2. Parts of the auditory system
Peripheral
External ear
Middle ear
Inner ear
Auditory nerve
Central
Cochlear nucleus
Superior olivary complex
Lateral leminiscus
Inferior colliculus
Medial geniculate body
Auditory subcortex
Cortex
Interhemispheric pathways

3. Anatomical terms Planes of section: Frontal/Coronal: Front and back
Sagittal: Left and right
Median/Midsagittal: Through the center
Axial/Horizontal/Transverse: Upper and lower

4. Anatomical directions
Anterior/Ventral: Front
Posterior/Dorsal: Back
Inferior: Bottom
Superior: Top
Lateral: Away from median plane
Medial: Toward the median plane

5. Anatomy of the auditory system
Contained in the temporal bone
Located on the sides of the skull

6. Parts of the temporal bone
Squamous
Mastoid
Tympanic
Petrous
Medial view of right ear.
Note: IAM is internal auditory
meatus, which is different from the
external auditory meatus.
Lateral view of right ear

7. Anatomy of the ear

8. Parts of the auditory system
Peripheral
External ear
Middle ear
Inner ear
Auditory nerve
Central
Cochlear nucleus
Superior olivary complex
Lateral leminiscus
Inferior colliculus
Medial geniculate body
Auditory subcortex
Cortex
Interhemispheric pathways

9. External ear Consists of Auricle or Pinna: Mostly cartilage
External auditory canal/meatus

10. Parts of the Pinna Concha: Bowl or deep central portion
Helix: Prominent ridge that begins superior to the opening of the canal and runs around the pinna
Antihelix: Interior ridge parallel to the helix
Triangular fossa: Triangular depression formed anteriorly and superiorly by the helix
Lobule: Most inferior part of the pinna
Tragus: Small flap at the anterior side of the concha

11. External auditory meatus
Length is approximately 28 mm
Diameter is approximately 7 mm
Not perfectly straight
Ends in the tympanic membrane
Outer half of the canal formed by cartilage
Skin secretes cerumen
Medial part formed by bone from the squamous and tympanic portions of the temporal bone

12. External ear functions
Modifies the spectrum of incoming sounds.
Resonance of external auditory meatus
Head related transfer functions
Protection to middle and inner ear structures

13. Resonance of ear canal Resonance of ear canal: Around 2.5 kHz
Resonance of the concha: Around 5 kHz
Net effect: Boost in frequency region between 1.7 and 7 kHz

15. External ear functions
Modifies the spectrum of incoming sounds.
Resonance of external auditory meatus
Head related transfer functions
Protection to middle and inner ear structures

16. Head-related transfer functions
Inter-aural amplitude/level difference
Inter-aural time difference
Important for sound localization