Location of the Sphenopalatine Foramen
The sphenopalatine foramen (foramen sphenopalatinum) is situated in the posterior section of the lateral wall of the bony nasal cavity. Topographically, it lies at the level of the superior nasal meatus (meatus nasi superior), which is positioned between the superior and middle nasal conchae. In the living state, this foramen is covered by the nasal mucosa. It serves as the primary gateway between the nasal cavity and the pterygopalatine fossa (fossa pterygopalatina).
Topography of the Lateral Nasal Wall
The lateral wall of the nasal cavity has a complex bony architecture, separating the nasal cavity from the orbit and the maxillary sinus. It is formed by the nasal bone, frontal process of the maxilla, lacrimal bone, orbital plate and ethmoid labyrinth of the ethmoid bone, and the nasal conchae (superior, middle, and inferior). Posteriorly, the wall is completed by the perpendicular plate of the palatine bone and the medial pterygoid plate of the sphenoid bone. The foramen sphenopalatinum is located in this posterior zone at the level of the superior nasal meatus, which is bounded by the superior and middle nasal conchae.
Vascular Contents
Vessels passing from the pterygopalatine fossa into the nasal cavity through this foramen include:
- Sphenopalatine artery (a. sphenopalatina): Entering the nasal cavity, it branches into two main groups. The posterior lateral nasal branches (rr. nasales posteriores laterales) supply the lateral nasal wall, nasal conchae, and paranasal sinuses. The posterior septal branch (r. septalis posterior) supplies the nasal septum.
- Accompanying veins: Venous drainage mirrors the arterial supply through the sphenopalatine foramen.
Neural Contents
The foramen transmits the posterior superior nasal branches (rami nasales posteriores superiores), which originate from the pterygopalatine ganglion and carry sensory and autonomic fibers:
- Posterior superior nasal branches enter the nasal cavity and divide into lateral and medial branches.
- Lateral branches (rami laterales) innervate the mucosa of the posterior superior and middle nasal conchae, nasal meatuses, posterior ethmoidal air cells, the roof of the choanae, and the pharyngeal opening of the auditory tube.
- Medial branches (rami mediales) supply the mucosa of the upper nasal septum.
- Nasopalatine nerve (n. nasopalatinus): The largest of the medial branches. After passing through the sphenopalatine foramen, it courses between the periosteum and mucosa of the nasal septum inferiorly and anteriorly toward the incisive canal, finally emerging onto the hard palate.
Role in the Pterygopalatine Fossa System
The sphenopalatine foramen provides critical communication between the pterygopalatine fossa (fossa pterygopalatina) and the nasal cavity. The pterygopalatine fossa is a small, inverted pyramidal space containing the pterygopalatine ganglion (ganglion pterygopalatinum). Through the sphenopalatine foramen, the major neurovascular structures (sphenopalatine vessels and posterior superior nasal nerves) access the nasal mucosa.