Anatomy
Stanley A. Gelfand in Hearing, 2017
The auditory (or cochlear) nerve appears as a twisted trunk, its core made up of fibers derived from the apex of the cochlea and its outer layers coming from more basal regions. The nerve leaves the inner ear via the internal auditory meatus, and enters the brainstem at the lateral aspect of the lower pons. We are now in the central auditory nervous system, or the central auditory pathways, the major aspects of which are outlined in this section. Although not addressed here, interested students will find a summary of the neurotransmitters associated with the auditory system in Table 2.2. In addition, many sources are available to those wishing to pursue a more detailed coverage of the anatomy and physiology of the auditory pathways (e.g., Moore, 1987; Popper and Fay, 1992; Webster et al., 1992; Winer, 1992; Ehret and Romand, 1997; Møller, 2000; Moore and Linthicum, 2003; Musiek and Baran, 2007; Palmer, 2007; Winer and Lee, 2007).
ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
The auditory pathways begin with the transduction of sound into neural impulses in the COCHLEA. From the cochlea, the COCHLEA NERVE (also known as the AUDITORY NERVE and, with the VESTIBULAR NERVE, one of the principal branches of the VESTIBULOCOCHLEAR NERVE [the eighth cranial nerve]) travels to the COCHLEAR NUCLEUS in the pons via the COCHLEA NERVE GANGLION. The cochlear nerve ganglion contains BIPOLAR NEURONS: one limb receives information from the cochlea; then other limb transmits to the cochlear nucleus. This ganglion is also known as the SPIRAL GANGLION, its shape reflecting that of the cochlea itself. The auditory pathway so far is organized entirely ipsilaterally. At the level of the cochlear nucleus there is crossing of information to enable binaural perception of sound: the anteroventral and posteroventral portions of the cochlear nucleus project ipsilaterally and contralaterally to the SUPERIOR OLIVARY COMPLEX. The dorsal cochlear nucleus projects contralaterally to the INFERIOR COLLICULUS.
Domain III: Communication
Nicole M. Augustine in Prevention Specialist Exam Study Guide, 2023
It is important to understand the difference between listening and hearing. Hearing is the physiological process of sound waves being transformed into auditory nerve impulses (Hogan, 2003, p. 236). The process of listening is not the same as hearing; it requires paying close attention to what is being said and making sense of the information that has been received. The brain is a powerful organ in the human body and is capable of processing information quickly. Your brain can understand up to 400 words per minute. However, people only speak about 125–150 words per minute (Hogan, 2003, p. 237). This gap creates space for the receiver to be distracted by noise, and loss of attention minimizes clear understanding. Listening for understanding is truly an accomplished skill, which is why it is said ‘the best leaders are great listeners.’ Listening requires discipline of the mind, and once you understand this concept, you can translate this knowledge into making you a better overall communicator; sender and receiver.
Sound localisation of low- and high-frequency sounds in cochlear implant users with single-sided deafness
Published in International Journal of Audiology, 2023
J. Seebacher, A. Franke-Trieger, V. Weichbold, O. Galvan, J. Schmutzhard, P. Zorowka, K. Stephan
The reason for the improvement in sound localisation when patients with SSD are given a CI in their deaf ear is not yet fully understood. The acoustic information is delivered to the auditory system via two distinctly different pathways: in one ear via normal (acoustic) hearing and on the other side via direct electrical stimulation of the cochlear nerve. Two different inputs (acoustic and electric signals) have to be combined along the auditory pathway in order to evaluate ITDs and ILDs of incident sound. Coding of these cues relevant for localisation of sounds is not primarily considered in today’s CI coding strategies. Originally, the primary focus of development was to improve speech perception, followed by the sound quality. Typically, signal processing in CI is optimised to encode the envelope of the acoustic signal. Fundamental observations were made by Shannon and colleagues, who found that envelope coding of a few tonotopically arrayed frequency bands was already sufficient for speech recognition in patients with CI (Dillon et al. 2016). Current processing strategies further attempt to encode the low-frequency acoustic fine structure information of sound, which could also be used for localisation issues.
Vestibular nerve deficiency and vestibular function in children with unilateral hearing loss caused by cochlear nerve deficiency
Published in Acta Oto-Laryngologica, 2021
Keita Tsukada, Shin-ichi Usami
Recently, advances in diagnostic imaging technology have made it possible to diagnose CND, which has been recognized as a cause of SNHL[1,2]. It is proposed that CND results from developmental disorders in the embryonic stage and/or inner ear neuropathy in the early post-natal period [2]. The inner ear nerves consist of the cochlear nerve, and the upper and lower vestibular nerves. Based on the possibility of a developmental disorder, not only CND but also VND is expected. However, there have been few reports to date focusing on VND. McClay reported that hypoplasia or an absence of the vestibular nerve was observed in 12 of 49 ears (24%) with CND [3], and Adunka also reported that a loss of vestibular nerve was observed in 11 of 20 (55%) ears in CND cases [7]. In the present study, 36.8% of patients showed a vestibular nerve that was absent or smaller than that on the contralateral side (Figure 2(a)), suggesting that majority of the cases had only cochlear nerve deficiencies without VND.
Adam Politzer (1835-1920) and the cochlear nucleus
Published in Journal of the History of the Neurosciences, 2021
Albert Mudry, John Riddington Young
Politzer had also described the histology in an anatomy textbook: The histological examination of the transverse sections of the medulla oblongata to ascertain the topographical relations of the acusticus and its nuclei is of great importance to the otologist, as it is only by the knowledge of the complicated relations of the central course of the nerve that he will be able to judge the congenital anomalies and arrested development in the central area of origin of this nerve, and of primary and secondary pathological changes which occur there. … The examination of the acusticus nuclei and the course of its fibres in the central nervous system, requires special staining techniques. … A transverse section through the medulla oblongata in the lowest plane of the acusticus … shows that this nerve occupies the outer area of the oblongata … as the inner portion of the pedonculus cerebelli, but assigned by Freud to the acusticus, known as Deiters’ nucleus. In the outer central corner of the section lies a large nucleus of the auditory nerve [Kern des Hörnerven], the anterior or external nucleus. (Politzer 1889, 237–39)
Related Knowledge Centers
- Axon
- Bipolar Neuron
- Cochlea
- Inner Ear
- Semicircular Canals
- Vestibular Nerve
- Vestibulocochlear Nerve
- Brain
- Cranial Nerves
- Unipolar Neuron