The Alar Fascia and Danger Space: A Modern Review

Abstract

Purpose: Given the advancements in dissection modalities over the last decade, what is the current understanding of the alar fascia and its clinical implications as an access point into the danger space (DS)?The aim of the study is to provide an updated review of the alar fascia and danger space.Methods: A comprehensive search of the alar fascia and danger space was performed through PubMed databases up to August 2022. Thirty-two sagittal E12 sheet plastination slices of the head and neck were analyzed under a stereomicroscope to assess the morphology and continuity of the retropharyngeal, alar, and prevertebral fasciae (PVF and their respective potential spaces).Results: Recent advancements have provided evidence that the alar fascia is a true fascial layer between the retropharyngeal and danger spaces within the deep cervical region. Although its composition, histological features, and borders remain topics of controversy, the alar fascia is comprised of dense connective tissue and may serve as a physical barrier to prevent the spread of infection into the danger space. Complications arising from deep neck infections that invade the danger space include mediastinitis, necrotizing fasciitis, and empyema. Conclusion: A proper understanding of the anatomy, structure, function, and potential spaces is crucial to assessing the alar fascia and danger space routinely in clinical practice, especially when imaging.

Sudden Death: A Practical Autopsy Approach to Unexplained Mediastinitis Due to Fatal Untreated Neck Infections—A Systematic Review

“…Expertise in the anatomy of the neck and knowledge of cervical fasciae and spaces help to clarify the pathogenesis of DNM. Odontogenic, oropharyngeal, and cervical infections often lead to necrotizing fasciitis of the neck, spreading to soft tissues delimited by the deep cervical fascia [ 18 ]. The deep cervical fascia is anatomically divided into three layers: the superficial, middle, and deep layers.…”

“…The deep layer is made up of the alar fascia and prevertebral fascia. The deep cervical fascia layers delimit the virtual spaces of the neck: the retropharyngeal space and danger space [ 18 ]. The alar fascia therefore provides an anatomical and functional barrier that hinders the spreading of infections from retropharyngeal spaces into the thorax [ 18 , 19 ].…”

“…The deep cervical fascia layers delimit the virtual spaces of the neck: the retropharyngeal space and danger space [ 18 ]. The alar fascia therefore provides an anatomical and functional barrier that hinders the spreading of infections from retropharyngeal spaces into the thorax [ 18 , 19 ]. The upper limit of the alar fascia was identified by Scali et al, who placed it at the C1 vertebral level, while the inferior limit has been set at multiple vertebral levels, ranging from C6 to T2 [ 20 ].…”

Global Status and Future Trends of Fascia and Pain Research in 2013–2022: Bibliometric Analysis Based on CiteSpace and VOSviewer

“…(1) Support and shaping: the capsule, ligament, septum, and intermembrane formed by fascia play a mechanical role, such as fixing the position of organs and maintaining their morphology, 25 and it can limit the spread of diseases on different fascial planes. 26 (2) The generation and conduction of force: the fascial structure essentially gives its ability to transmit the produced power. The latter is a transporter of the created tension and stores mechanical energy in order to save myoelectric energy.…”

Fascial Nomenclature: Update 2024

“…The same deep layers of the neck can act as barriers to prevent the passage of infectious substances. The alar fascia or intercarotid fascia of the neck, in connection with retropharyngeal and prevertebral fasciae, if functional, acts as a barrier to prevent the spread of infections or abscesses towards the danger space (posterior to the paravertebral space) [ 11 ]. The density of the connective tissue that forms the alar fascia is compact and regular, innervated, and vascularized [ 11 ].…”