9808 Lecture Notes - Lecture 15: Stapes, Stapedius Muscle, Low Frequency

• School: University of Canberra
• Department: University of Canberra
• Course: 9808
• Professor: Julie Cooke

Document Summary

Lecture 15 special senses: hearing and equilibrium. Sound is pressure waves and we have receptors for picking changes in pressure. For hearing and equilibrium receptors are hair cells which act as mechanoreceptors. Tympanic membrane (sound waves terminate here): thin connective tissue membrane that vibrates when pressure waves hit it. Malleus, incus, stapes (smallest bones) moves when sound gets to it and puts pressure on window (connective tissue layer which is entrance into cochlear duct). Oval window is opening to cochlea duct filled with fluid, therefore fluid pressure wave when stapes pulls on it in cochlea. Auditory tube allows equalization of pressure (normally enclosed) When it rocks it vibrates on window which vibrates fluid within bony labyrinth. With really loud sounds we can damage tympanic membrane and oval window - we have dampening muscles (tensor tympanic and stapedius) and when they contract it limits movement of tympanic membrane.