The danger space (space 4) in the neck extends from the skull base to the posterior mediastinum and is bounded anteriorly by the alar fascia and posteriorly by the prevertebral fascia. Infection in this space can spread directly to the:

• A Anterior mediastinum
• B Posterior mediastinum to the level of the diaphragm ✓
• C Parapharyngeal space
• D Carotid sheath

Explanation

The danger space (retrovisceral compartment, space 4) lies between the alar fascia (anteriorly) and the prevertebral fascia (posteriorly). This space is continuous from the skull base to the diaphragm, allowing infections (e.g., from retropharyngeal abscess perforating the alar fascia) to track into the posterior mediastinum — causing descending necrotising mediastinitis. The pretracheal space (space 3) communicates with the anterior mediastinum. The parapharyngeal and carotid spaces are lateral compartments.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.