Nasopharyngeal Tonsil ( Adenoids )It is a subepithclial colletion of lymphoid tissue at the junction of roof and posterior wall of nasopharynx and causes the overlying mucous membrance to be thrown into radiating folds, it increases in size up to the age of six years and then gradually atrophies.

Nasopharyngeal Bursa ( Fig. 46.4 )It is an epithclial lined median recess found within the adenoid mass and extends from pharyngeal mucosa to the periosteum of the basiocciput. It represents the attachment of notochord to the pharyngeal entoderm during embry onic life. When infected, it may be the cause of persistent postnasal discharge or crusting. Sometimes an abscess can form in the bursa ( thornwaldts discase ).

Rathkes PouchIt is represented clinically by a dimple above the adenoids and is reminiscent of the buceal mucosal invagination, to form the anterior lobe of pituitary. A craniopharyngioma may arise from it.

Tubal TonsilIt is collection of subepithclial lymphoid tissue situated at the tubal elevation. It is continuous with adenoid tissue and forms a part of the waldeyers ring. When enlarged due to infection, it causes eustachian tube occlusion.

Sinus of MorgagniIt is s space between the base of the skull and upper free border of superior constrictor muscle. Through is enters ( i ) the eustachian tube, ( ii ) the levator veli palatini, ( iii ) tensor veli palatini and ( iv ) ascending palatine artery branch of the facial artery ( fig. 46.1 )

Passavants ridgeIt is a mucosal ridge raised by fibres of palatopharyngeus. It encircles the posterior and lateral walls of nasopharyn geal isthmus. Soft palate, during its contraction, makes firm contact with this ridge to cut off nasopharynx from the oropharynx during the deglutition or speech.

Epithelial lining of nasopharynxFunctionally, nasopharynx is the posterior extension of nasal cavity. It is lined by pseudostratifed cilited colum nar epithclium.

Lymphatic DrainageLymphatics of the nasopharynx, including those of the adenoids and pharyngeal end of custachian tube, drain into upper deep cervical nodes either directly or indirectly through retropharyngeal and parapharyngeal lymph nodes in the posterior triangel of the neck. Lymphatics of the nasopharynx may also cross midline to drain into contralateral lymph nodes.

Oropharynx

Applied anatomyOropharynx extends from the plane of hard palate above to the plane of hyoid bone below. It lies opposite the oral.

Diseases of pharynxCavity with which it communicates through oropharyngeal istlnusus . the latter is bounded above, by the soft palate ; below, by the upper surface of tongue, and o either side, by palatoglossal arch ( anterior pillar ).Boundaries of oropharynxPosterior wall it is related to retropharyngeal space and lies opposite the second and upper part of the third cervical vertebrae.

Anterior wall it is deficient above, where oropharynx communicates with the oral cavity, but below it presents :a) Base of tongue, posterior to circumvallate papillae.b) Lingual tonsil, one on either side, situated in the base of tongue. They may show compensatory enlargement following tonsillectomy or may be the sat of infection.c) Valleculae, they are cup-shaped depressions lying between the base of tongue and anterior surface of epiglottis. Each is bounded medially by the median glossoepiglottic fold and laterally by pharyngoepiglottic fold ( fig. 46.5 ). They are the seat of retention cysts.

Lateral wall it presents :a) Palatine ( fancial ) tonsil ( for details, see page 271 )b) Anterior pillar ( palatoglossal arch ) formed by the palatoglossus muscle.c) Poterior pillar ( palatopharyngeal arch ) formed by the palatopharyngeal muscle.

Both anterior and posterior pillars diverge from thye soft palate and enclose a triangular depression called tonsillar fossa in which is situated the palatine tonsil ( fig 46.6 )Boundary between oropharynx above and the hypopharynx below os formed by upper border of epiglottis and the pharyngoepiglottic fold.

Lymphatic drainageLymphatics from the oropharynx drain into upper jugular chain particularly the jugulodiglastric ( tonsillar ) node. The soft palate, lateral and posterior pharyngeal walls and the base of tongue also drain into retropharyngeal and parapharyngeal nodes and from there to the jugulodigastric and posterior cervical group. The base of tongue may drain bilaterally.

Hypopharynx ( laryngopharynx )

Applied anatomyHypopharynx is the lowest part of the pharynx and lies behind and partly on the sides of the larynx. Its superior limit is the plane passing from the body of hyoid bone to the posterior pharyngeal wall, while the inferior limit is loower border of cricoid cartilage where hypopharynx becomes continuous with oesophagus. Hypopharynx lies oppsite the 3td, 4td, 5td, 6th cervical vertebrae. Clinically, it is subdivided into three regions the pyroform sinus, post cricoid region and the posterior pharyngeal wall.1. Pyriform sinus ( fossa ). It lies on either side of the larynx and extends from pharyngoepiglottic fold to the upper end of oesophagus.It is bounded laterally by the thytohyoid membrane and the thyroid catilage and medially by the aryepiglottic fold, posterolateral sucface of arytenoid and cricoid cartilages. It forms the lateral channel for food. Foreign bodies may lodge in the pyriform fossa. Internal laryngeal nerve runs submucosally in the lateral wall of the sinus and thus is easly accessible for local anaesthesia, it is also through this nerve that pain is referred to the ear in carcinoma of the pyriform sinus.2. Post cricoid refion. It is the part of the anterior wall of laryngopharynx between the upper and lower borders of cricoid lamina. It is a common site for carcinoma in females suffering from plummer vinson syndrome ( fig 46.7 )3. Posterior pharyngeal wall. It extends from the level of hyoid bone to the level of cricoarytenoid joint.

Lymphatic drainagePyriform sinus is richly supplied by lymphatics which exit through the thyrohyoid membrane an drain into the upper jugular chain.Lymphatics of the posterior wall terminate in the lateral pharyngeal or parapharyngeal nodes and thence to the deep cervical lymph nodes.Lymphatics of post cricoid region also drain into the parapharyngeal nodes but may also darin nodes of supraclavicular and paratracheal chain.Rich lymphatic network of pyriform fossae explains the high frequency with which nodal metastases are seen in carcinoma of this region.Love u, bunda..