Inside the skull, the base is subdivided into three large spaces, called the anterior cranial fossa, middle cranial fossa, and posterior cranial fossa (fossa = “trench or ditch”) (Figure 4). From anterior to posterior, the fossae increase in depth.

THE pterygopalatine fossa is an area, centrally located in the head, which serves as a distribution centre for the vessels and nerves of the middle third of the face. In this small area, which can be approached with relative ease, many important structures are crammed together; hence its surgical importance.

To perform an endoscopic approach to the pterygopalatine fossa, a large maxillary antrostomy is first completed that extends posteriorly to the level of the posterior wall of the maxillary sinus. A mucosal flap is developed from the posterolateral nasal wall to the crista ethmoidalis.

Bounded laterally by the brachioradialis and medially by the pronator teres, the fossa contains the tendon of the biceps brachii, the brachial artery and the median nerve. The floor is formed by the brachialis.