Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Human Anatomy ppt lectures Topic 43 Auditory Pathway Notes. - anatomy ppt free download human anatomy ppt lectures, medicine notes ppt, anatomy handwritten notes pdf, mbbs 1st year anatomy notes pdf download, best anatomy notes pdf, human anatomy notes pdf, anatomy easy notes pdf, anatomy notes online, anatomy short notes, Anatomy ppt, Powerpoint Presentations and lecture notes.
Learning objectives
?Receptors
?Ascending pathway of hearing
?Involvement of nuclei at different level
?Applied anatomy
2
Auditory pathway
?Transmits auditory stimulus from hearing receptors
(organ of corti`s) to auditory area in cerebral cortex.
1. Organ of Corti (receptor)
2. Dorsal & ventral cochlear nuclei
3. Trapezoid body & Superior olivary nuclei
4. Lateral lamniscus
5. Inferior colliculus
6. Medial geniculate body
7. Auditory radiation
8. Auditory cortex
3
Auditory pathway
?Cochlear nu-receptors- hair cells in Organ of Corti
?1st order neuron- spiral ganglion- bipolar neurons ?
peripheral process- hair cells of spiral ganglion ? central
processes & axons - cochlear nerve- bifurcates & terminate
in Dorsal & Ventral Cochlear Nu ? 2nd order neurons -
dorsal & ventral ? axons CROSS & few uncrossed in dorsal
part of Lower part of pons - Superior Olivary nucleus-
?3rd Neuron ? Superior Olivary Nucleus - lateral lemniscus
Formation of Trapezoid body- In dorsal part of pons ?
intermediate /dorsal acoustic striae-nucleus of trapezoid
body.
?Lateral lemniscus ? terminate at ?Inferior Colliculus (MB)
?Inferior colliculus - 4th order of neuron- (Inf Brachiaum)
Auditory pathway
?Inferior colliculus - 4th Order Neuron - center for
auditory reflexes Medial Geniculate body
through inferior brachium.
?Medial Geniculate body - 5th order of neuron & is -
Final Relay Station - hearing pathway.
?5th order of neuron ? starts from MGB- forms
acoustic radiation -reaches- acoustic area of
cerebral hemisphere ?
?Acoustic area accepts bilateral impulses.
?Temporal lobe - Superior Temporal gyrus area
41,42.
8
9
Auditory area....
?Primary auditory area - floor of post ramus of lateral
sulcus.
?Superior surface of superior temporal gyrus has two
transverse temporal gyri (Heschl's gyrus)
? area-41 & 42 receives inputs from medial geniculate
body.
Auditory areas
?Primary auditory area ? area 41
?Superior temporal gyrus ? bilateral representation
?Detection of direction & frequency of sound.
?Lower frequencies are located in anterior/lateral
part & higher frequencies are located in
posterior/medial part
?Auditory association area - area 42 ? co-relates
and comprehension of present stimulus to past
ones
?Higher Auditory association area - area 22 ?
Wernicke's area- comprehension of spoken
language & interpretation of sound.
Auditory areas
?Lesion of primary auditory area 41 & 42 of one side
produces bilateral partial deafness, b/o bilateral
receiving of inputs via medial geniculate body.
?Auditory association cortex- area 22 , Wernicke's
speech area. Interpretation of sounds on past
experiences. Sensory aphasia.
?Olfactory area- 28 , lateral olfactory stria & gyrus
,anterior part of parahippocampal gyrus & uncinate
gyrus.
?Area 8 ? frontal eye field
?Area 44 & 45 ? Broca's speech area ? motor
speech area in dominant cerebral hemisphere.
?Prefrontal cortex- (area - 9-12)
?Depth of feeling
?Foresightedness
?Tactfulness
?Mature judgement
?Pleasure & displeasure
?Lesion of prefrontal cortex (9 -12) - Lack of self
responsibility ,Vulgarity of speech, euphoria ,
clownish behaviour
?Area-40- Astereognosis & tactile aphasia
?Area-39 ? word blindness ? unable to read
words even if were written by one self
?Area 22 - word deafness - sensory aphasia.
Decreased interpretation of sounds/words and
increased frequency of word produced....
?Area 44 & 45 ? motor aphasia
Speech area....
Wernicke's area- 22, dominant hemisphere ,
interpretation of spoken ,written ,symbols & signs.
Allows understanding of written & spoken language.
Angular gyrus - interconnects -visual area & auditory
areas.
Wernicke's is necessary for- language
comprehension while Broca's area, 44, language
production. Superior longitudinal fasciculus or
arcuate fasciculus interconnect these two areas.
Sensory aphasia- unable to understand written or
spoken words with normal vision/hearing.
Speech area's.....
?Apraxia- parietal lobe -impairment of performance
of learned movements.
?Wernicke's aphasia- inability to understand spoken or
written words ? Broca's ok- uses all meaningless and
incorrect words...no meaning. Called-fluent aphasia
or receptive aphasia ,
?Broca's aphasia- unable to articulate words-
nonfluent aphasia, hesitant aphasia /distorted-
?What they wish to say but can not speak.
?Global aphasia- extensive damage to cortex
This post was last modified on 05 April 2022