science

Nerve plexus

Nerve plexus is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Nerve plexus rather than just read about it. In short: A nerve plexus is a plexus (branching network) of intersecting nerves. A nerve plexus is composed of afferent and efferent fibers that arise from the merging of the anterior rami of spinal nerves and blood vessels.

Key takeaways

Nerve plexus belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Nerve plexus to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Nerve plexus from memory before moving on to harder problems.

Reference excerpt

A nerve plexus is a plexus (branching network) of intersecting nerves. A nerve plexus is composed of afferent and efferent fibers that arise from the merging of the anterior rami of spinal nerves and blood vessels. 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 nerves that arise from the plexuses have both sensory and motor functions. These functions include muscle contraction, the maintenance of body coordination and control, and the reaction to sensations such as heat, cold, pain, and pressure. There are several plexuses in the body, including:

Spinal plexuses Cervical plexus – serves the head, neck and shoulders Brachial plexus – serves the chest, shoulders, arms and hands Lumbosacral plexus Lumbar plexus – serves the back, abdomen, groin, thighs, knees, and calves Subsartorial plexus – below the sartorius muscle of thigh Sacral plexus – serves the pelvis, buttocks, genitals, thighs, calves, and feet Pudendal plexus Coccygeal plexus – serves a small region over the coccyx Autonomic plexuses Celiac plexus (solar plexus) – serves internal organs Auerbach's plexus (myenteric plexus) – serves the gastrointestinal tract Meissner's plexus (submucosal plexus) – serves the gastrointestinal tract Pharyngeal plexus of vagus nerve – serves the palate and pharynx Cardiac plexus – serves the heart

Spinal plexuses The following table shows the nerves that arise from each spinal plexus as well as the spinal level each plexus arises from.

Cervical plexus

The cervical plexus is formed by the ventral rami of the upper four cervical nerves and the upper part of fifth cervical ventral ramus. The network of rami is located deep to the sternocleidomastoid within the neck. The cervical plexus innervates muscles of the neck and areas of skin on the head, neck and chest. The deep branches innervate muscles, while the superficial branches supply areas of skin. A long branch (primarily of fibers of C4 and with contributions of fibers from C3 and C5; nervus phrenicus) innervates muscles of the diaphragm. The cervical plexus also communicates with the cranial nerves vagus nerve and hypoglossal nerve.

Brachial plexus

The brachial plexus is formed by the ventral rami of C5-C8-T1 spinal nerves, and lower and upper halves of C4 and T2 spinal nerves. The plexus extends toward the armpit. The ventral rami of C5 and C6 form upper trunk, the ventral ramus of C7 forms the middle trunk, and the ventral rami of C8 and T1 join to form the lower trunk of the brachial plexus. Under the clavicle, the trunks reorganize to form cords (fasciculi) around the axillary artery (arteria axillaris). The lateral cord (fasciculus lateralis) is formed by the upper and middle trunk, all three trunks join to form the posterior cord (fasciculus posterior), the lower trunk continues to the medial trunk (fasciculus medialis). The nerves (containing motor and sensory fibers) to the shoulder and to the upper limb emerge from the brachial plexus.

Lumbar plexus

Since the lumbar plexus and sacral plexus are interconnected, they are sometimes referred to as the lumbosacral plexus. The intercostal nerves that give rami to the chest and to the upper parts of the abdominal wall efferent motor innervation and to the pleura and peritoneum afferent sensory innervation are the only ones that do not originate from a plexus. The ventral rami of L1–L5 spinal nerves with a contribution of T12 form lumbar plexus. This plexus lies within the psoas major muscle. Nervi of the plexus serve the skin and the muscles of the lower abdominal wall, the thigh and external genitals. The largest nerve of the plexus is the femoral nerve. It supplies anterior muscles of the thigh and a part of skin distal to the inguinal ligament.

Sacral plexus

Ventral rami of L4–S3 with parts of L4 and S4 spinal nerves form the sacral plexus. It is located on the posterior wall of pelvic cavity (pelvis minor). Nervi of the plexus innervate the perineal region, buttocks and the lower limb. The largest nerve of the human body, the sciatic nerve, is the main branch that gives rami to the motor innervation of the muscles of the thigh, the leg, and the foot. Common peroneal nerve and its branches innervate some parts of the skin of the foot, the peroneal muscles of the leg, and the dorsal muscles of the foot.

Coccygeal plexus Coccygeal plexus originates from the ventral rami of spinal nerves S4, S5, and Co. It is interconnected with the lower part of sacral plexus. The only nerve of the plexus is the coccygeal nerve, that serves sensory innervation of the skin in the coccygeal region.

Autonomic plexuses Autonomic plexuses can contain both sympathetic and parasympathetic neurons. The cardiac plexus is located near the aortic arch and the carina of the trachea. The pulmonary plexus supplies innervation to the bronchial tree. The celiac, or solar plexus, is located around the celiac trunk and contains the celiac ganglia. The solar plexus is the largest autonomic plexus and provides innervation to multiple abdominal and pelvic organs. The superior mesenteric plexus includes the superior mesenteric ganglia and is located around the superior mesenteric artery. The inferior mesenteric plexus includes the inferior mesenteric ganglia and is located around the inferior mesenteric artery. Together, these plexuses innervate the intestines.

Some other plexuses include the superior and inferior hypogastric plexus, renal plexus, hepatic plexus, splenic plexus, gastric plexus, pancreatic plexus, and testicular plexus / ovarian plexus.

See also Plexus Brachial plexus Cranial nerve Spinal nerve List of anatomy mnemonics Nerve tract Neural pathway Neural circuit

Sources Henry Gray: Anatomy of the human body (Bartleby.com; Great Books Online) Richard S. Snell: Clinical neuroanatomy (Lippincott Williams & Wilkins, Ed.6th 2006) Philadelphia, Baltimore, New York, London. ISBN 978-963-226-293-2 Eldra P. Solomon - Richard R. Schmidt - Peter J. Adragna : Human anatomy & physiology ed. 2nd 1990 (Sunders College Publishing, Philadelphia) ISBN 0-03-011914-6 Jochen Staubesand (Ed.); R. Putz, R. Pabst, Johannes Sobotta: Sobotta Atlas of Human Anatomy I-II. (Urban & Schwarzenberg, München 1982) ISBN 3-541-72710-1 Saladin, Kenneth S. Anatomy & Physiology: The Unity of Form and Function. New York, NY: McGraw-Hill, 2007. Print.

References Instant Anatomy, 2010, webpage

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Illustrations

Worked examples

Example 1 — a first encounter with Nerve plexus

Start with the simplest possible case. Write down what Nerve plexus claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Nerve plexus before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Nerve plexus ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Nerve plexus

In research: Nerve plexus appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Nerve plexus in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Nerve plexus is common in secondary-school and first-year university syllabi. It links to neighbouring topics Nerve plexus, Peripheral nervous system, so understanding it makes those chapters shorter.
In everyday life: Look for Nerve plexus outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Nerve plexus in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Nerve plexus means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Nerve plexus out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nerve plexus in simple terms?

Why does Nerve plexus matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Nerve plexus?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Nerve plexus.