Roof of the parapharyngeal space: defining its boundaries and clinical implications.

The roof of the parapharyngeal space (PPS) is poorly defined. Although it is generally described as having prestyloid and poststyloid compartments, we believe that these terms are imprecise. Therefore, we define its boundaries, partition, and compartments. We completed macroanatomical and microanatomical dissections in 10 specimens from 5 human cadaver heads; bone measurements in 50 dry skulls; and axial and coronal cross-sectional studies in 2 cadaveric specimens. The PPS roof is bordered laterally by the medial pterygoid fascia and medially by the pharyngobasilar fascia. The tensor veli palatini fascia (TVPF) partitions this roof into an anterolateral compartment containing fat and part of the deep lobe of the parotid gland, and a posteromedial compartment containing the cartilaginous part of the eustachian tube, internal carotid artery, internal jugular vein, and cranial nerves IX through XII. The anteroposterior length measures 32 mm (range, 26.1 to 36.9 mm), and the mediolateral width measures 16.3 mm (range, 12.1 to 21.3 mm). The PPS roof has 3 important bony landmarks (ie, scaphoid fossa, styloid process, sphenoid spine); 3 important fasciae (ie, medial pterygoid fascia, TVPF, pharyngobasilar fascia); and 2 compartments, which are anterolateral and posteromedial to the TVPF. We believe that this is the first report to specifically focus on the roof of the PPS.