Chapter 1: Topographical and Clinical Anatomy

NECK

1. Cricothyroid membrane—It is also referred to as “conus elasticus.” This membrane is located about 2 cm inferior to the thyroid cartilage and superior to the ring-shaped cricoid cartilage (which itself lies at the level of the sixth cervical vertebra) (Figure 1-1). Cricothyroidotomy involves an incision through this membrane for emergent surgical airway management.

2. External and internal jugular veins (Figure 1-3)—The external jugular vein crosses the sternocleidomastoid muscle, pierces its clavicular head, and enters the subclavian vein. The sternocleidomastoid muscle also serves as a landmark for internal jugular vein cannulation (see Figures 1-2 and 1-15). The needle should enter at a 20-degree angle at the apex of the triangle between the two muscle heads (aiming laterally toward the patient’s nipple).

3. Thoracic duct—The thoracic duct is the largest vessel that drains lymphatic fluid from the body (Figure 1-4). It lies posterior to the left carotid artery and empties into the junction of the left subclavian and internal jugular veins (at the level of seventh cervical vertebra). Thoracic duct injury, which can occur during cannulation of these veins, typically presents with chylothorax.

4. Carotid and vertebral arteries (Figure 1-5)—The carotid artery is contained within the carotid sheath just posterior to the sternocleidomastoid muscle . The vertebral artery branches from the subclavian artery and ascends in the neck along the transverse foramina of C1-C6.

5. Stellate ganglion—The star-shaped stellate ganglion represents the fusion of the inferior cervical ganglion and the first thoracic ganglion. It receives preganglionic sympathetic fibers from upper thoracic portions of the spinal cord. The major topographical landmark for performing the anterior paratracheal block of the stellate ganglion is just inferior to Chassaignac tubercle (a transverse process of the sixth cervical vertebra, located at the level of the cricoid cartilage) (Figure 1-6).

6. Cervical spine landmarks

   • C3/4: Hyoid bone

   • C5: Thyroid cartilage

   • C6: Chassaignac tubercle, cricoid cartilage, end of larynx/start of trachea

   • C7: Vertebra prominens, level of stellate ganglion, thoracic duct

7. Hyoid bone—This U-shaped bone is located anterior to the third or fourth cervical vertebra (Figure 1-7). It supports the thyroid cartilage of the larynx by the thyrohyoid membrane. Blockade of the superior laryngeal nerve utilizes the greater horn of the hyoid bone for its landmark.

8. Superficial cervical plexus—Derived from C1 to C4 cervical spinal roots, this plexus of cutaneous nerves provides sensation to the anterolateral neck, mandible, occiput, and parts of the shoulder. It consists of four nerves: greater auricular, lesser occipital, transverse cervical, and supraclavicular (Figure 1-8). The major surface landmark for superficial cervical plexus blocks is the midpoint of a line drawn from the mastoid process to C6 (posterior border of the sternocleidomastoid muscle).

9. Deep cervical plexus (Figure 1-20).