This wall is of most significance to the otorhinolaryngologist because of its proximity to the para nasal sinuses. . It is composed of :
- The frontal process of maxilla
- The lacrimal bone
- Lamina papyracea of the ethmoid
- Lesser wing of sphenoid bone.
Anteromedially: fossa for lacrimal sac which in demarcated by anterior and posterior lacrimal crest.
Foramina for the anterior and posterior ethmoid vessels and nerves are located at the frontoethmoidal suture where the medial wall join the roof. Their position is variable a rule of 24-12-6 has been suggested (in mm) from the anterior lacrimal to the anterior ethmoidal foramen, likewise from the anterior ethmoidal foramen to the posterior ethmoid foramen and posterior ethmoidal foramen to the optical canal.
The level of cribiform plate is also indicated by anterior ethmoidal foramen but this is not much reliable
- 16% has no Anterior Ethmoidal Foramen
- 30% has Multiple foramen
- 4.6% none
Clinical importance
- Lamina papyracea is the medial limit for endoscopic nasal surgery.
- Medial wall is extremely thin and some time naturally dehiscent, thus it is a poor anatomical barrier to the pathological pathway. The thinnest portion of the medial wall is the lamina papyracea which separates the ethmoidal sinuses from the orbit. Infections from ethmoidal sinus can easily breach this paper thin bone and affect the orbital contents.
