![]() ![]() By regulating arteriole diameter, the vessel-associated component has a significant effect on CBF. Sympathetic innervation influences vascular tone. The regulation of CBF by the sympathetic nervous system and ARs is well established. The blood supply to the cochlea originates from the common cochlear artery, which includes the spiral modiolar and vestibulocochlear arteries. The functional significance of cochlear adrenergic innervation includes its roles in the regulation of blood flow volume, and in the control the metabolism of inner hair cells (IHCs), and outer hair cells, as well as efferent and afferent axons. The sympathetic nervous system projecting into the inner ear comprises 2 main components : a vessel-associated component originating from the SG bilaterally and a dense plexus forming around the major arteries, and a vessel-independent component originating ipsilaterally from the SCG producing multiple terminals in the osseous spiral lamina region, which contains the cell bodies and axons of cochlear nerve fibers. Tyrosine-hydroxylase-immunoreactive nerve fibers are expressed in most regions of the middle ear mucosa, and these fibers are close to small-caliber vessels. In mammals, the peripheral auditory system receives extensive adrenergic innervation from the sympathetic nervous system, particularly from the superior cervical ganglia (SCG) and stellate ganglion (SG). 1) consists of the external ear, middle ear, inner ear, and auditory nerve. The peripheral auditory system (shown in Fig. For example, a mechanism was reported that demonstrated a vessel associated with sympathetic led to cochlear vasoconstriction and exacerbated noise-induced cochlear damage. Understanding this relationship is of high clinical significance. Modulation of the auditory system by the sympathetic nervous system is complex. In pathological states, dysfunction of the sympathetic nervous system may lead to auditory disorders. Centrally, the key roles of locus coeruleus (LC)-NE on auditory pathways are predominantly inhibitory. In the periphery, sympathetic nerves mainly regulate cochlear blood flow (CBF). The regulation of peripheral and central auditory pathways by the sympathetic nervous system has been reported. The ARs are widely present across the peripheral and central auditory pathways (shown in Table 1) and are positioned to affect auditory and vestibular processing. These ARs belong to the G protein-coupled receptor superfamily. ![]() Adrenergic receptors (ARs) regulate the functional effects of NE and adrenaline. Sympathetic nerve postganglionic fiber neurotransmitters predominantly comprise norepinephrine (NE), adrenaline, acetylcholine, purine, and polypeptides. Sympathetic efferent pathways form a component of the autonomic nervous system. The mechanisms and pathways of sympathetic nervous system modulation of auditory function is still valuable for us to research and discuss. In pathological states, the sympathetic nervous system is associated with many hearing disorders. ![]() In central auditory pathways, norepinephrine is essential for plasticity in the auditory cortex and affects auditory cortex activity. Key Messages: In the peripheral auditory system, the sympathetic nervous system regulates cochlear blood flow, modulates cochlear efferent fibers, affects hair cells, and influences the habenula region. Herein, we review the distribution and putative physiological and pathological roles of sympathetic nervous system projections in hearing. Summary: As such, understanding sympathetic nervous system regulation of auditory function is a growing topic of interest. With the rapid development of neuroscience, auditory central regulation is an extant topic of focus in research on hearing. Nevertheless, research on adrenergic and noradrenergic regulation of the cochlea and central auditory system is growing. The function of sympathetic fibers in the cochlea has not been studied extensively due to the limited number of direct projections in the auditory system. Sympathetic nervous system projections are present throughout the auditory system. It comprises both peripheral and central structures. ![]() Background: The auditory system processes how we hear and understand sounds within the environment. ![]()
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