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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
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
http://www.spineuniverse.com/displayarticle.php/article1023.html
Anatomical directions

Anterior/Ventral: Front

Posterior/Dorsal: Back

Inferior: Bottom

Superior: Top

Lateral: Away from median plane

Medial: Toward the median plane
Anatomy of the auditory system

Contained in the temporal
bone

Located on the sides of
the skull
Parts of the temporal bone

Squamous

Mastoid

Tympanic

Petrous
Medial view of right ear.
Lateral view of right ear Note: IAM is internal auditory
meatus, which is different from the
external auditory meatus.
Anatomy of the ear

http://www.iurc.montp.inserm.fr/cric51/audition/english/ear/fear.htm

http://www.wiley.com/legacy/college/bio/tortora366927/resources/st
udent/anatomydrill/ch16.html
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
External ear

Consists of

Auricle or Pinna: Mostly
cartilage

External auditory
canal/meatus
http://www.ghorayeb.com/Ana
tomyAuricle.html
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
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
External ear functions
1.
2.
Modifies the spectrum of incoming sounds.
a.
Resonance of external auditory meatus
b.
Head related transfer functions
Protection to middle and inner ear structures
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
External ear functions
1.
2.
Modifies the spectrum of incoming sounds.
a.
Resonance of external auditory meatus
b.
Head related transfer functions
Protection to middle and inner ear structures
Head-related transfer functions

Inter-aural amplitude/level difference

Inter-aural time difference
Important for sound localization