For trauma purposes the neck is divided into three distinct anatomical zones.

• Zone 1: from the sternal notch to the cricoid cartilage.

• Zone 2: from the cricoid cartilage to the angle of the mandible.

• Zone 3: from the angle of the mandible to the base of the skull.

Knowing the contents of each zone is important when considering possible injuries.

• Zone 1: the major vessels of the upper mediastinum, the lung apices, esophagus, trachea, thoracic duct, and thyroid gland.

• Zone 2: the carotid sheath and contents, vertebral arteries, esophagus, trachea, pharynx, and the recurrent laryngeal nerve.

• Zone 3: distal carotid and vertebral arteries, distal jugular veins.

At the level of the superior border of the thyroid cartilage the common carotid artery bifurcates into the internal and external carotid arteries.

At the level of the angle of the mandible, the internal and external carotid arteries are crossed superficially by the hypoglossal nerve and the posterior belly of the digastric muscle.

The external landmark of the pharyngoesophageal and laryngotracheal junctions is the cricoid cartilage. On esophagoscopy, this is located 15 cm from the upper incisor teeth.

The cricothyroid membrane is four fingerbreadths above the sternal notch.