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Exploring the Intricacies of Ear Structure

Dive into the detailed anatomy of the ear, from the outer ear's protective mechanisms to the inner ear's auditory nerve pathway. Discover how sound waves are processed and understand equilibrium functions. Explore the causes and types of deafness.

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Exploring the Intricacies of Ear Structure

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  1. The Ear Damaris Alas Lusine Zhamharyan Matt Marquez Period 3

  2. Ear Structure • Made up of three parts • Outer ear (external) • Middle ear • Inner ear

  3. Outer (External) Ear • Pinna (outer ear cartilage) • External Auditory Canal • Lined with hairs and ceruminous glands, which prevent objects and insects from entering. • Both funnel sound waves towards the tympanic membrane (eardrum), causing it to vibrate.

  4. Middle Ear (Tympanic Cavity) • Air filled space located in the temporal bone of the skull • Contains 3 small auditory bones: • Malleus • Incus • Stapes • Auditory Tube • Drains fluid • Adjusts ear pressure

  5. Middle Ear Ossicles • Inter-articulated bones of the middle ear that amplify the vibration of the eardrum and send them to the internal ear • Attached by ligaments • Malleus attached to ear drum • Stapes attached to oval window of inner ear

  6. Middle Ear… Adjusting Ear Pressure • The auditory tube maintains equal pressure in the ear • Does this by: • Draining fluid from the middle ear into the throat • Allows the air to pass between the tympanic cavity and the outside of the body by way of the throat and mouth

  7. Middle Ear… Protective Mechanism • Tympanic Reflex • Involuntary muscle contractions after loud sounds • Ossicles are pulled on causing them to become more rigid and less effective • Vibrations are dampened

  8. Inner Ear • Composed of a labyrinth • Osseous Labyrinth (Bony) • Secretes Perilymph • Membranous Labyrinth • Lies within the osseous • Contains Endolymph • Main Structures: • Cochlea • Semicircular Canals • Vestibule

  9. Inner Ear … Cochlea • Shaped like a snail shell • Bony labyrinth is divided in two • Upper: ScalaVestibuli • Oval Window to the apex • Vestibular Membrane • Lower: Scala Tympani • Apex to the round window • Basilar Membrane • Both connected by helicotrema • Membranous labyrinth lies in the middle, called the Scala Media (cochlear duct)

  10. Inner Ear … Cochlea

  11. Inner Ear … Cochlea (cont.) • Houses the organ of Corti • 16,000 hearing receptor hair cells • Lies on the upper surface of the basilar membrane • Hair cells extend into the cochlear duct

  12. Auditory Nerve Pathway • Carries the signal into the brainstem and synapses in the cochlear nucleus • From there the auditory information splits into motion and form procession • Auditory nerve fibers going to the ventral cochlear nucleus synapse on their target cells with giant, hand like terminals • Two streams: • Cells project to a collection of nuclei in the medulla called the superior olive

  13. Auditory Nerve • Vestibulocochlear • located in the internal auditory canal • responsible for both hearing and balance and brings information from the inner ear to the brain • Two special organs help the nerve function properly: • cochlea and vestibular apparatus

  14. Equilibrium • Comes from 2senses: • Static Equilibrium • Senses position of the head • Maintains stability and posture • Dynamic Equilibrium • Senses motion • Aids in maintaining balance

  15. Static Equilibrium • Comes from: • Utricle and Saccule in Vestibule • Contain Macula • Hair cells which act as sensory receptors • Covered in layer of a gelatinous matrix • Otoliths embedded on surface • Weigh down on membrane making it more responsive to changes

  16. Static Equilibrium

  17. Dynamic Equilibrium • Comes from: • Ampullae in semicircular canals • Communicate with the utricle • Contain Crista Ampullaris • Also contains hair cells that extend into a gelatinous matrix (cupula)

  18. Dynamic Equilibrium

  19. Sound Wave Pathway

  20. Sound Wave Pathway

  21. Deafness • Can be: • Acquired • Picked up, and caused by outside factor • Exposed to intense, pure tone • Inherited • Born with • More than 100 types • One in a thousand newborn are deaf because of genetic defects • 2 Types: • Sensorineural • Damage to the cochlea or auditory nerve • Conductive: • Interference with transmission of vibrations in inner ear

  22. Work Cited "Auditory and Vestibular Pathways." Bioon. Web. 31 Mar. 2014. <http://www.bioon.com/bioline/neurosci/course/audvest.html>. "Auditory Tube - Ear." Inner Body. Human Anatomy. Web. 31 Mar. 2014. <http://www.innerbody.com/image_nerv13/nerv128-new.html>. "Ear Anatomy." Enchanted Learning. Web. 31 Mar. 2014. <http://www.enchantedlearning.com/subjects/anatomy/ear/>. "The Human Ear." Biology of Humans. Pearson, Web. 31 Mar. 2014. <http://wps.aw.com/bc_goodenough_boh_4/177/45511/11650899.cw/index.html>. "Structure of the Ear." Visual Meriam Dictionary. Meriam-Webster, Web. 31 Mar. 2014. <http://visual.merriam-webster.com/human-being/sense-organs/hearing/structure-ear.php>. Wedro, Benjamin C., M.D. "Hearing and Balance Anatomy." Ed. William C. Shiel, M.D. Medicine Net. Web. 31 Mar. 2014. <http://www.medicinenet.com/script/main/art.asp?articlekey=21685>.

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