Blood Supply and Innervation
The palatine tonsils are located inside the oropharynx between two mucosa-covered pillars on the lateral sides of the cavity, the anterior being the palatoglossal arch, and the posterior being the palatopharyngeal arch. Collectively they are referred to as the fauces. Between these arches is the tonsillar bed, within which lie the palatine tonsils and the nervous and arterial structures that supply them.
The palatine tonsils receive afferent nervous innervation via the tonsillar plexus, which has contributions from GSA fibers of the maxillary division of the trigeminal nerve via the lesser palatine nerves, and GVA fibers from the tonsillar branches of the glossopharyngeal nerve (CN ix). The glossopharyngeal nerve continues past the palatine tonsil and innervates the tongue to provide general and taste sensation. This nerve is most likely to be damaged during a tonsillectomy, which leads to reduced or lost general sensation and taste sensation to the posterior third of the tongue.
Blood supply is provided by tonsillar branches of five arteries: the dorsal lingual artery (of the lingual artery), ascending palatine artery (of the facial artery), tonsillar branch (of the facial artery), ascending pharyngeal artery (of the external carotid artery), and the lesser palatine artery (of the descending palatine artery). The tonsils venous drainage is by the peritonsillar plexus, which drain into the lingual and pharyngeal veins, which in turn drain into the internal jugular vein.
The palatine tonsil is one of the mucosa-associated lymphoid tissues (MALT), located at the entrance to the upper respiratory and gastrointestinal tracts to protect the body from the entry of exogenous material through mucosal sites. In consequence it is a site of, and potential focus for, infections, and is one of the chief immunocompetent tissues in the oropharynx. It forms part of the Waldeyer's ring, which comprises the nasopharyngeal tonsil or adenoid (NT), the paired tubal tonsils (TT), the paired palatine tonsils (PT) and the lingual tonsil (LT). From the pharyngeal side, they are covered with a stratified squamous epithelium, whereas a fibrous capsule links them to the wall of the pharynx. Through the capsule pass trabecules that contain small blood vessels, nerves and lymphatic vessels. These trabecules divide the tonsil into lobules.
In children, the tonsils are common sites of infections that may give rise to acute or chronic tonsillitis. However, it is still an open question whether tonsillar hypertrophy is also caused by a persistent infection. Tonsillectomy is one of the most common major operations performed on children. The indications for the operation have been complicated by the controversy over the benefits of removing a chronically infected tissue and the possible harm caused by eliminating an important immune inductive tissue.
The information that is necessary to make a rational decision to resolve this controversy can be obtained by understanding the immunological potential of the normal palatine tonsils and comparing these functions with the changes that occur in the chronically diseased counterparts.
Read more about this topic: Palatine Tonsil, Anatomy
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