Anatomy Monday: Lateral Fossa / Incisive Fossa / Canine Fossa


Today’s anatomy is by request for the lateral fossa also known as the incisive fossa and canine fossa.  The lateral fossa is  depression of the maxilla around the root of the maxillary lateral incisors.  It presents as a diffuse radiolucent area around the root of the lateral incisor.

incisive fossa

Lateral incisor periapical radiographs – left shows the lateral fossa with a yellow dotted line and right shows the lateral fossa without the animation.

It is important to note that this area is normal anatomy and not pathosis.  If there is a question of bone loss due to inflammation evaluate the lamina dura and periodontal ligament space carefully to determine if it is intact around the entire root.

If it is intact, the radiolucent is normal anatomy – lateral fossa.

If it is not intact and is continuous with the radiolucent area, pathosis of odontogenic origin should be considered.

Lateral incisor periapical radiograph - radiolucent area at apex of lateral incisor continuous with periodontal ligament space indicating pathosis of odontogenic origin.

Lateral incisor periapical radiograph – radiolucent area at apex of lateral incisor continuous with periodontal ligament space indicating pathosis of odontogenic origin.

Many times the superimposition of the ala of the nose will make the lateral fossa appear more radiolucent causing over-interpretation of pathosis in this region.

Lateral incisor periapical radiographs - left with ala outlined in yellow and right without animation.

Lateral incisor periapical radiographs – left showing the ala of the nose outlined in yellow and right without animation.

If you have any questions or comments about the lateral fossa, please leave them below. Thanks and enjoy!

Leave a Reply