Download MBBS Olfactory Nerve Lecture PPT

Introduction

? Almost all environmental chemicals necessary for life enter the body by nose and

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mouth.

? The senses of smell (olfaction) and taste (gustation) monitor such chemicals
determine the flavor and palatability of foods and beverages and
warn of dangerous environmental conditions, including fire, air pollution,

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leaking natural gas and bacteria-Iaden foodstuffs.

? These senses contribute significantly to quality of life and when dysfunctional can

have untoward physical and psychological consequences.

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? A basic understanding of these senses in health and disease is critical for the

physician because thousands of patients present to doctors' offices each year

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with complaints of chemosensory dysfunction.

? Among the more important recent developments in neurology is the discovery that

decreased smell function is among the first signs if not the first sign of such

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neurodegenerative diseases as Parkinson's disease (PD) and Alzheimer's disease

(AD) signifying their "presymptomatic" phase
Olfactory nerve

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? C N I

? Components - sensory ( SVA )

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? Function - olfaction ( smell )

? Opening in skull through which it passes - cribriform plate of ethmoid

bone

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The basic pathways for processing olfactory information.

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Anatomy of the olfactory neural pathways showing the distribution of olfactory

receptors in the roof of the nasal cavity (Copyright Oavid Klemm, Faculty and

Curriculum Support [FACS] Georgetown University Medical Center )

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Structure of olfactory epithelium

(ORNs ? olfactory receptor neurons )

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Peripheral and central components of the primary olfactory pathway

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Schematic representation

of olfactory bulb .

Each receptor type (red

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green,blue) projects to a

common glomerulus.

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The neural activity within

each glomerulus is modul-

ated by peri glomerular

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cells.

The activity of the primary

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projection cells,the mitral

and tufted cells, is

modulated by granule cells

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,periglomerular ceIls, and

secondary dendrites from

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adjacent mitral and

tufted cells

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Central components and basic connections of the olfactory system.


The basic pathways for processing olfactory information.

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