Tonsils (Palatine Tonsil Or Faucial Tonsil)
- Palatine tonsils are masses of lymphoid tissue that can be seen on the left and right sides at the back of the throat. There are two palatine tonsils, and each palatine tonsil (right or left) lies in the tonsilar sinus (tonsilar fossa) on the lateral wall of oropharynx. Tonsilar fossa bounded by the palatoglossal fold in front and the palatopharyngeal fold behind. Tonsils are lined by non -keratinized stratified squamous epithelium. Medial surface of each tonsil has 15-20 crypts, the largest of which is called Intratonsillar cleft or crypta magna (which represents persistence of the ventral portion of the second pharyngeal pouch).
- The plica triangularis is a fold of mucous membrane covering the anteroinferior part of tons; Plica semilunaris is semilunar fold that may cross the upper part of tonsilar sinus.
- Tonsilar bed is formed from within - outwards by :-
- Pharyngobasilar fascia
- Superior constrictor and palatopharyngeus muscle
- Styloglossus (below)
- Buccopharyngeal fascia
Blood supply of tonsils
The tonsil is supplied by five arteries:-
- Tonsilar branch of facial artery. This is the main artery.
- Ascending pharyngeal artery from external carotid.
- Ascending palatine, a branch of facial artery.
- Dorsal linguae branches of lingual artery.
- Descending palatine branch of maxillary artery.
Nerve supply of tonsils
Lesser palatine branches of sphenopalatine ganglion and glossopharyngeal nerve (major supply)provide sensory nerve supply to the tonsils. Glossopharyngeal nerve also gives sensory supply to middle ear (through tympanic plexus). Therefore, pain from the tonsils can be referred to middle ear along glossopharyngeal nerve.
Lymphatics pass to jugulodigastric nodes (upper deep cervical nodes.
The tonsil develops from ventral part of second pharyngeal pouch.