**3.2 Pharyngeal tonsil**

Pharyngeal tonsil is the superior-most of the Waldeyer's ring and located above the soft palate in the posterosuperior roof of the nasopharynx as a single median unencapsulated mass with 12–15 shallow, crypt-like invaginations. The pharyngeal bursa, a blind mucosal sac, may be seen in the posterior median wall of the nasopharynx above the SPCm. A median longitudinal groove extends from this sac inferiorly [6]. Anterosuperiorly, the pharyngeal tonsil is usually lined by pseudostratified ciliated columnar epithelium (respiratory epithelium), whereas posteroinferiorly the areas adjacent to the oropharynx is covered by stratified epithelium. These mucosal folds containing numerous lymphoid

nodules commonly enlarge and become adenoid which results in respiratory difficulties and nasal obstruction during childhood and often start to involute after 7 years of age or even atrophied in the adult. Chronic inflammation of the pharyngeal tonsil results in hyperplasia and hypertrophy of the lymphoid tissue known as adenoid [7].

The arterial supply of it comes from ascending pharyngeal artery, pharyngeal branch of the maxillary artery, artery of the pterygoid canal, basisphenoid artery, ascending palatine, and tonsillar branch of the facial artery. It has a lymphatic drainage into upper deep cervical within the parapharyngeal space (PPS) and retropharyngeal lymph nodes [7].
