ANATOMY AND PHYSIOLOGY
of the tonsil. These are the openings of the tonsillar crypts which extend into
the substance of the tonsillar lymphoid tissue. The lateral surface of the
tonsil is covered by a fibrous capsule, separating it from the pharyngeal
aponeurosis, and providing a convenient plane of separation during the
removal of the tonsil. The lower pole of the tonsil is extended on to the dorsum
of the tongue, where it is called the lingual tonsil.
The arterial supply to the tonsil derives mainly from the tonsillar branch of
the facial artery and the descending palatine artery. The veins drain into the
pharyngeal plexus. Lymphatic drainage from the tonsil is into the upper deep
cervical glands, which may enlarge during tonsillar infection. There is an
intercommunicating ring of lymphoid tissue in the pharynx including the
pharyngeal tonsils, the palatine tonsils, and the cervical and retropharyngeal
glands, and this is called Waldeyer's ring.
PHYSIOLOGY OF THE TONSILS
There is considerable controversy regarding the importance of the role of the
tonsils in the body's defence against disease. It is probable that upper
respiratory organisms multiply in the tonsillar crypts and that the surrounding
lymphoid tissue manufactures antibodies against these organisms. This might
explain the 'physiological' enlargement of the tonsils that takes place in the
3-6 years age group when the child is exposed to frequent upper respiratory
infections, against which he gradually builds up some immunity.
Apart from this function of the tonsils, the pharynx affords a channel for
respiration and for swallowing.