© 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 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  SNELL’s CLINICAL ANATOMY – 7 th 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  EXTERNAL  MIDDLE  INNER

© Dr. Srinivasan 2013  PINNA / AURICLE  EXTERNAL AUDITORY MEATUS

© Dr. Srinivasan 2013

 BLOOD SUPPLY :  Posterior auricular  Superficial temporal  Occipital  LYMPHATIC DRAINAGE:  ANTERIOR ▪ Parotid nodes  POSTERIOR ▪ Mastoid nodes

© Dr. Srinivasan 2013  Not straight  Outer 2/3 – Cartilage  Inner 1/3 – Bony (Temporal)  N. supply  Auriculotemporal  Vagus How do you examine Ext. Audiotry Meatus?

© Dr. Srinivasan 2013  Downward, forward & laterally  Otoscope  Umbo  Cone of light

© 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

© Dr. Srinivasan 2013  Divided into 2 parts :  Tympanic cavity  Epitympanic recess

© Dr. Srinivasan 2013 What conclusions can be reached by looking at the above tympanic membranes?

© Dr. Srinivasan 2013  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

 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

 LATERAL  Tympanic membrane  Chorda tympani N

© Dr. Srinivasan 2013

 MEDIAL  Promontory  Fenestra vestibuli  Fenestra cochleae ▪ 2˚ tympanic membrane  Prominence of : ▪ Facial nerve canal ▪ Lateral semicircular canal

© Dr. Srinivasan 2013

 MALLEUS (C)  Manubrium (2)  INCUS (B)  STAPES(A)  Foot Process What do you mean by Otosclerosis?

© Dr. Srinivasan 2013  Tensor tympani  N. supply: branch from mandibular N

© Dr. Srinivasan 2013  Stapedius  N. Supply : branch from Facial N

© Dr. Srinivasan 2013  Labyrinth  Bony  Membranous

© Dr. Srinivasan 2013  Bony labyrinth  Vestibule  Semicircular canals  Cochlea

© Dr. Srinivasan 2013  VESTIBULE

© Dr. Srinivasan 2013

 Semi circular canals Where 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

© Dr. Srinivasan 2013  VESTIBULAR NERVE  COCHLEAR NERVE

© Dr. Srinivasan 2013

VESTIBULAR NUCLEI

© Dr. Srinivasan 2013

 Clinical Anatomy by Snell’s  Clinical Neuroanatomy by Snell’s  Gray’s Anatomy for Students