Research Paper Two Olfactory Pathways to Detect Aldehydes ...
OLFACTORY & VESTIBULOCOCHLEAR PATHWAYS
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Transcript of OLFACTORY & VESTIBULOCOCHLEAR PATHWAYS
Dr. Ahmed Fathalla Ibrahim
OLFACTORY PATHWAYOLFACTORY PATHWAY
OLFACTORY PATHWAYOLFACTORY PATHWAY
• Composed of two neuronesComposed of two neurones
• Only sensory pathway that does not Only sensory pathway that does not project via thalamusproject via thalamus
OLFACTORY PATHWAYOLFACTORY PATHWAY
First Order Neurone: First Order Neurone: ciliated nerve ciliated nerve cells in olfactory epithelium of nasal cells in olfactory epithelium of nasal cavitycavity
Axons (olfactory nerve fibers) (olfactory nerve fibers) enter cranial cavity through cribriform plate cribriform plate of ethmoid of ethmoid to reach the olfactory bulbthe olfactory bulb
OLFACTORY PATHWAYOLFACTORY PATHWAYSecond Order Neurone: Second Order Neurone: mitral cells in mitral cells in
olfactory bulbolfactory bulb Axons form the olfactory tract the olfactory tract that
passes backward on inferior surface of on inferior surface of frontal lobefrontal lobe then divides (just before reaching optic chiasma) into 3 stria 3 stria (lateral, intermediate & medial)
Most of fibers run in lateral olfactory lateral olfactory striastria (in depth of lateral fissure) (in depth of lateral fissure) & terminate in Primary Olfactory Cortex Primary Olfactory Cortex (Uncus)(Uncus)
OLFACTORY PATHWAYOLFACTORY PATHWAY
Primary Olfactory cortex is connected to the Olfactory Association Cortex Olfactory Association Cortex (anterior part of parahippocampal (anterior part of parahippocampal gyrus or entorhinal cortex)gyrus or entorhinal cortex)
Both Primary & Association cortex are called Pyriform CortexPyriform Cortex
Cells of Spiral Ganglion (in cochleaCells of Spiral Ganglion (in cochlea))
Dorsal & Ventral Cochlear NucleiDorsal & Ventral Cochlear Nuclei
Trapezoid BodyTrapezoid Body
Lateral LeminiscusLateral Leminiscus Superior Superior Olivary Olivary NucleusNucleus
Nucleus of Nucleus of Lateral Lateral
LeminiscusLeminiscus
Inferior ColliculusInferior Colliculus
Medial Geniculate NucleusMedial Geniculate Nucleus
Primary Auditory CortexPrimary Auditory Cortex
Auditory Association CortexAuditory Association Cortex
Inferior ColliculusInferior Colliculus
Auditory RadiationAuditory RadiationRetrolenticular Part of ICRetrolenticular Part of IC
Dorsal & Ventral Cochlear NucleiDorsal & Ventral Cochlear Nuclei
Cells of Spiral GanglionCells of Spiral Ganglion
Medial Geniculate NucleusMedial Geniculate Nucleus
Primary Auditory CortexPrimary Auditory Cortex
Auditory Association CortexAuditory Association Cortex
Commissural fibersCommissural fibers
Cochlear nerveCochlear nerve Cochlear nerveCochlear nerve
NOTES ON AUDITORY PATHWAYNOTES ON AUDITORY PATHWAY• Cochlear nerve makes dendritic contact with Cochlear nerve makes dendritic contact with
hair cells of hair cells of Organ of Corti Organ of Corti (in Cochlear Duct)(in Cochlear Duct)• Superior Olivary Nucleus & Nucleus of Superior Olivary Nucleus & Nucleus of
Lateral Leminiscus: Lateral Leminiscus: modulate transmission modulate transmission of auditory information to cochlear nerve by:of auditory information to cochlear nerve by:
1.1. Sending inhibitory fibers through Sending inhibitory fibers through vestibulocochlear nerve ending in Organ of vestibulocochlear nerve ending in Organ of CortiCorti
2.2. Establishing connection with motor Establishing connection with motor neurones supplying tensor tympani & neurones supplying tensor tympani & stapedius muscles stapedius muscles
NOTES ON AUDITORY PATHWAYNOTES ON AUDITORY PATHWAY
• Representation of cochlea is bilateral at Representation of cochlea is bilateral at all levels rostral to cochlear nucleiall levels rostral to cochlear nuclei
SS
LL
Late ral Late ral VestibulospinalVestibulospinal
tracttract
AHCsAHCs
MedialMedialVestibulospinalVestibulospinal
tracttract
NVPNVP(Thalamus)(Thalamus)
Vestibular AreaVestibular Area
Abducent NucleusAbducent Nucleus
Trochlear NucleusTrochlear Nucleus
Occulomotor NucleusOcculomotor Nucleus
VestibularVestibularGanglionGanglion
Vestibular nerveVestibular nerve
Hair CellsHair Cellsin Vestibule in Vestibule
& Semicircular & Semicircular CanalsCanals
AA
BB
A + B = Medial Longitudinal fasciculusA + B = Medial Longitudinal fasciculus
VESTIBULAR PATHWAYVESTIBULAR PATHWAY
Cochlear nerveCochlear nerve
MM
II
Median PlaneMedian Plane
AHCsAHCs
Vestibular NucleiVestibular Nucleiin Rostral in Rostral MedullaMedulla
ICPICPFlocculonodular Flocculonodular LobeLobe(Cerebellum)(Cerebellum)
NOTES ON NOTES ON VESTIBULAR PATHWAYVESTIBULAR PATHWAY
The first Order Neurones: The first Order Neurones: Cells of Cells of Vestibular ganglionVestibular ganglion located in Internal located in Internal Auditory MeatusAuditory Meatus
The second Order Neurones: The second Order Neurones: Cells of Cells of Superior, Lateral, Medial & Inferior Superior, Lateral, Medial & Inferior Vestibular NucleiVestibular Nuclei located beneath the located beneath the lateral part of floor of 4lateral part of floor of 4thth ventricle ventricle
NOTES ON NOTES ON VESTIBULAR PATHWAYVESTIBULAR PATHWAY
Medial Longitudinal fasciculus: formed Medial Longitudinal fasciculus: formed of both descending & ascending fibers:of both descending & ascending fibers:
1.1.Descending (medial vestibulospinal Descending (medial vestibulospinal tract) tract) to anterior horns cells to anterior horns cells for for control control of body posture & balanceof body posture & balance
2.2.Ascending Ascending to Occulomotor, Trochlear & to Occulomotor, Trochlear & Abducent Nuclei Abducent Nuclei (Motor Nuclei for (Motor Nuclei for extraoccular muscles for extraoccular muscles for coordination coordination of head & eye movementsof head & eye movements
NOTES ON NOTES ON VESTIBULAR PATHWAYVESTIBULAR PATHWAY
Vestibular area: Vestibular area:
1.Located in the lower part of postcentral the lower part of postcentral gyrus (head area) gyrus (head area)
2.Responsible for conscious awareness conscious awareness of vestibular sensationof vestibular sensation