45 Questions
What is the location of the Primary Auditory Cortex?
BA 41, 42
Where are the low tones of pitch and frequency processed in the auditory pathway?
Anterolateral portion of Heschl’s gyrus
What is the function of the ventral acoustic stria?
Sends crossed and uncrossed fibers to the nuclei of trapezoid body and superior olivary nuclei
Where do the high tones of pitch and frequency stimulate the hair cells in the cochlea?
Basal portion
Where are the bipolar neurons located?
In the spiral ganglion
What is the name of the area responsible for auditory association and is located in BA 22?
Wernicke’s Area
What is the function of the cochlear nerve?
To transmit auditory information from the cochlea to the brainstem
What is the function of the dorsal cochlear nucleus in the central auditory pathway?
Receives fibers from the spiral ganglion
Where do the sequential projections of the fibers from the cochlea go to after the dorsal cochlear nucleus?
Medial portion of middle geniculate body
Where do the dorsal and ventral cochlear nuclei lie?
Lateral to the inferior cerebellar peduncle
What is the name of the pathway that involves the ventral acoustic stria?
Binaural pathway
What is the name of the structure where the inner hair cells are located?
Organ of Corti
What is the tonotopic representation of the auditory pathway?
High tones are processed in the basal portion of the cochlea, while low tones are processed in the apical portion
Where do the majority of fibers from the lateral lemniscus terminate?
In the contralateral inferior colliculus
What is the function of the medial geniculate body?
To act as the final sensory relay station
Where is the primary auditory cortex located?
In the dorsal surface of the superior temporal gyrus
What is the function of Wernicke's area?
To interpret sound
What is the name of the gyrus that houses the primary auditory cortex?
Heschl's gyrus
What is the result of a unilateral lesion in the auditory system?
Total deafness of the affected area
Where is the central unilateral lesion located in the brain?
Dorsolateral surface of the brainstem
Which part of the cochlea is responsible for processing low tones?
Upper/apical portion
What is the effect of a central unilateral lesion on hearing?
Impaired hearing on both ears, more marked on the opposite side of the lesion
What is the function of the Olivocochlear or Efferent Cochlear Bundle?
To regulate and inhibit impulses from the cochlea
What is the main function of the vestibular system?
Maintaining body balance
What is the name of the pathway that carries information about the frequency of auditory signals?
Monaural Pathway
What do the fibers of the auditory pathways do?
Cross to the opposite side
What is the name of the gyrus that is involved in the processing of auditory information?
Heschl's Gyrus
Which pathway is involved in maintaining body balance?
Vestibular pathway
What is the role of the vestibular pathway in eye movements?
Permitting the eye to remain focused on the target
Which pathway is responsible for analyzing the location of origin or direction of auditory signals?
Binaural Pathway
What is the result of a lesion in the vestibular pathway?
Loss of balance
What is the name of the complex that is the origin of the Olivocochlear or Efferent Cochlear Bundle?
Superior Olivary Complex
What is the coordination of the vestibular pathway with other afferent pathways?
Reflexive movement
What is the result of the inhibitory feedback system involving the Olivocochlear or Efferent Cochlear Bundle?
Auditory sharpening
Which part of the auditory pathway is involved in selective auditory attention?
Olivocochlear or Efferent Cochlear Bundle
What is the direction of the Olivocochlear or Efferent Cochlear Bundle?
Descending
Which vestibular receptors are stimulated when a person riding an elevator could sense even with their eyes closed that it is moving up or down?
Macula sacculi
Where is the primary auditory cortex located?
Superior temporal, superior part
A patient with a severed right vestibular nerve would MOST likely exhibit which of the following manifestations?
Spontaneous nystagmus to the left
Are projects from the vestibuloreticular pathway mainly contralateral?
False
Which pathway provides conscious awareness of the position and movements of the head in space?
Vestibulothalamocortical Pathway
Do the vestibulocerebellar and cerebellovestibular fibers pass through the juxtarestiform body?
True
Does the medial vestibulospinal tract project to the interneurons that synapse to the extensor motor neurons along the entire length of the spinal cord?
False
Does the ventral acoustic stria project bilaterally to the lateral lemnisci?
True
Does the spiral ganglion correspond to neuron 1 of the auditory pathway?
True
Study Notes
Central Auditory Pathway
- Receptors: Inner hairs at the organ of Corti
- Spiral Ganglion (N1): contains bipolar neurons whose dendrites connect to receptor cells (inner hair cells) and whose axons form the cochlear nerve
- Dorsal Cochlear Nucleus and Ventral Cochlear Nucleus (N2): receive projections from the cochlear nerve
- Dorsal Acoustic Stria: arises from dorsal cochlear nucleus, crosses to contralateral lateral lemniscus, and is part of the monaural pathway
- Intermediate Acoustic Stria: arises from ventral cochlear nucleus, crosses to contralateral lateral lemniscus, and is part of the monaural pathway
- Ventral Acoustic Stria: arises from ventral cochlear nucleus, sends crossed and uncrossed fibers to ipsilateral and contralateral nuclei of trapezoid bodies and superior olivary nuclei, and is part of the binaural pathway
- Inferior Colliculus (N3): receives projections from the acoustic striae and projects to the medial geniculate body (N4)
- Medial Geniculate Body (N4): final sensory relay station, projects to the primary auditory cortex (Brodmann Area 41,42)
- Primary Auditory Cortex (Brodmann Area 41, 42): anatomically known as Heschl's gyrus or anterior transverse temporal gyrus, located at the dorsal surface of the superior temporal gyrus
- Wernicke's Area (Brodmann Area 22): found in the posterior part of the superior temporal gyrus, contains the auditory association area, where sound is interpreted
Tonotopic Representation
- High tones of pitch and frequency: stimulate the hair cells in the most basal portion of the cochlea, followed by sequential projection of the fibers to the dorsal cochlear nucleus, medial portion of middle geniculate body (MGB), and posteromedial portion of Heschl's gyrus
- Low tones of pitch and frequency: reverse of the high tones
Auditory Lesions
- Unilateral lesion: results in total deafness of the affected ear
- Central unilateral lesion: involves lesions in the cortex, medial geniculate body, or lateral lemniscus, results in central hearing loss, with more marked impairment on the opposite side of the lesion
Vestibular System
- Functions: maintains body balance, coordinates eye, head, and body movements, permits the eye to remain focused on the target even if the head moves
- Afferent pathways: dorsal column pathway, spinocerebellar pathway, visual input from retina
- Classification of Auditory Pathway:
- Monaural Pathway: ascending pathway, consists of projections from the dorsal and intermediate acoustic striae, carries information about the frequency of auditory signals
- Binaural Pathway: ascending pathway, consists of projections from the ventral acoustic striae, analyzes the location of origin or direction of auditory signals
- Olivocochlear or Efferent Cochlear Bundle: descending pathway, from the primary auditory complex to the organ of Corti, functions as an inhibitory feedback system involving regulation and inhibition of impulses from the cochlea
Test your knowledge on the auditory pathway, including the structure and function of the inner hair cells, spiral ganglion, and cochlear nerve. Explore how sound signals are transmitted from the ear to the brainstem.
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