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Anatomy of the pterygopalatine (sphenopalatine) fossa

Transcript

The pterygopalatine fossa, sometimes called the sphenopalatine fossa, is a cavity in our skull that sits behind the maxilla. We are going to think of the pterygopalatine fossa as a house for sale, and talk about its design, location, neighbours, and even the furnishings it comes with.

First, let’s talk about the shape of the house. The pterygopalatine fossa is shaped like an upside down trapezoidal prism and it is situated in a prime location, just posterior to the maxilla. So right off the bat, it makes sense that it’s bounded anteriorly by the posterior aspect of the maxilla!

Posteriorly, it’s bounded by the pterygoid process of the sphenoid. Medially, the fossa is bounded by the perpendicular plate of the palatine bone whereas laterally it opens into the pterygomaxillary fissure.

Its roof is formed by the infratemporal surface of the greater wing of the sphenoid bone and it is incomplete as there is an opening into the inferior orbital fissure. Finally, the floor is formed by the pyramidal process of the palatine bone with an opening into the palatine canal.

This means the pterygopalatine fossa’s neighbours include the middle cranial fossa, infratemporal fossa, orbit, nasal cavity, the roof of the oral cavity, and maxillary sinus and the pharyngeal vault .

Now, the pterygopalatine fossa communicates with its neighbors, aka surrounding structures, through many openings. First, it communicates with the middle cranial fossa through the foramen rotundum, located anteromedially on the sphenoid bone. The foramen rotundum provides passage for the maxillary nerve, which is the second main division of cranial nerve V.

Another connection to the middle cranial fossa is through the pterygoid canal within the sphenoid bone. The canal provides passage for the nerve and artery of the pterygoid canal.

The pterygopalatine fossa communicates with the infratemporal fossa through the pterygomaxillary fissure, which transmits the posterior superior alveolar nerve and artery and the maxillary artery. It communicates with the nasal cavity through the sphenopalatine foramen, which transmits the sphenopalatine artery and vein, and the nasopalatine nerve.

Fifth, it communicates with the orbit through the inferior orbital fissure, which provides passage for the zygomatic branch of the maxillary nerve and the infraorbital nerve, artery and vein.

Next, it communicates with the pharynx via the palatovaginal canal, which transmits the pharyngeal nerve and artery. Lastly, the pterygopalatine fossa communicates with the mucosa of the hard and soft palate via the palatine canal.

Before we move on, can you recall the boundaries of the pterygopalatine fossa?

Now, this house also comes fully furnished. Some of the most important structures you can find within the fossa include the terminal part of the maxillary artery and the proximal parts of its branches; their accompanying veins; the maxillary nerve; and the pterygopalatine ganglion.

First, the maxillary artery is one of the terminal branches of the external carotid artery. From its origin posterior to the lateral pterygoid muscle, it passes anteriorly through the infratemporal fossa, and eventually makes its way to the pterygomaxillary fissure.

Then, it enters the pterygopalatine fossa and eventually terminates as the sphenopalatine artery. The maxillary artery gives off branches along its trajectory which usually accompany the nerves entering and exiting the fossa.

First is the descending palatine artery, which passes through the palatine canal and divides into the greater palatine artery and lesser palatine artery to supply most of the soft palate and hard palate.

Next is the posterior superior alveolar artery which exits the fossa through the pterygomaxillary fissure and then enters the alveolar foramen of the maxilla to supply the maxillary sinus and the upper premolar and molar teeth and their gingivae.

There’s also the pharyngeal artery, which supplies the roof of the nasal cavity and the sphenoidal sinus, and the artery of the pterygoid canal, which supplies the tympanic cavity. Both branches also supply the pharynx and pharyngotympanic tube.

Next is the infraorbital artery which enters the inferior orbital fissure, travels through the infraorbital canal and exits the skull through the infraorbital foramen. It supplies the inferior oblique and inferior rectus muscles, lacrimal sac, maxillary canines and incisors, the mucosa of the maxillary sinus, and the overlying skin.

Finally, the sphenopalatine artery exits the pterygopalatine fossa through the sphenopalatine foramen. From here, it enters the nasal cavity, where it gives rise to lateral nasal and septal branches that supply its lateral and medial walls.