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  1. 1. The Anatomy of the Ear
  2. 2. • provides the senses of equilibrium and hearingequilibrium- informs us of the position of the body in space by monitoring gravity, linear acceleration, and rotation.hearing- enables us to detect and interpret soundwaves.
  3. 3. 3 Anatomical Regions of the Ear1. External Ear2. Middle Ear3. Inner Ear
  4. 4. The External Ear
  5. 5. - visible portion of the ear- collects and directs soundwaves to the eardrumComposed of:1. the auricle, or pinna, and2. the external acoustic meatus.
  6. 6. The Pinna- surrounds the entrance tothe external auditory canal- supported by elasticcartilage- protects the opening ofthe canal- collects and conveysoundwaves to thetympanic membrane
  7. 7. The PinnaFeatures: 1. Concha 2. Helix 3. Crus of Helix 4. Lobule 5. Antihelix 6. Scapha 7. Tragus 8. Antitragus 9. Intertragic notch
  8. 8. The External Auditory Meatus- Extends from the concha to the tympanic membrane.- Its length, from the floor of the concha, is approximately 2.5 cm and from the tragus about 4 cm.- It has two structurally different parts, the lateral third being cartilaginous and the medial two-thirds osseous.
  9. 9. The External Auditory Meatus• Features:1. skin2. Hair3. Sweat Glands4. Sebaceous Glands /Ceruminous Glands -slows down the growth of bacteria and reduces the chances of infection
  10. 10. Tympanic Membrane- separates the external and middle ear- transmits soundwaves along the auditory ossicles to the inner ear.- the deepest part of which is the umbo where the tip of the handle of the malleus is attached.
  11. 11. The Middle Ear
  12. 12. Middle Ear- also known as the tympanic cavity- space in the petrous temporal bone lined by mucous membraneThe cavity has two parts:1. the tympanic cavity proper, opposite the membrane, and2. an epitympanic recess, contains the malleus and incus.
  13. 13. Walls of the Middle EarAnterior - opens directly to the eustachain tubePosterior - presents a large opening - aditus - that leads to the tympanic antrum, where the stapedius m. is found.Lateral - tympanic membraneMedial - foramen ovale of the vestibuleRoof - tegmen tympani
  14. 14. Middle EarMuscles:1. Tensor Tympani M.2. Stapedius M.Bones:1. Malleus (hammer)2. Incus (anvil)3. Stapes (stirrup)
  15. 15. The Inner Ear
  16. 16. The Inner Ear- located in the petrous part of the temporal bone- the senses of equilibrium and hearing are provided by the receptors of the inner ear, which lies in the membranous labyrinth.
  17. 17. The Inner EarTwo Labyrinths:1. Bony labyrinth2. Membranous labyrinth
  18. 18. The Bony Labyrinth
  19. 19. The Bony Labyrinth1. Bony Labyrinth - about 3 mm. thick that is as hard as ivory. 3 parts: a. Vestibule b. Semicircular Canals c. Cochlea
  20. 20. The Vestibule of the Bony Labyrinth- the central part of the bony labyrinth behind the cochlea containing the fenestra vestibuli enclosed by the stapes.- contains the utricle and saccule which contain receptors for the sensation of gravity and linear accelaration.
  21. 21. The Semicircular Canals- 3 horseshoe- shaped fluid- filled canals that contain receptors stimulated by the rotation of the head.
  22. 22. The Cochlea - the bony cochlea contains the cochlear duct of the membranous labyrinth.- contains receptors in the cochlear ducts that provide the sense of hearing.
  23. 23. The Membranous Labyrinth
  24. 24. Membranous labyrinth- lies within the bony labyrinth and consisting of sacs that contain fluid known as endolymph.- The fluid that separates the bony and membranous labyrinth is known as perilymph. This is made up of: a. Scala Tympani b. Scala Vestibuli c. Cochlear duct - organ of corti
  25. 25. Membranous labyrinth
  26. 26. The Cochlea