Alar fascia

The alar fascia a portion or prevertebral fascia that may or may not be considered a distinct anatomical structure. When acknowledged, it is described as anterior to the prevertebral fascia.

Anatomy
Superiorly, it extends to the base of the skull; inferiorly, it extends to the second thoracic vertebra. Inferiorly, it unites with the visceral fascia of the neck.

Anatomical relations
The alar fascia represents the posterior boundary of the retropharyngeal space.

Research
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.