Carotid sheath

CAROTID SHEATH

Definition Formation Contents Relations Clinical Anatomy

1 Carotid Sheath

  • Carotid sheath is a derivative of the deep cervical fascia.
  • It is a condensation of the fibroareolar tissue around the main vessels of the neck.

2 Formation

  • Anterior aspect → formed by pretracheal fascia.
  • Posterior aspect → formed by prevertebral fascia.

Extent

  • Extends superiorly to the base of skull.
  • Extends inferiorly to the root of neck.

3 Contents of Carotid Sheath

  1. Common and internal carotid arteries
  2. Internal jugular vein
  3. Vagus nerve (X)
  4. Cranial nerves IX, X, XI, XII in the upper part
    • They pierce the carotid sheath at different points.

4 Relations of Carotid Sheath

1. Ansa Cervicalis

  • Lies embedded in the anterior wall of the carotid sheath.

2. Cervical Sympathetic Chain

  • Lies behind the sheath.
  • It is plastered to the prevertebral fascia.

3. Sternocleidomastoid

  • The sheath is overlapped by the anterior border of sternocleidomastoid.
  • The sheath is fused to the layers of the deep cervical fascia.

5 Clinical Anatomy

  • Carotid sheath is:
    • Thick around the arteries.
    • Thin around the vein.
  • This permits expansion of the internal jugular vein during increased venous return.
  • The wall of the carotid sheath is excised to remove lymph nodes adherent to the internal jugular vein during block dissection of the neck.

This is usually done in:

  • Cancers
  • Tuberculosis

6 Carotid Sheath — Key Information

Carotid sheath → Derivative of deep cervical fascia

Formation

Anteriorly → Pretracheal fascia
Posteriorly → Prevertebral fascia

Extent

Superiorly → Base of skull
Inferiorly → Root of neck

Contents

  1. Common carotid artery
  2. Internal carotid artery
  3. Internal jugular vein
  4. Vagus nerve

Relations

Ansa cervicalis → anterior
Sternocleidomastoid (SCM)
Cervical sympathetic chain → posterior
Prevertebral fascia

Clinical Integration

Carotid sheath is thin around the vein → permits venous return.