Ch. 7 The Nervous System

Marieb - Essentials of Human Anatomy & Physiology 13th Edition

Marieb13th EditionEssentials of Human Anatomy & PhysiologyISBN: 9780135624340Not the one you use?Change textbook

Marieb 13th Edition

Ch. 7 The Nervous System

Problem 20

Chapter 7, Problem 20

Name the four major nerve plexuses formed by the ventral rami and the body region served by each.

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Identify what a nerve plexus is: A nerve plexus is a network of intersecting nerves formed by the ventral rami of spinal nerves. These plexuses allow for the redistribution of nerve fibers to serve specific body regions.

Understand the four major nerve plexuses: The four major nerve plexuses are the cervical, brachial, lumbar, and sacral plexuses. Each serves distinct regions of the body.

Describe the cervical plexus: The cervical plexus is formed by the ventral rami of spinal nerves C1-C4. It serves the neck region and parts of the head, including the phrenic nerve, which controls the diaphragm.

Describe the brachial plexus: The brachial plexus is formed by the ventral rami of spinal nerves C5-T1. It serves the shoulders, arms, and hands, providing motor and sensory innervation to these regions.

Describe the lumbar and sacral plexuses: The lumbar plexus is formed by the ventral rami of spinal nerves L1-L4 and serves the lower abdomen, thighs, and parts of the legs. The sacral plexus is formed by the ventral rami of spinal nerves L4-S4 and serves the pelvis, buttocks, and lower limbs, including the sciatic nerve.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Nerve Plexuses

Nerve plexuses are networks of intersecting nerves that arise from the ventral rami of spinal nerves. They allow for the redistribution of nerve fibers to form peripheral nerves that innervate specific body regions. The major plexuses include the cervical, brachial, lumbar, and sacral plexuses, each serving distinct areas of the body.

Cervical Plexus

The cervical plexus is formed by the ventral rami of the first four cervical nerves (C1-C4). It primarily innervates the neck, parts of the shoulder, and diaphragm through the phrenic nerve. This plexus is crucial for motor and sensory functions in the upper body and plays a significant role in breathing.

Brachial Plexus

The brachial plexus is formed by the ventral rami of spinal nerves C5 to T1. It innervates the upper limb, including the shoulder, arm, and hand, through major nerves such as the median, ulnar, and radial nerves. This plexus is essential for both motor control and sensory perception in the upper extremities.

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