Cervical Plexus and Associated Structures

Jul 25, 2024

Cervical Plexus and Associated Structures

Introduction

  • Cervical plexus supplies structures of the head, neck, and certain muscles.
  • Series covers cervical, brachial, lumbar, and sacral plexus.
  • Spinal cord view: anterior, highlighting the cerebellum, medulla, and pons.

Spinal Nerve Formation

  • Anterior and posterior rootlets from the spinal cord form spinal nerves.
  • Spinal nerves are paired and extend on both left and right sides of the body.
  • Spinal cord regions: cervical, thoracic, lumbar, sacral, and coccygeal segments.

Cervical Region

  • C1-C8: Eight pairs of spinal nerves.
  • Nerve exit points: Between occipital condyles, atlas (C1), and axis (C2).

Thoracic Region

  • T1-T12: Twelve pairs of spinal nerves.

Lumbar Region

  • L1-L5: Five pairs of spinal nerves.

Sacral Region

  • S1-S5: Five pairs of spinal nerves.

Coccygeal Segment

  • C1: One pair of spinal nerves.

Total spinal nerves: 31 pairs.

Cervical Plexus Specifics

  • Mainly formed by C1-C4 with some contribution from C5 (phrenic nerve).
  • Exits: Through intervertebral foramen between vertebrae.

Distribution of Nerves

  • C1: Exits between atlas and occipital condyles, gives two branches:
    • Hypoglossal nerve accompaniment (Cranial nerve XII).
    • Supplies two muscles: geniohyoid (elevates hyoid) and thyrohyoid (depresses hyoid, elevates larynx).
  • C2-C3 Branches:
    • Greater auricular nerve supplies skin over ear and parotid gland.
    • Transverse cervical nerve supplies skin on the anterior and lateral neck.
    • Lesser occipital nerve (C2): Supplies occiput, posterior, and lateral neck regions.

Ansā Cervicalis

  • Formed by superior (C1) and inferior (C2-C3) roots.
  • Supplies four muscles: superior belly of omohyoid, sternothyroid, sternohyoid, inferior belly of omohyoid.

Phrenic Nerve

  • Formed from C3, C4, and C5 roots.
  • Main function: Innervation of the diaphragm (essential for breathing).

Scalene and Longus Muscles

  • Branches: Supply anterior/middle scalene, levator scapulae, longus capitis, and longus colli muscles.

Accessory Nerve (Cranial Nerve XI)

  • Formation: Contributions from accessory nucleus and lateral funiculus (C1-C5 roots).
  • Muscles supplied: Sternocleidomastoid and trapezius.
  • Pathway: Travels through foramen magnum and jugular foramen.
  • Clinical relevance: Possible damage leading to muscle impairment.

Conclusion

  • Recap on the cervical plexus and its clinical significance.