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
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.
TUMOR
Large TumorAbnormal Standard ABR
Small TumorAbnormal Standard
ABR
Small TumorNormal Standard ABR
Standard ABR
HIGH-FREQUENCY
FIBERS
Facial Nerve Sup. Vest Nerve
Inf. Vest NerveAcoustic Nerve
Cross-section of Internal Auditory Canal
