Alar fascia
The alar fascia is a layer of fascia, sometimes described as part of the prevertebral fascia, and sometimes as in front of it.
Cranially, it reaches the skull, and caudally, it reaches the second thoracic vertebra.
It is the posterior border of the retropharyngeal space.
In 2015, the anatomy of the alar fascia was revisited using dissection in conjunction with E12 plastination. The authors revealed that the alar fascia originated as a well defined midline structure at the level of C1 and does not reach the base of the skull. It is suggested that the area between C1 and the base of the skull is a potential entry into the danger space.
