Posterior cervical space

The posterior cervical space is defined as the area in the posterolateral portion of the neck from the skull base to the clavicles deep to the sternomastoid and trapezius muscles but superficial to the prevertebral space. Seen from the side, the PCS has the appearance of a posteriorly tilted triangle. 

Boundaries:

• Deep margin: deep layer of deep cervical fascia, which separates the PCS from the anterior prevertebral space proper and the more posterior paraspinal prevertebral space
• Superficially: superficial layer of deep cervical fascia, which splits to enclose the sternomastoid and trapezius muscles
• Anteromedially: separated from the carotid space by the carotid sheath. 

Contents:

• Fat
• Spinal accessory nerve
• Lymph nodes 

Sources: Radiologic evaluation of the normal and diseased posterior cervical space. G D Parker and H R Harnsberger American Journal of Roentgenology 1991 157:1, 161-165