© Dr. Srinivasan 2013 To describe the parts of the external, middle and internal ear and its contents. To understand the role of tympanic membrane,

EAR

© Dr. Srinivasan 2013

OBJECTIVES

To describe the parts of the external, middle and internal ear and its contents.

To understand the role of tympanic membrane, ear ossicles and the internal ear.

To understand the pathway taken by the vestibular and cochlear nerves and its relation with higher centers

To describe the boundaries, contents, muscles their nerve supply and their actions on hearing.


RECOMMENDED READING SNELL’s CLINICAL ANATOMY – 7th edition

LECTURE NOTES taken during class!!!

Most of the slides contain pictures. This is done purposefully. Students are requested to listen carefully in the lecture and take notes . Supplement the picture with lecture notes and the text book.

If any clarification needed please approach the faculty after the class.


DIVISIONS

EXTERNAL

MIDDLE

INNER

EXTERNAL EAR


PARTS

PINNA / AURICLE

EXTERNAL AUDITORY MEATUS


Parts of Pinna


Sensory innervation of Pinna


Blood supply & Lymphatic drainage

BLOOD SUPPLY : Posterior auricular Superficial temporal Occipital

LYMPHATIC DRAINAGE: ANTERIOR ▪ Parotid nodes

POSTERIOR ▪ Mastoid nodes


External Auditory Meatus

Not straight

Outer 2/3 – Cartilage

Inner 1/3 – Bony (Temporal)

N. supply Auriculotemporal VagusHow do you examine Ext.

Audiotry Meatus?

TYMPANIC MEMBRANE


Downward, forward & laterally

Otoscope

Umbo

Cone of light




Where is Chorda Tympani N located? What is it’s significance?

Where will you place incision in case you want to enter into Middle Ear?


Tympanic sulcus

Anterior & posterior malleolar folds

Pars flaccida

Pars tensa

MIDDLE EAR


Divided into 2 parts : Tympanic cavity Epitympanic recess


Tympanic MembraneAn indicator of Middle Ear disease

What conclusions can be reached by

looking at the above tympanic

membranes?


Middle Ear – Boundaries

ROOF Tegmen tympani


FLOOR Internal jugular vein


ANTERIOR Internal carotid artery

Auditory tube

Canal for tensor tympani

Exit for ▪ Chorda tympani N▪ Lesser petrosal N



POSTERIOR Aditus to mastoid antrum

Pyramid

Stapedius

Entry of Chorda tympani N

What happens if pus in Middle Ear

accumulates over a long time?

Where does it spread?



LATERAL Tympanic membrane

Chorda tympani N



MEDIAL Promontory

Fenestra vestibuli

Fenestra cochleae ▪ 2˚ tympanic membrane

Prominence of :▪ Facial nerve canal ▪ Lateral semicircular canal


AUDITORY OSSICLES


MALLEUS (C) Manubrium (2)

INCUS (B)

STAPES(A) Foot Process

What do you mean by Otosclerosis?

http://www.google.ae/url?sa=i&source=images&cd=&cad=rja&docid=ttNpHET9bLf2hM&tbnid=ulPkDJXgROmOVM:&ved=0CAgQjRwwADhA&url=http%3A%2F%2Fvoyager.dvc.edu%2F~nmiller%2Fbiosc139%2Fmodels%2F19_models_ear%2Fear.html&ei=b5WKUd39A9HLrQfj54HIDg&psig=AFQjCNEGwA8v9K-Ec8M7yMWaOdFXCfwchg&ust=1368123119128311

MUSCLES IN EAR


Tensor tympani N. supply: branch from mandibular N

http://audilab.bmed.mcgill.ca/~daren/media/ossicles_tendons.wrl


StapediusN. Supply : branch from Facial N

INTERNAL EAR


Labyrinth

Bony

Membranous


Bony labyrinth Vestibule Semicircular canals Cochlea


VESTIBULE



Semi circular canalsWhere is

macula and cristae?

What are Otoliths?

What is there function?


Cochlea How many turns does cochlea make?


What is Helicotrema?


MEMBRANOUS LABYRINTH

AUDITORY NEURAL PATHWAY


VESTIBULAR NERVE

COCHLEAR NERVE


VESTIBULAR NUCLEI






REFERENCES

Clinical Anatomy by Snell’s

Clinical Neuroanatomy by Snell’s

Gray’s Anatomy for Students

Documents

© Dr. Srinivasan 2013 To describe the parts of the external, middle and internal ear and its contents. To understand the role of tympanic membrane,