The supraodontoid space, also known as the supradental space or apical cave, is an extradural space at the anterior craniocervical junction superior to the odontoid process of C2 (dens axis).
Gross anatomy
Boundaries
The space is a cave-shaped region facing posteriorly with the following boundaries 1:
- inferior: alar ligaments and apex of the dens
- posterior: tectorial membrane and dura mater
- anterior: anterior atlanto-occipital membrane
- superior: foramen magnum and clivus
- lateral: occipital condyles
Contents
Contents encountered from anterior to posterior include the following 1:
- fat pads
- veins including a central knot of varicose veins of the vertebral venous plexus joined to surrounding cavernous sinuslike veins
- apical ligament
- small arterial arch known as the (supraodontoid) apical arterial arcade
- superior fasciculus of the cruciate (cruciform) ligament
- subtectorial membrane
Related pathology
In trauma patients, haemorrhage in the supraodontoid space presumably indicates apical ligament injury 2, and it is also a sign associated with tectorial membrane injury (termed the supradental space sign) 3.