Anatomy of inner Ear: Anatomy of inner Ear Inner Ear Lies in Petrous part of temporal bone. Inner Ear consist of two Parts 1/ Bony (Osseous ) Labyrinth. 2/ Membranous Labyrinth Slide 2: Embryology: Thickening of ectoderm. Pit and vesicle formation,sinks deep to mesenchyma. Pit and then vesicle, sinks to deep mesenchyma Embryology: Thickening of ectoderm. Slide 3: The vesicle forms Membranous Labyrinth The surrounding Mesenchyma forms the Bony Labyrinth, Hardest bone. Perilymphatic space Slide 4: Perilymph Bony(osseous labyrinth): Bony(osseous labyrinth) Vestibule: central area between lateral termination of IAM and tympanic cavity. Size: ASpirin tablet. Communicates anteriorly with scala vestibule And posteriorly with 5 openings of SCC> Slide 6: Medial wall of vestibule: 8th nerve Lateral wall, oval window and round window. Slide 8: Medial wall of vestibule. perforations for 8th nerve. The front half of medial wall has Saccule of membranous labyrinth the posterior half contains Utricle orifice of aqueduct of vestibule. Slide 10: The Semicircular Canals: Posterior end of bony Labyrinth. 3 SCC, Lateral, Posterior and Superior, 2/3 of a circle Slide 11: Each canal has 2 opening to vestibule one opening of each canal is dilated called Ampulary end Non ampulary ends of Posterior and superior canal make common opening. total 5 openings to vestibule Cochlea: Cochlea Anterior part of bony labyrinth Hollow tube taking 2and3/4 turn round Modiolus. where the tube is applied to modiolus ,crest of bone like flange of screw projects to lumen dividing almost to 2 tube, Helicotrema Slide 13: Modiolus abuts on the cholera area of IAM Cochlear nerve enters in the centre and periphery. distance from base to apex is 5 mm. length of cochlear duct is 30 mm. Slide 14: Scala vestibule scala tympani Membranous Labyrinth: Membranous Labyrinth Otic vesicle. 2 out growths Anterior forms cholera duct(scala media)and endolymphatic duct and sac Posterior part forms sacule,utricle and 3 scc . Slide 16: Semicircular canals. superior and lateral have 3 openings, crus commune and 2 ampulary ends,lat scc have 2 openings to utricle . total 5 opening to utricle. Slide 17: Cochlear duct . starts at saccule by canalis reunion. Basilar membrane,attaches to spiral lamina aand lateral wall of bony cochlea.and divide the chclear duct to scala vestibule and tympani Slide 18: basilar membrane epithelium show modification ,organ of corti Scala media triangular on section Slide 20: Sensory areas in membranous ssc and cochlea. 1/ Crista ampullaris of ssc 2/Macula in utricle and saccule. 3/organ of corti Slide 21: Blood supply of internal Ear. internal auditory artery, branch of anterior cerbellar artery, cochlear and vestibular branches veins of same name drain to petrosal sinus Slide 22: Vestibular cochlear nerve.