The pterygopalatine fossa, which is also known as the sphenopalatine fossa, is a bony space within the skull that is created by opposing anatomical structures of different shapes and sizes.
It has a funnel-like appearance, with the base narrowing towards the cranium and the opening widening towards the oral cavity. The fossa contains many openings that serve as the passageways for various neurovascular structures, where some of them course towards the cranial content and the others leave it.
Anterior wall: infratemporal surface of the maxilla
Posterior wall: pterygoid process of the sphenoid bone
Medial wall: palatine bone
Roof: posterior wall of the bony orbit, inferior surface of the sphenoid bone, orbital plate of the palatine bone
Floor: pyramidal process of the palatine bone
Infraorbital fissure - infraorbital and zygomatic nerves
Palatine canal - greater and lesser palatine nerves
Sphenopalatine foramen - sphenopalatine artery, posterior and superior nasal nerves
Pharyngeal canal - pharyngeal nerves and vessels
Pterygoid canal - nerve of the pterygoid canal (Vidian nerve)
Foramen rotundum - maxillary nerve
Pterygomaxillary fissure - maxillary artery
In this article, the fosse's borders, openings, contents, arterial and vascular supply as well as innervation will be discussed.
The infratemporal surface of the maxilla serves as the anterior wall for the fossa, while the posterior wall is formed by the pterygoid process of the sphenoid bone. Cranially the posterior wall of the bony orbit resides together with the inferior surface of the sphenoid bone, as well as the orbital plate of the palatine bone which both contribute to the orbit. In addition, they also contribute to the ceiling of the cavity.
Caudally, the pyramidal process of the palatine bone limits the extension of the fossa. There is no lateral wall but a direct communication between the pterygopalatine fossa and the pterygomaxillary fissure. Medially, the third wall that is made up of part of the palatine bone; here sits the pyramidal process of the structure.
The pterygopalatine fossa has a great many openings that allow for various anatomical structures to enter, pass through and exit the cavity. The openings shall be listed according to the border in which they exist, save the anterior border, for it has none. Superiorly, the inferior orbital fissure can be seen, which connects the fossa to the posterior part of the bony orbit.
Inferiorly, the palatine canal communicates directly with the oral cavity. Laterally an unnamed opening joins the two fossae as mentioned above. Medially the sphenopalatine foramen allows the fossa to communicate with the nasal cavity.
Lastly, the posterior border has the most openings, including the pharyngeal canal which links up to the nasopharynx, the pterygoid canal and the foramen rotundum which is the fosse’s only link to the internal part of the cranium, specifically the middle cranial fossa.
Contents, Blood Supply and Innervation
There are two directions in which the contents of the pterygopalatine fossa may go. There are those structures that enter the fossa and those that leave it. In this way the main contents will be categorized and discussed. The structures that enter the fossa include the maxillary nerve via the foramen rotundum and the maxillary artery via the pterygomaxillary fissure.
These two structures break up into their terminal branches once inside the fossa and form radiating neurovascular bundles. In turn the maxillary branches receive fibers from other nervous origins such as the facial nerve, which enter the fossa via the pterygoid canal.
The structures that leave the fossa include visceral nerve fibers that leave the pterygopalatine ganglion and enter the specific maxillary branches, the infraorbital and zygomatic nerves which leave the fossa via the inferior orbital fissure and the greater and lesser palatine nerves which descend through the palatine canal.
Also, the posterior and superior nasal nerves and the sphenopalatine artery pass through the sphenopalatine foramen in order to enter the nasal cavity. The posterior and superior alveolar nerves pass on into the pterygomandibular fissure which continues to the infratemporal fossa.
Finally, the pharyngeal canal acts as an exit for the pharyngeal nerves and vessels. Venous drainage, which of course exits the fossa includes branches like:
- the posterior superior alveolar veins
- the pharyngeal vein
- the descending palatine vein
- the infraorbital vein
- the sphenopalatine vein
- the vein of the pterygoid canal
- the inferior ophthalmic vein
- the pterygoid plexus
It should be noted that the contents above, help supply each and every area of the fossa as they enter and exit the space.
The borders of the pterygopalatine fossa are the following:
- Anterior wall - maxilla
- Posterior wall - Pterygoid process of sphenoid bone
- Cranially - Posterior wall of orbit, inferior surface of sphenoid, orbital plate of palatine bone
- Caudally - Pyramidal process of palatine bone
- Medially - Palatine bone
The communications and foramina of the pterygopalatine fossa are the following:
- Inferior orbital fissure
- Palatine canal
- Sphenopalatine foramen
- Pharyngeal canal
- Pterygoid canal
- Foramen rotundum
The contents of the pterygopalatine fossa are the following:
- Maxillary nerve
- Maxillary artery
- Facial nerve
- Pterygopalatine ganglion
- Infraorbital nerve and vein
- Zygomatic nerve
- Greater palatine nerve
- Lesser palatine nerve
- Posterior nasal nerve
- Superior nasal nerve
- Sphenopalatine artery and vein
- Pharyngeal nerve
- Pharyangeal artery and vein
- Descending palatine vein
- Vein of the pterygoid canal
- Inferior ophthalmic vein
- Pterygoid plexus