Canine space

Infra-orbital is derived from infra- meaning below and orbit which refers to the eye socket.

[2] Signs and symptoms of a canine space abscess might include swelling that obliterates the nasolabial fold.

If left untreated, infections of this space will eventually spontaneously drain via the medial or lateral canthus of the eye, as this is the path of least resistance.

This can result in septic cavernous sinus thrombosis, which is a rare, but life-threatening condition.

[1] This occurs when pus (e.g. from a periapical abscess), perforates the buccal cortical plate of the maxilla above the level of attachment of the levator anguli oris muscle.

Diagram showing muscles of infra-orbital region. The levator labii superioris muscle is colored red.
Diagram showing muscles of the infra-orbital region. Levator anguli oris is colored red. The canine space is situated between the levator anguli oris muscle and the levator labii superioris muscle.