nerve plexus

Examples of nerve 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.
  • 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.
  • The only nerve in this plexus is the anococcygeal nerve, which serves sensory innervation of the skin in the coccygeal region.

• Plexuses

  • A nerve plexus is a network of intersecting nerves  that serve the same part of the body.
  • A nerve plexus is a network of intersecting nerves; multiple nerve plexuses exist in the body.
  • The lumbar plexus is formed by the ventral rami of L1–L5 spinal nerves with a contribution of T12 form the lumbar plexus.
  • The lumbar plexus is comprised of the ventral rami of the lumbar spinal nerves (L1–L5) and a contribution from thoracic nerve (T12).
  • Cervical (C5–C8) and thoracic (T1) nerves comprise the brachial plexus, which is a nerve plexus that provides sensory and motor function to the shoulders and upper limbs.

• Injuries to Nerves Emerging from the Brachial Plexus

  • Lesions in nerves of the brachial plexus are classified as obstetric or traumatic as a result of shoulder trauma, inflammation, or tumors.
  • Brachial plexus injuries, or lesions, are caused by damage to those nerves.
  • 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 Plexuses

  • Cardiac: The cardiac plexus is a plexus of nerves situated at the base of the heart that innervates the heart.
  • Pulmonary: The pulmonary plexus is an autonomic plexus formed from pulmonary branches of vagus nerve and the sympathetic trunk.
  • Esophageal: The esophageal plexus is formed by nerve fibers from two sources: branches of the vagus nerve and visceral branches of the sympathetic trunk.
  • Superior hypogastric plexus: The superior hypogastric plexus (in older texts, hypogastric plexus or presacral nerve) is a plexus of nerves situated on the vertebral bodies below the bifurcation of the abdominal aorta.
  • Inferior hypogastric plexus: The inferior hypogastric plexus (pelvic plexus in some texts) is a plexus of nerves that supplies the viscera of the pelvic cavity.

• Branches of Spinal Nerves

  • The spinal nerves branch into the dorsal ramus, ventral ramus, the meningeal branches, and the rami communicantes.
  • 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 meningeal branches (recurrent meningeal or sinuvertebral nerves): These branch from the spinal nerve and re-enter the intervertebral foramen to serve the ligaments, dura, blood vessels, intervertebral discs, facet joints, and periosteum of the vertebrae.
  • This diagram depicts the course and branches of a typical thoracic spinal nerve.

• Lumbar Plexus

  • The lumbar plexus is formed by the subcostal nerve and divisions of the first four lumbar nerves that arise from the middle to lower back.
  • The lumbar plexus is a nerve plexus in the lumbar region of the body that forms part of the lumbosacral plexus.
  • The largest nerve of the plexus is the femoral nerve and it supplies the anterior muscles of the thigh and a part of skin distal to the inguinal ligament.
  • Femoral nerve: This is the largest and longest of the plexus' nerves.
  • An image of the lumbar plexus with its nerves highlighted in yellow.

• 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 branches of the cervical plexus emerge from the posterior triangle at the nerve point, a point that lies midway on the posterior border of the sternocleidomastoid.
  • The great auricular nerve originates from the cervical plexus and is composed of branches from spinal nerves C2 and C3.

• Brachial Plexus

  • The brachial plexus is formed by the four lower cervical spinal nerves and the first thoracic spinal nerve.
  • The brachial plexus is a network of nerve fibers that run from the spine that are formed by the ventral rami of the lower four cervical and first thoracic nerve roots (C5–C8, T1).
  • The brachial plexus is responsible for cutaneous and muscular innervation of the entire upper limb, with two exceptions: the trapezius muscle is innervated by the spinal accessory nerve (CN XI) and an area of skin near the axilla is innervated by the intercostobrachial nerve.
  • Lesions on the brachial plexus can lead to severe functional impairment.
  • The right brachial plexus with its short branches, viewed from the front.

• Oculomotor (III) Nerve

  • The oculomotor nerve is the third paired cranial nerve.
  • Sympathetic postganglionic fibers also join the nerve from the plexus on the internal carotid artery in the wall of the cavernous sinus and are distributed through the nerve, for example, to the smooth muscle of levator palpebrae superioris.
  • It then runs along the lateral wall of the cavernous sinus, above the other orbital nerves, receiving in its course one or two filaments from the cavernous plexus of the sympathetic nervous system, and a communicating branch from the ophthalmic division of the trigeminal nerve.
  • Here the nerve is placed below the trochlear nerve and the frontal and lacrimal branches of the ophthalmic nerve, while the nasociliary nerve is placed between its two rami (the superior and inferior branch of oculomotor nerve).
  • Image of cranial nerves showing the position of the oculomotor nerve.

• 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 first three and the greater part of the fourth are connected by anastomotic loops and form the lumbar 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.
  • Its anterior root helps form the coccygeal plexus.