![]() ![]() The various nerve fibers and cells that make up the autonomic nervous system innervate the glands, heart, blood vessels, and involuntary muscles of the internal organs. Spinal nerves arise from the spinal cord and pass out between the vertebrae there are 31 pairs, 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. There are 12 pairs of cranial nerves, which carry messages to and from the brain. Sensorineural hearing loss (SNHL) or nerve deafness can be defined as a type of hearing impairment that is caused due to dysfunction of the sensory receptors present in the inner ear. Together, the nerves make up the peripheral nervous system, as distinguished from the central nervous system (brain and spinal cord). Sound waves enter the outer ear (the pinna) and are sent to the eardrum via the auditory canal. The hearing system is designed to assess frequency (pitch) and amplitude (loudness). Mixed nerves are composed of both motor and sensory fibers, and transmit messages in both directions at once. Place theory of hearing is unable to account for sounds with very low frequencies, such as those in bass notes, due to the fact that there are no auditory nerve fibers that have a preference for. Sound waves vibrating through media such as air, water, or metal are the stimulus energy that is sensed by the ear. Motor nerves, or efferent nerves, transmit impulses from the brain and spinal cord to the muscles. Sensory nerves, sometimes called afferent nerves, carry information from the outside world, such as sensations of heat, cold, and pain, to the brain and spinal cord. See Appendix 2-6 and see color plates.ĭepending on their function, nerves are known as sensory, motor, or mixed. A macroscopic cordlike structure of the body, comprising a collection of nerve fibers that convey impulses between a part of the central nervous system and some other body region. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |