's Disease
26. Types of Heat Strokes
27. Types of Strokes
28. What is Benign Intracranial Hypertension?
29. What is Cauda Equina Syndrome?
30. Cranial Nerve Locations in Brain Stem
31. What is a Cluster Headache?
32. What is a Subarachnoid Hemorrhage?
33. What is a Tension Headache?

Neurology Videos

1. Video of Neurology Examination in a Clinical Setting

Medical Images

Useful Medical Images & Diagrams (link opens in a new window)

Related Topics

1. Nervous System Disorders
2. Histology of Nervous Tissue
3. Cranial Nerve Reflexes
4. Motor System Examination

Random Pages:

Why did I become a doctor? My First Computer - Pentium with Windows 95
Video of me playing Hagood Hardy`s "Children of the Dream" Notes on Integument
Notes on Back and Nervous System Notes on Rickettsia
Notes on What is Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCADD)? Notes on Inferential Statistics
Significance of Glycosylated Hemoblogin (HbA1c) Digestion FAQ, Defecation reflex, etc.
Notes on Basic Gastrointestinal Physiology Inferential Statistics
Review of eBoundhost VPS hosting What is an ELEK`s Test?
Why did I decide to become a doctor? Medical School Admissions Essay Video: Titanic Piano Theme: The Portrait
Corporate Failure: The Enron Case My Experience during the Iraqi Invasion of Kuwait
USMLE Blood Lab Values Regulation of Heart Rate by Autonomic Nervous System
Images of Antibodies Rahul`s Piano Music MP3 Collection
Notes on Integument Differentiation and Anatomy of a Blastocyst
Notes on Cell Components Notes on Nervous Tissue
Voices from Hell: My Experience in Mussoorie, India Video of Cardiology Examination in a Clinical Setting

Please Do Not Reproduce This Page

This page is written by Rahul Gladwin. Please do not duplicate the contents of this page in whole or part, in any form, without prior written permission.