Dorlands/Elsevier 12745223 | ||
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Similar Pterygomandibular raphe, Parapharyngeal space, Retropharyngeal space | ||
The danger space or alar space, is a region of the neck. The common name originates from the risk that an infection in this space can spread directly to the thorax, and, due to being a space continuous on the left and right, can furthermore allow infection to spread easily to either side.
Contents
Anatomy
It is bounded superiorly by the skull base, anteriorly by the alar fascia and posteriorly by the prevertebral fascia. It comes to an end at the level of the diaphragm.
The retropharyngeal space is found anterior to the danger zone, between the alar fascia and buccopharyngeal fascia. There exists a midline raphe in this space so some infections of this space appear unilateral.
Imaging
On CT or MRI it is only visible when distended by fluid or pus, below the level of T1-T6, as the retropharyngeal space ends at this level, allowing distinction between the two entities.
History
It was first characterized in 1938.
