The four major nerve plexuses in the body are the cervical plexus, brachial plexus, lumbar plexus, and sacral plexus. These plexuses are networks of intersecting nerves that serve specific regions of the body.
Nerve Plexuses Overview
Nerve plexuses are crucial components of the peripheral nervous system, formed by the ventral rami of spinal nerves (except for the thoracic region). These plexuses redistribute nerve fibers, ensuring that each branch contains fibers from multiple spinal nerves. This arrangement provides a degree of redundancy, so damage to a single spinal nerve may not result in complete paralysis of any particular muscle.
The Four Major Nerve Plexuses
Here's a breakdown of the four major nerve plexuses, including their location as noted in the reference:
| Plexus | Location | Spinal Nerve Roots Primarily Involved | Region Served |
|---|---|---|---|
| Cervical Plexus | Cervical Level | C1-C4 | Neck, diaphragm, and some head regions |
| Brachial Plexus | Cervical Level | C5-T1 | Shoulder, arm, forearm, and hand |
| Lumbar Plexus | Lumbar Level | L1-L4 | Anterior and medial thigh |
| Sacral Plexus | Sacral Level | L4-S4 | Lower back, pelvic region, buttocks, posterior thigh, leg, and foot |
Detailed Descriptions of Each Plexus
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Cervical Plexus: Located in the neck, deep to the sternocleidomastoid muscle. It provides sensory and motor innervation to the neck, parts of the head, and the diaphragm.
- Key Nerves: Phrenic nerve (innervates the diaphragm).
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Brachial Plexus: Located in the shoulder and formed by the ventral rami of C5-T1. Supplies the upper limb.
- Key Nerves: Axillary, musculocutaneous, median, ulnar, and radial nerves.
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Lumbar Plexus: Located in the lumbar region within the psoas major muscle. Supplies the anterior and medial thigh.
- Key Nerves: Femoral and obturator nerves.
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Sacral Plexus: Located in the pelvis and formed by the ventral rami of L4-S4. Supplies the lower limb and pelvis.
- Key Nerves: Sciatic nerve (the largest nerve in the body, which then splits into the tibial and common fibular nerves).
The reference states: "Of the four nerve plexuses, two are found at the cervical level, one at the lumbar level, and one at the sacral level, forming the cervical plexus, brachial plexus, lumbar plexus, and saccral plexus, respectively (Figure 2)." Note: While the brachial plexus originates at the cervical level, it extends into the axilla (armpit) and upper limb.
