Ebook Lippincott’s illustrated review of neuroscience: Part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Ebook Lippincott’s illustrated review of neuroscience: Part 2
Ebook Lippincott’s illustrated review of neuroscience: Part 2
Hearing and BalanceI. OVERVIEWBoth hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerve Ebook Lippincott’s illustrated review of neuroscience: Part 2e (cranial nerve [CN] VIII).The sensory organs and the peripheral ganglia associated with CN VIII are located in the petrous part of the temporal bone in the base of the skull (Figure 11.1). The labyrinth is specialized to translate motion of the head into information about balance, and the afferent Ebook Lippincott’s illustrated review of neuroscience: Part 2s from the labyrinth that carry balance information are bundled together as the vestibular division. The afferents from the cochlea, which carry soundEbook Lippincott’s illustrated review of neuroscience: Part 2
information, are bundled together as the cochlear division. Both divisions come together as the vestibulocochlear nerve, which travels from the recepHearing and BalanceI. OVERVIEWBoth hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerve Ebook Lippincott’s illustrated review of neuroscience: Part 2stem at the pontomedullary junction (Figure 11.2).Hearing and balance are two very different types of senses. Both the cochlear (hearing) and vestibular (balance) divisions of CN VIII receive stimuli from specialized end organs that contain mechanoreceptors calledFigure 11.1Position of the inner ear Ebook Lippincott’s illustrated review of neuroscience: Part 2 in the temporal bone of the skull.19920011. Hearing and BalanceFigure 11.2The vestibulocochlear nerve at the pon-tomedullary junction ot the brainsteEbook Lippincott’s illustrated review of neuroscience: Part 2
m. CN = cranial nerve."hair coils' because of their appearance. Although similar in appearance. hair cells respond to different stimuli. They respond Hearing and BalanceI. OVERVIEWBoth hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerve Ebook Lippincott’s illustrated review of neuroscience: Part 2s are interpreted in terms of their pitch, loudness. and their location of origin. The human ear has the remarkable capability to distinguish a large range of sounds that can be either very close together in pitch (maybe just a quarter note apart) or far apart in pitch (ranging from the low rumbling Ebook Lippincott’s illustrated review of neuroscience: Part 2s of a pipe organ to the highest notes of a piccolo flute).Hearing is an integral component of communication. The sounds of speech are perceived and tEbook Lippincott’s illustrated review of neuroscience: Part 2
hen relayed to higher centers where they are reassembled to make sense as words and phrases.A. Structures involved in hearingThe structures involved iHearing and BalanceI. OVERVIEWBoth hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerve Ebook Lippincott’s illustrated review of neuroscience: Part 2ollect sound waves and focus them onto the tympanic membrane, which separates the outer ear from the middle ear. The middle ear is an air-filled space, which contains three small bones that amplify the sound energy from the tympanic membrane to the fluid-filled inner ear. The inner ear contains the Ebook Lippincott’s illustrated review of neuroscience: Part 2cochlea, which contains the sensory organ of hearing, the organ of Corti.1.Outer ear: The outer ear IS the visible part of the ear on the side of theEbook Lippincott’s illustrated review of neuroscience: Part 2
head. It is composed of the auricle and the external auditory meatus, or outer ear canal. These structures gather sound energy and focus this energy oHearing and BalanceI. OVERVIEWBoth hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerve Ebook Lippincott’s illustrated review of neuroscience: Part 2reflects sound, causing it to reach the tympanic membrane in a time-delayed manner. This plays a role in sound localization, as is discussed below.The external auditory meatus also plays a role in how sound waves are transmitted to the middle ear. Sound pressure at frequencies around 3 kHz (the freq Ebook Lippincott’s illustrated review of neuroscience: Part 2uency to which the human ear is most sensitive) is boosted in the external auditory meatus through passive resonance effects (echo).2.Middle ear: TheEbook Lippincott’s illustrated review of neuroscience: Part 2
middle ear is located between the tympanic membrane and the inner ear. It is an air-filled chamber that contains three small bones, or ossicles, that Hearing and BalanceI. OVERVIEWBoth hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerve Ebook Lippincott’s illustrated review of neuroscience: Part 2(Eustachian) tube (see Figure 11.3). This connection is important to ensure that air pressure in the middle ear corresponds to the air pressure around us. The pharyngotympanic tube opens to let air into the middle ear and equilibrate the pressure (for example, during a plane landing when the ears “p Ebook Lippincott’s illustrated review of neuroscience: Part 2op”).II. Hearing201Figure 11.3Overview of structures of the outer, middle, and inner ear.a.Bones in the middle ear: The ossicles in the middle ear areEbook Lippincott’s illustrated review of neuroscience: Part 2
the malleus, the incus, and the stapes. The malleus is directly attached to the tympanic membrane. The malleus articulates with the incus, which is cHearing and BalanceI. OVERVIEWBoth hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerve Ebook Lippincott’s illustrated review of neuroscience: Part 2to boost the sound energy from the tympanic membrane into the inner ear. This boost is necessary so that the sound waves traveling through the air can be transferred efficiently to the fluid-filled space of the inner ear. Without a boost, the sound energy would be lost through reflection once the so Ebook Lippincott’s illustrated review of neuroscience: Part 2und waves hit fluid. The boost is achieved through the lever action of the ossicles as well as through compression of sound waves from the large-diameEbook Lippincott’s illustrated review of neuroscience: Part 2
tor tympanic membrane to the small-diameter oval window.b.Muscles in the middle ear: The middle oar also contains two muscles: the tensor tympani, whiHearing and BalanceI. OVERVIEWBoth hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerve Ebook Lippincott’s illustrated review of neuroscience: Part 2of the stapedius muscle can reduce the transmission of vibration into the inner ear, especially for low-frequency sounds, possibly to selectively filter out low-frequency background noises. These two muscles also dampen movements of the ossicles in response to loud sounds, which serves as a protecti Ebook Lippincott’s illustrated review of neuroscience: Part 2ve mechanism for the auditory nerve.3.Inner ear: The inner ear contains the cochlea, the sensory organ that mediates the transformation of the pressurEbook Lippincott’s illustrated review of neuroscience: Part 2
e waves of sound into the electrical energy of a nerve impulse (Figure 11.4).a. Cochlea: The cochlea sits in the petrous portion of the temporal bone,Hearing and BalanceI. OVERVIEWBoth hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerveHearing and BalanceI. OVERVIEWBoth hearing and balance are sensations carried by special somatic afferent fibers that form the vestibulocochlear nerveGọi ngay
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