sacral plexus

Examples of sacral plexus in the following topics:

• 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.
  • It is part of the lumbosacral plexus and emerges from the sacral vertebrae (S2–S4).
  • Often, the sacral plexus and the lumbar plexus are considered to be one large nerve plexus, the lumbosacral plexus.
  • It is interconnected with the lower part of the sacral plexus.
  • Diagram of the sacral plexus showing the various anterior and posterior nerve branches that arise from each lumbar and sacral nerve.

• Plexuses

  • 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.
  • The sacral plexus is formed by the ventral rami of L4-S3, with parts of the L4 and S4 spinal nerves.
  • It is interconnected with the lower part of sacral plexus.
  • In addition, the celiac plexus serves the internal organs, and Auerbach's plexus serves the gastrointestinal tract.

• Function and Physiology of the Spinal Nerves

  • Each pair of spinal nerves roughly correspond to a segment of the vertebral column: 8 cervical spinal nerve pairs (C1–C8), 12 thoracic pairs (T1–T12), 5 lumbar pairs (L1–L5), 5 sacral pairs (S1–S5), and 1 coccygeal pair.
  • 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.
  • The anterior divisions of the lumbar, sacral, and coccygeal nerves form the lumbosacral plexus, the first lumbar nerve being frequently joined by a branch from the twelfth thoracic.
  • For descriptive purposes, this plexus is usually divided into three parts: lumbar plexus, sacral plexus, and pudendal plexus.

• Overview of the Spinal Nerves

  • 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.
  • The smaller part of the fourth joins with the fifth to form the lumbosacral trunk, which assists in the formation of the sacral plexus.
  • Each nerve emerges in two divisions: one division through the anterior sacral foramina and the other division through the posterior sacral foramina.
  • Its anterior root helps form the coccygeal plexus.

• 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.
  • Major plexuses include the cervical, brachial, lumbar, and sacral plexuses.

• Autonomic Plexuses

  • 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 cardiac plexus is a plexus of nerves situated at the base of the heart that innervates the heart.
  • 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).
  • The inferior hypogastric plexus (pelvic plexus in some texts) is a plexus of nerves that supplies the viscera of the pelvic cavity.

• 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.

• Injuries to Nerves Emerging from the Brachial Plexus

  • Brachial plexus injuries, or lesions, are caused by damage to those nerves.
  • But in general, brachial plexus lesions can be classified as either traumatic or obstetric.
  • The brachial plexus may be injured by falls from a height on to the side of the head and shoulder, whereby the nerves of the plexus are violently stretched.
  • Cervical (C5-C8) and thoracic (T1) comprise the brachial plexus, which is a nerve plexus that provides sensory and motor function to the shoulders and upper limbs.
  • Describe the effects of injuries to the nerves of the brachial plexus

• Autonomic Nervous System (ANS)

  • The distal half is innervated via the Sacral Parasympathetic nerves.
  • Some have their cell bodies in the enteric plexus, and some in the spinal cord.

• Cervical Plexus

  • The cervical plexus is the plexus of the ventral rami of the first four cervical spinal nerves.
  • The cervical plexus is a plexus of the ventral rami of the first four cervical spinal nerves located from the C1 to C4 cervical segment in the neck.
  • Nerves formed from the cervical plexus innervate the back of the head, as well as some neck muscles.
  • The cervical plexus has two types of branches: cutaneous and muscular.
  • The great auricular nerve originates from the cervical plexus and is composed of branches from spinal nerves C2 and C3.