The Ear Houses two senses 1 Hearing 2

The Ear § Houses two senses 1) Hearing 2) Equilibrium (balance) § Mechanoreceptors – receptors that respond to physical forces; both respond to movements of fluid § Different organs house receptors for each sense and are independent of each other.

Anatomy of the Ear § The ear is divided into three areas 1) Outer (external) ear 2) Middle ear 3) Inner ear Figure 8. 12

The External Ear § Involved in hearing only § Structures of the external ear 1) Pinna (auricle) 2) External auditory canal Figure 8. 12

The External Auditory Canal § Narrow chamber in the temporal bone § Lined with skin § Ceruminous (wax) glands are present § https: //www. youtube. com/watch? v=QJV 0 COt. SPdo § https: //www. youtube. com/watch? v=QHOX 1 R 5 b 770 § Ends at the tympanic membrane

The Middle Ear or Tympanic Cavity § Air-filled cavity within the temporal bone § Only involved in the sense of hearing

The Middle Ear or Tympanic Cavity § Tympanic membrane (Eardrum) – Skin covering the opening of the middle ear; stretched tight to sense vibrations like a drum head. § Auditory tube connects the middle ear with the throat § Allows for equalizing pressure during yawning or swallowing; otherwise this tube is collapsed

The Middle Ear or Tympanic Cavity § Homeostatic Imbalance § Otitis Media (Ear Infection) – inflammation of the middle ear. § Symptoms: eardrum bulges from large amounts of fluid in the cavity as it fights the infection. The pressure causes pain and can rupture the eardrum § Tubes can be placed in the eardrum so that the fluids drain to relieve pressure

The Middle Ear or Tympanic Cavity § Homeostatic Imbalance: Otitis media continued § Usually results from bacteria infection in the throat area; sore throat. § Problem in small children whose auditory tube runs more horizontal § Don’t “prop” a bottle or feed a baby lying flat because it can enter the tube § http: //www. youtube. com/watch? v=T 8 g 62 Fygepg

Bones of the Tympanic Cavity § Three bones span the cavity § Malleus (hammer) § Incus (anvil) § Stapes (stirrup) Figure 8. 12

Bones of the Tympanic Cavity § Vibrations from eardrum move the malleus § These bones transfer sound to the inner ear § If you have problems with these bones … you don’t hear!! Figure 8. 12

Inner Ear or Bony Labyrinth § Includes sense organs for hearing and balance § Filled with perilymph which is a plasma-like fluid Figure 8. 12

Inner Ear or Bony Labrynth § A maze of bony chambers within the temporal bone § 3 subdivisions of the Inner Ear 1) Cochlea 2) Vestibule 3) Semicircular canals Figure 8. 12