the effectors of the somatic nervous system are

THE EFFECTORS OF THE SOMATIC NERVOUS SYSTEM ARE MANUAL

The neurotransmitters that mediate transmission from sensory fibers have not been characterized unequivocally.

Those concerned with muscle chemosensation may arise at all spinal levels, whereas sympathetic visceral sensory afferents generally arise at the thoracic levels where sympathetic preganglionic neurons are found. Sensory afferents from visceral organs also enter the CNS from the spinal nerves and convey information concerned with temperature as well as nociceptive visceral inputs related to mechanical, chemical, and thermal stimulation.

The visceral afferents from these 4 cranial nerves terminate topographically in the solitary tract nucleus. The pelvic viscera are innervated by nerves from the second through fourth sacral spinal segments. These 4 cranial nerves transmit visceral sensory information from the internal face and head (V) tongue (taste, VII) hard palate and upper part of the oropharynx (IX) and carotid body, lower part of the oropharynx, larynx, trachea, esophagus, and thoracic and abdominal organs (X), with the exception of the pelvic viscera. The cranial visceral sensory system carries mainly mechanoreceptor and chemosensory information, whereas the afferents of the spinal visceral system principally convey sensations related to temperature and tissue injury of mechanical, chemical, or thermal origin.Ĭranial visceral sensory information enters the CNS by 4 cranial nerves: the trigeminal (V), facial (VII), glossopharyngeal (IX), and vagus (X) nerves. Information on the status of the visceral organs is transmitted to the CNS through 2 main sensory systems: the cranial nerve (parasympathetic) visceral sensory system and the spinal (sympathetic) visceral afferent system. With certain exceptions, such as local axon reflexes, most visceral reflexes are mediated through the central nervous system (CNS). VISCERAL AFFERENT FIBERS. The afferent fibers from visceral structures are the first link in the reflex arcs of the autonomic system.

When the spinal efferent nerves are interrupted, smooth muscles and glands generally retain some level of spontaneous activity, whereas the denervated skeletal muscles are paralyzed.

Postganglionic autonomic nerves generally are nonmyelinated motor nerves to skeletal muscles are myelinated.

Many autonomic nerves form extensive peripheral plexuses such networks are absent from the somatic system.

Somatic nerves contain no peripheral ganglia, and the synapses are located entirely within the cerebrospinal axis. The most distal synaptic junctions in the autonomic reflex arc occur in ganglia that are entirely outside the cerebrospinal axis.The efferent nerves of the ANS supply all innervated structures of the body except skeletal muscle, which is served by somatic nerves.In the periphery, it consists of nerves, ganglia, and plexuses that innervate the heart, blood vessels, glands, other visceral organs, and smooth muscle in various tissues.ĭIFFERENCES BETWEEN AUTONOMIC AND SOMATIC NERVES the visceral, vegetative, or involuntary nervous system) regulates autonomic functions that occur without conscious control. Neurotransmission: The Autonomic and Somatic Motor Nervous Systems

THE EFFECTORS OF THE SOMATIC NERVOUS SYSTEM ARE MANUAL

Goodman and Gilman Manual of Pharmacology and Therapeutics Section II

The effectors of the somatic nervous system are