autonomic plexus

Examples of autonomic plexus in the following topics:

• Autonomic Plexuses

  • Autonomic plexuses are formed from sympathetic and parasympathetic fibers that innervate and regulate the overall activity of visceral organs.
  • Autonomic plexuses are formed from sympathetic postganglionic axons, parasympathetic preganglionic axons, and some visceral sensory axons.
  • The autonomic plexuses include the cardiac plexus, the pulmonary plexus, the esophageal plexus, and abdominal aortic plexus, and the superior and inferior hypogastric plexuses.
  • The pulmonary plexus is an autonomic plexus formed from pulmonary branches of vagus nerve and the sympathetic trunk.
  • The esophageal plexus and the cardiac plexus contain the same types of fibers and are both considered thoracic autonomic plexus(es).

• Plexuses

  • There are five spinal nerve plexuses—except in the thoracic region—as well as other forms of autonomic plexuses, many of which are a part of the enteric nervous system.
  • The plexus extends toward the armpit (axilla).
  • The lumbar plexus is formed by the ventral rami of L1–L5 spinal nerves with a contribution of T12 form the lumbar plexus.
  • This plexus lies within the psoas major muscle.
  • In addition, the celiac plexus serves the internal organs, and Auerbach's plexus serves the gastrointestinal tract.

• Function and Physiology of the Spinal Nerves

  • The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system.
  • The term spinal nerve generally refers to a mixed spinal nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body.
  • The last four cervical spinal nerves, C5 through C8, and the first thoracic spinal nerve, T1, combine to form the brachial plexus, or plexus brachialis, a tangled array of nerves, splitting, combining and recombining to form the nerves that subserve the upper limb region and upper back.
  • Although the brachial plexus may appear tangled, it is highly organized and predictable with little variation among people.
  • For descriptive purposes, this plexus is usually divided into three parts: lumbar plexus, sacral plexus, and pudendal plexus.

• Overview of the Spinal Nerves

  • Spinal nerves, a part of the peripheral nervous system (PNS), are mixed nerves that send motor, sensory, and autonomic signals between the CNS and the body.
  • The term spinal nerve generally refers to a mixed spinal nerve that carries motor, sensory, and autonomic signals between the spinal cord and the body.
  • The anterior distribution includes the cervical plexus (C1–C4) and brachial plexus (C5–T1).
  • A loop of nerves called ansa cervicalis is also part of the cervical plexus.
  • Its anterior root helps form the coccygeal plexus.

• Enteric Nervous System

  • The ENS is capable of autonomous functions such as the coordination of reflexes.
  • The myenteric plexus is mainly organized as a longitudinal chains of neurons.
  • This plexus is concerned with motility throughout the whole gut.
  • The mucosa and epithelial tissue associated with the submucosal plexus have sensory nerve endings that feed signals to both layers of the enteric plexus.
  • For instance, the enteric nervous system can operate autonomously.

• Autonomic Nervous System (ANS)

  • The autonomic nervous system is a part of the peripheral nervous system that controls visceral functions such as heart rate and digestion.
  • These have been found to be integral in autonomic function, particularly in the gut and the lungs.
  • The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system.
  • Some have their cell bodies in the enteric plexus, and some in the spinal cord.
  • An illustration of neural control of the gut wall by the autonomic nervous system and the enteric nervous system.

• Branches of Spinal Nerves

  • Some ventral rami merge with adjacent ventral rami to form a nerve plexus, a network of interconnecting nerves.
  • Nerves emerging from a plexus contain fibers from various spinal nerves, which are now carried together to some target location.
  • The rami communicantes: Contain autonomic nerves that carry visceral motor and sensory information to and from the visceral organs.

• Sacral and Coccygeal Plexuses

  • The sacral plexus is the plexus of the three sacral spinal nerves (S2–S4) that arise from the lower back just above the sacrum.
  • The sacral plexus is a nerve plexus that provides motor and sensory nerves for the posterior thigh, most of the lower leg, the entire foot, and part of the pelvis.
  • Often, the sacral plexus and the lumbar plexus are considered to be one large nerve plexus, the lumbosacral plexus.
  • The coccygeal plexus originates from the S4, S5, and Co1 spinal nerves.
  • It is interconnected with the lower part of the sacral plexus.

• Intercostal Nerves

  • They differ from the anterior divisions of the other spinal nerves in that each pursues an independent course without plexus formation.
  • The larger branch leaves the thorax in front of the neck of the first rib and enters the brachial plexus.
  • The branch from the second nerve unites with the anterior supraclavicular nerves of the cervical plexus.
  • Unlike the nerves from the autonomic nervous system that innervate the visceral pleura of the thoracic cavity, the intercostal nerves arise from the somatic nervous system.

• Brachial Plexus

  • The brachial plexus is formed by the four lower cervical spinal nerves and the first thoracic spinal nerve.
  • The brachial plexus proceeds through the neck, the axilla (armpit region), and into the arm.
  • Lesions on the brachial plexus can lead to severe functional impairment.
  • The brachial plexus is divided into roots, trunks, divisions, cords, and branches.
  • The right brachial plexus with its short branches, viewed from the front.