The deep spaces of the head and neck refer to compartments delimited by the deep cervical fascia. While these concepts overlap with traditional anatomical descriptions, their existence highlights the importance of fascia in confining various pathologies.

A knowledge of these spaces not only allows for better communication between radiologists and specialists familiar with imaging of this region but also aids in diagnosis as each space has a distinct group of pathologies. 

Gross anatomy

Three layers of deep cervical fascia form the boundaries of the deep spaces in the neck ^5,6:

1. superficial layer: investing fascia of the sternocleidomastoid and trapezius muscles, fascia of the muscles of mastication, fascia between the hyoid and mandible that forms the floor of the submandibular space, at least some of the fascia covering the parotid gland
2. middle layer: strap muscle fascia, visceral fascia that encloses the thyroid gland and aerodigestive tract (pharynx, larynx, trachea, esophagus)
3. deep layer: perivertebral fascia of the prevertebral and paraspinal muscles, alar fascia

All three layers contribute to the carotid sheath.

Contents

The compartmental definitions vary somewhat by source ^1,5-7. The neck spaces are often divided into the suprahyoid (between the base of the skull and hyoid bone) and infrahyoid (between the hyoid bone and clavicles) spaces, as the anatomy of the deep cervical fascia is slightly different above and below the hyoid bone. Some spaces cross the hyoid bone and course the entire neck.

• suprahyoid neck
  • parotid space
  • masticator space, including or contiguous with the buccal space
    • infrazygomatic masticator space (sometimes simply called the masticator space) ⁸
      • pterygomandibular space
      • submasseteric space
    • suprazygomatic masticator space (or temporal fossa ⁸)
      • superficial temporal space
      • deep temporal space
  • submandibular space, including or contiguous with the sublingual space and submental space
  • (prestyloid) parapharyngeal space
• suprahyoid and infrahyoid neck
  • carotid space (or poststyloid parapharyngeal space in the suprahyoid neck, carotid sheath in the infrahyoid neck ⁷)
  • visceral space (infrahyoid in some definitions ⁷), including or contiguous with pharyngeal mucosal space (suprahyoid)
  • retropharyngeal space, including or contiguous with danger space
  • perivertebral space, including prevertebral space
  • posterior cervical space
  • sternocleidomastoid‐trapezius compartment ⁵
• infrahyoid neck
  • anterior cervical space
  • suprasternal space
  • strap muscle compartment ⁵

Relations

Many of the deep neck spaces can be described in relation to the (prestyloid) parapharyngeal space, which lies in a central location on each side of the deep face and suprahyoid neck. Directional deviation of the parapharyngeal fat helps localize pathology in these adjacent compartments.

• submandibular space is anterior to the parapharyngeal space
• masticator space is anterolateral to the parapharyngeal space
• parotid space is lateral to the parapharyngeal space
• carotid (poststyloid parapharyngeal) space is posterior to the parapharyngeal space
• retropharyngeal space is posteromedial to parapharyngeal space
• perivertebral space is posterior to the retropharyngeal space

Related pathology

Many of the disease states that affect the deep structures of the head and neck are confined to one compartment. However, there are some diseases that are trans-spatial. A list of differentials for related pathology can be found in the article for each individual space.