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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.
© Dr. Srinivasan 2013
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.
© Dr. Srinivasan 2013
DIVISIONS
EXTERNAL
MIDDLE
INNER
EXTERNAL EAR
© Dr. Srinivasan 2013
PARTS
PINNA / AURICLE
EXTERNAL AUDITORY MEATUS
© Dr. Srinivasan 2013
Parts of Pinna
© Dr. Srinivasan 2013
Sensory innervation of Pinna
© Dr. Srinivasan 2013
Blood supply & Lymphatic drainage
BLOOD SUPPLY : Posterior auricular Superficial temporal Occipital
LYMPHATIC DRAINAGE: ANTERIOR ▪ Parotid nodes
POSTERIOR ▪ Mastoid nodes
© Dr. Srinivasan 2013
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
© Dr. Srinivasan 2013
Downward, forward & laterally
Otoscope
Umbo
Cone of light
© Dr. Srinivasan 2013
© Dr. Srinivasan 2013
© Dr. Srinivasan 2013
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?
© Dr. Srinivasan 2013
Tympanic sulcus
Anterior & posterior malleolar folds
Pars flaccida
Pars tensa
MIDDLE EAR
© Dr. Srinivasan 2013
Divided into 2 parts : Tympanic cavity Epitympanic recess
© Dr. Srinivasan 2013
Tympanic MembraneAn indicator of Middle Ear disease
What conclusions can be reached by
looking at the above tympanic
membranes?
© Dr. Srinivasan 2013
Middle Ear – Boundaries
ROOF Tegmen tympani
© Dr. Srinivasan 2013
FLOOR Internal jugular vein
© Dr. Srinivasan 2013
ANTERIOR Internal carotid artery
Auditory tube
Canal for tensor tympani
Exit for ▪ Chorda tympani N▪ Lesser petrosal N
© Dr. Srinivasan 2013
© Dr. Srinivasan 2013
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?
© Dr. Srinivasan 2013
© Dr. Srinivasan 2013
LATERAL Tympanic membrane
Chorda tympani N
© Dr. Srinivasan 2013
© Dr. Srinivasan 2013
MEDIAL Promontory
Fenestra vestibuli
Fenestra cochleae ▪ 2˚ tympanic membrane
Prominence of :▪ Facial nerve canal ▪ Lateral semicircular canal
© Dr. Srinivasan 2013
AUDITORY OSSICLES
© Dr. Srinivasan 2013
MALLEUS (C) Manubrium (2)
INCUS (B)
STAPES(A) Foot Process
What do you mean by Otosclerosis?
MUSCLES IN EAR
© Dr. Srinivasan 2013
Tensor tympani N. supply: branch from mandibular N
© Dr. Srinivasan 2013
StapediusN. Supply : branch from Facial N
INTERNAL EAR
© Dr. Srinivasan 2013
Labyrinth
Bony
Membranous
© Dr. Srinivasan 2013
Bony labyrinth Vestibule Semicircular canals Cochlea
© Dr. Srinivasan 2013
VESTIBULE
© Dr. Srinivasan 2013
© Dr. Srinivasan 2013
Semi circular canalsWhere is
macula and cristae?
What are Otoliths?
What is there function?
© Dr. Srinivasan 2013
Cochlea How many turns does cochlea make?
© Dr. Srinivasan 2013
What is Helicotrema?
© Dr. Srinivasan 2013
MEMBRANOUS LABYRINTH
AUDITORY NEURAL PATHWAY
© Dr. Srinivasan 2013
VESTIBULAR NERVE
COCHLEAR NERVE
© Dr. Srinivasan 2013
VESTIBULAR NUCLEI
© Dr. Srinivasan 2013
© Dr. Srinivasan 2013
© Dr. Srinivasan 2013
© Dr. Srinivasan 2013
© Dr. Srinivasan 2013
REFERENCES
Clinical Anatomy by Snell’s
Clinical Neuroanatomy by Snell’s
Gray’s Anatomy for Students
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