The neck has four major compartments (Fig. 8.5), which are enclosed by an outer musculofascial collar:
The vertebral compartment contains the cervical vertebrae and associated postural muscles.
The visceral compartment contains important glands (thyroid, parathyroid, and thymus), and parts of the respiratory and digestive tracts that pass between the head and thorax.
The two vascular compartments, one on each side, contain the major blood vessels and the vagus nerve.