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Anatomy of ear BY Ms.Sapna Rani
- 1. ANATOMY AND PHYSIOLOGY of EAR AND *Disorder Of The Hearing* (Established under Section 3 of UGC Act, 1956) (Accredited by NAAC with Grade A++) Submitted To: Submitted By: Prof. (Dr.) Sumeet Gupta Ms. Sapna Dean & Principal Assistant Professor MMCPMM(DU) Pharmacology Mullana Ambala, Haryana
- 2. CONTENTS i. Major Divisions of the Ear ii. Outer Ear iii. Function of Outer Ear iv. External Auditory Meatus v. Middle Ear vi. Function of Middle Ear vii.Function of Inner Ear viii.Organ of Corti ix. Hair Cells x. OHC vs. IHC Function xi. Cranial Nerve xii. Label the Parts of the Ear* xiii.How Does the Ear Work? xiv.Steps to Hearing:*
- 3. Major Divisions of the Ear Peripheral Mechanism Central Mechanism Outer Ear Middle Ear Inner Ear VIII Cranial Nerve Brain
- 5. Pinna
- 6. Pinna The visible portion that is commonly referred to as "the ear" Helps localize sound sources Directs sound into the ear Each individual's pinna creates a distinctive imprint on the acoustic wave traveling into the auditory canal
- 7. Function of Outer Ear Collect sound Localization Resonator Protection Sensitive (earlobe)
- 8. External Auditory Meatus Extends from the pinna to the tympanic membrane About 26 millimeters (mm) in length and 7 mm in diameter in adult ear. Size and shape vary among individuals. Protects the eardrum Resonator Provides about 10 decibels (dB) of gain to the eardrum at around 3,300 Hertz (Hz). The net effect of the head, pinna, and ear canal is that sounds in the 2,000 to 4,000 Hz region are amplified by 10 to 15 dB. Sensitivity to sounds greatest in this frequency region Noises in this range are the most hazardous to hearing
- 9. Cerumen The purpose of wax: Repel water Trap dust, sand particles, micro- organisms, and other debris Moisturize epithelium in ear canal Antibiotic, antiviral, antifungal properties Clearance ear canal
- 10. Middle Ear Tympanic Cavity Tympanic Membrane Ossicles Middle Ear Muscles Eustachian Tube Mastoid Virtual Tour of the Ear Middle Ear Cavity Ossicles Middle Ear Muscles Mastoid Eustachian Tube Function Amplifier Cholesteatoma Temporal bone fractures Otitis Media PE tubes Otosclerosis
- 11. Function of Middle Ear Conduction Conduct sound from the outer ear to the inner ear Protection Creates a barrier that protects the middle and inner areas from foreign objects Middle ear muscles may provide protection from loud sounds Transducer Converts acoustic energy to mechanical energy Converts mechanical energy to hydraulic energy Amplifier Transformer action of the middle ear only about 1/1000 of the acoustic energy in air would be transmitted to the inner-ear fluids (about 30 dB
- 12. Tympanic Membrane The eardrum separates the outer ear from the middle ear Creates a barrier that protects the middle and inner areas from foreign objects Cone-shaped in appearance about 17.5 mm in diameter The eardrum vibrates in response to sound pressure waves. The membrane movement is incredibly small as little as one-billionth of a centimeter
- 13. Eustachian Tube The eustachian tube connects the front wall of the middle ear with the nasopharynx The eustachian tube also operates like a valve, which opens during swallowing. This equalizes the pressure on either side of the eardrum, which is necessary for optimal hearing. Without this function, a difference between the static pressure in the middle ear and the outside pressure may develop, causing the eardrum to displace inward or outward This reduces the efficiency of the middle ear and less acoustic energy will be transmitted to the inner ear.
- 14. Ossicles Malleus (hammer) Incus (anvil) Stapes (stirrup) smallest bone of the body
- 15. Transformer/Amplifier Transform the vibrating motion of the eardrum into motion of the stapes. The middle ear enhances the transfer of acoustical energy in two ways: The area of the eardrum is about 17 times larger than the oval window The effective pressure (force per unit area) is increased by this amount. The ossicles produce a lever action that further amplifies the pressure Without the transformer action of middle ear, about 1/1000 of acoustic energy in air transmitted to inner-ear fluids (about 30 dB loss). Malleus and incus vibrate together, transmitting the sound waves from the eardrum to the footplate of the stapes (this pushes the oval window in and out)(mechanical energy)
- 16. Otosclerosis Develops most frequently between ages of 10 and 30. About 10–15% of patients have unilateral loss. Affects women more frequently than men by a ratio of 2:1. Pregnancy once thought to be a risk factor for the development and / or worsening of otosclerosis…recent studies have disputed this. May progress to nerve deafness called cochlear otosclerosis.
- 17. Inner Ear Auditory Vestibular Vestibular semicircular canals utricle and saccule Cochlear
- 18. Function of Inner Ear Convert mechanical sound waves to neural impulses that can be recognized by the brain for: Hearing Balance
- 19. Balance Linear motion Rotary motion
- 20. Cochlea The cochlea resembles a snail shell and spirals for about 2 3/4 turns around a bony column Within the cochlea are three canals: Scala Vestibuli Scala Tympani Scala Media
- 21. Organ of Corti
- 22. Organ of Corti This is the organ of hearing. It lies on the basilar membrane which forms the lower boundary of cochlear duct. The cochlear duct is bounded above by the vestibular membrane. The basilar membrane has tightly stretched fibers, the shorter fibers are located on the base and the longer ones at the apex. The organ of corti contains numerous receptors hair cells which mediates the transformation of the vibrations of the basilar membrane into nerve impulses.
- 23. Organ of Corti
- 24. Organ of Corti
- 25. Hair Cells Outer Hair Cells Inner Hair Cells
- 26. OHC vs. IHC Function
- 27. Cranial Nerve Auditory Branch Vestibular Branch Virtual Tour of the Ear Auditory Branch Vestibular Branch Spiral ganglion Acoustic Tumors
- 28. Label the Parts of the Ear* Pinna Ear Canal Eardrum Auditor y Nerve Cochle a Hamme r Anvil Stirrup Outer Ear Middle Ear Inner Ear
- 29. How Does the Ear Work? Animation 1 Animation 2 Animation 3
- 30. Steps to Hearing:* 1. Vibrations move through the outer ear canal and vibrate the eardrum. 2. The eardrum passes its energy through a chain of three tiny bones, the anvil, hammer, and stirrup, in the middle of the ear. 3. The anvil, hammer, and stirrup pass the energy onto the cochlea. 4. The vibrations activate hair cells and fluid inside the cochlea. 5. Electrical signals are sent to the brain through the auditory nerve.
- 31. THANK YOU