There is considerable question concerning the boundaries and relations of the lateral pharyngeal cleft. The purpose of this work is to determine the boundaries of this region, its relations with sur rounding spaces, and the existence of any direct communications between the lateral pharyngeal cleft and contiguous spaces. The results are based on the dissection of approximately 3 5 half heads. DESCRIPTION The lateral pharyngeal cleft is enclosed by a definite and discrete fascial boundary. Medially, it is bounded by the fascia on the lateral surface of the tensor veli palatini muscle, the fascia of the pharynx wall, and the fascia of the styloglossus muscle. Its lateral confine is the medial pterygoid and the interpterygoid fasciae.Anteriorly, above the level of the retromolar trigone, the cleft is closed by the attachment of the fused medial and interpterygoid fasciae to bucci nator fascia. Anteriorly, below the level of the retromolar trigone, where the styloglossus is contiguous with the pharynx wall, it is closed by the fascia sweeping lateralward to attach to the mandible at the junction of the body and ramus. A plane of fascia between the pharynx, the styloid process, and the posterior border of the man dibular ramus limits the cleft posteriorly. This potential space is limited above by the base of the skull, below by a fascial bridge be tween the pharynx and the mandibular ramus. With this general delineation we can consider the boundaries in greater detail.Covering the superficial surface of the superior constrictor is a fascial sheet, the peripharyngeal fascia (also identified as visceral or buccopharyngeal fascia (Figs. 1, 3, 4, 7 and 8). This sheet affixes