Deep Neck Spaces and Fascia

Overview

This lecture explains the deep neck spaces and the deep cervical fascia, focusing on how these fascial layers create distinct anatomical spaces in the neck and their importance in identifying normal and abnormal findings in imaging.

Cervical Fascia and Its Layers

• The neck is divided into suprahyoid (above hyoid bone) and infrahyoid (below hyoid bone) regions.
• The superficial cervical fascia is just under the skin and contains the platysma muscle.
• The deep cervical fascia is split into three planes: superficial (investing), middle (pre-tracheal), and deep (pre-vertebral).
• The superficial layer (investing) surrounds the sternocleidomastoid and trapezius muscles.
• The middle layer (pre-tracheal) surrounds the trachea, esophagus, thyroid, and strap muscles.
• The deep layer (pre-vertebral) encloses the vertebral column and paravertebral muscles.

Deep Neck Spaces

• The Carotid space lies between all three fascial layers and contains major vessels.
• The Visceral space (infrahyoid neck) contains the airway and digestive tract structures and is surrounded by the middle fascial layer.
• The Perivertebral space is encased by the deep layer, containing the vertebrae and related muscles.
• The Aylar fascia separates the visceral space from the perivertebral space, creating potential spaces.

Potential Spaces and Clinical Relevance

• The Retropharyngeal space (between middle fascia and Aylar fascia) can expand with infection/fluid, extending to T1.
• The Danger space (between Aylar fascia and deep fascia) can allow infection to spread down to the diaphragm.

Suprahyoid Neck and Additional Spaces

• Above the hyoid, the visceral space becomes the pharyngeal mucosal space.
• The masticator space contains the muscles of mastication and is surrounded by the superficial fascia.
• The parotid space encloses the parotid gland and lies lateral to the carotid space.
• The parapharyngeal space is a fat-filled space vital for identifying mass displacement on imaging.

Imaging and Mass Displacement

• The parapharyngeal space's displacement helps localize masses in neck scans.
• The direction of the fat displacement suggests the origin of the mass (masticator, parotid, carotid, or pharyngeal mucosal spaces).
• The stylomandibular tunnel helps distinguish between deep parotid and carotid space masses.

Key Terms & Definitions

• Suprahyoid/Infrahyoid neck — Above/below the hyoid bone.
• Superficial cervical fascia — Layer beneath the skin containing the platysma.
• Deep cervical fascia — Three-layered fascia dividing neck spaces.
• Investing layer — Same as superficial layer of deep cervical fascia.
• Pre-tracheal fascia — Same as middle layer of deep cervical fascia.
• Pre-vertebral fascia — Deepest layer, around vertebrae.
• Aylar fascia — Thin membrane separating visceral and perivertebral spaces.
• Parapharyngeal space — Fat-filled space critical for mass localization.

Action Items / Next Steps

• Review linked color-coded images and scroll through MRI/CT neck scans to identify fascial layers and spaces.
• Practice locating the parapharyngeal space and use its displacement to deduce the origin of neck masses.