Transcript The Ear - Augustana College

The Ear
Perry C. Hanavan
Outer Ear
• Peripheral
– Outer ear
– Middle ear
– Inner ear
– Auditory nerve
• Central
– Brainstem
– Midbrain
– Cerebral
Peripheral
Outer Ear - Pinna
Middle Ear - Tympanum
Middle Ear – Tympanic Membrane
Middle Ear – Ossicles
Middle Ear - Ossicles
Middle Ear – Ossicles - Malleus
Middle Ear – Ossicles - Incus
Middle Ear – Ossicles - Stapes
Middle Ear
Inner Ear - Osseous
Inner Ear - Membranous
Inner Ear - Labyrinth
Inner Ear – Organ of Corti
Cochlear Structures
Inner Ear – Organ of Corti
Basilar Membrane
• Traveling wave
Inner Ear – OHC & IHC
• IHC
– Non-motile
– Afferent
– Responds to
loud sounds
• OHC
– Motile
– Efferent
– Responds to
soft sounds
OHCs
Two Theories of Motility
• Somatic prestin
motor
• Hair bundle
motor
Tip-links –Hair Bundle Motor
<<<IHC
OHC >>>
Tip Link Structure
• Tip Link Structure
Hair Bundle Motor
Tip-links
Auditory Nerve
2 Types of Auditory Neurons
Paul Fuchs YouTube
Paul Fuchs YouTube
Type I
Type II
Standard ABR
Cross-section of Internal Auditory
Canal
Sup. Vest Nerve
Facial Nerve
HIGHFREQUENCY
FIBERS
Acoustic Nerve
Large Tumor
Abnormal Standard ABR
TUMOR
The wave V latency used in the
standard ABR IT5 and I-V delay
measures is dominated by neural
activity from the high-frequency
regions of the cochlea. Thus, unless
the tumor affects these high-frequency
fibers sufficiently, standard ABR
latencies will be normal.
Inf. Vest Nerve
Small Tumor
Abnormal Standard
ABR
Small Tumor
Normal Standard ABR