Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Fundamentals of Anatomy & Physiology SIXTH EDITION Frederic H. Martini PowerPoint ® Lecture Slide Presentation prepared by Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii Chapter 17, part 3 The Special Senses
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings SECTION 17-4 Equilibrium and Hearing
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of the ear – External Ear Auricle or pinnae surrounds the ear External acoustic meatus ends on tympanic membrane Both equilibrium and hearing are provided by receptors of the inner ear
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure The Anatomy of the Ear
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Communicates with pharynx via pharyngotympanic membrane Middle ear encloses and protects the auditory ossicles Middle ear
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure The Middle Ear
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Membranous labyrinth contains endolymph Bony labyrinth surrounds and protects membranous labyrinth Vestibule Semicircular canals Cochlea Inner ear
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure The Inner Ear
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Vestibule contains the utricle and saccule Semicircular canals contain the semicircular ducts Cochlea contains the cochlear duct Components of the inner ear
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Round window separates the perilymph from the air spaces of the middle ear Oval window connected to the base of the stapes Basic receptors of inner ear are hair cells Provide information about the direction and strength of stimuli Windows
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Anterior, posterior and lateral semicircular ducts are continuous with the utricle Each duct contains an ampulla with a gelatinous cupula and associated sensory receptor Saccule and utricle connected by a passageway continuous with the endolymphatic duct Terminates in the endolymphatic sac Saccule and utricle have hair cells clustered in maculae Cilia contact the otolith (statoconia) Equilibrium
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17.23a, b, & d Figure The Vestibular Complex
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17.23c Figure The Vestibular Complex
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17.23e Figure The Vestibular Complex
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Vestibular receptors activate sensory neurons of the vestibular ganglia Axons form the vestibular branch of cranial nerve VII Synapses within the vestibular nuclei Vestibular neural pathway
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure Pathways for Equilibrium Sensation
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cochlear duct lies between the vestibular duct and the tympanic duct Hair cells of the cochlear duct lie within the Organ of Corti Intensity is the energy content of a sound Measured in decibels Hearing
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17.25a, b Figure The Cochlea
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17.26a, b Figure The Organ Of Corti
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Sound waves travel toward tympanic membrane, which vibrates Auditory ossicles conduct the vibration into the inner ear Tensor tympani and stapedius muscles contract to reduce the amount of movement when loud sounds arrive Movement at the oval window applies pressure to the perilymph of the cochlear duct Pressure waves distort basilar membrane Hair cells of the Organ of Corti are pushed against the tectoral membrane Pathway of sound
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 17.28a Figure Sound and Hearing
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure Figure Sound and Hearing
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Neural pathway Sensory neurons of hearing are located in the spiral ganglion of the cochlea Afferent fibers form the cochlear branch of cranial nerve VIII Synapse at the cochlear nucleus
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings You should now be familiar with: The sensory organs of smell, and the olfactory pathways in the brain. The accessory and internal structures of the eye, and their functions. How light stimulates the production of nerve impulses, and the visual pathways. The structures of the external and middle ear and how they function. The parts of the inner ear and their roles in equilibrium and hearing. The pathways for the sensations of equilibrium and hearing.