Anatomy of palatine tonsil

  • The palatine tonsil is an ovoid mass of lymphoid tissue located in the oropharynx between the anterior and posterior pillars
  • It has a 2 surfaces – medial and lateral and 2 poles – upper and lower

Medial surface

  • It is lined by stratified squamous non keratinising epithelium which dips into the crypts
  • The crypts are 12-15 in number
  • Secondary crypts arise from the primary crypts and extend into the substance of the tonsil
  • On of the crypts located in the upper part are larger than the rest – crypta magna
  • It represents the ventral part of second pharyngeal pouch
  • The crypts serve to increase the surface area of the tonsil
  • The crypts may be filled witth cheesy material – epithelial debris, food particles and bacteria

Lateral surface

  • It is covered by the fibrous capsule of the tonsil
  • The tonsillar bed is separated from the capsule by loose areolar tissue
    • This makes it is easy to dissect the tonsil from its bed during tonsillectomy
    • It is the site of collection of pus in peritonsillar abscess (quinsy)
  • Some fibers of palatoglossus and palatopharyngeus gets attached to capsule of tonsil

Upper pole

  • It extends into the soft palate
  • There is a semilunar fold of mucous membrane which covers the medial part of the upper pole
    • It extends from anterior pillar to posterior pillar
    • It encloses a potential space – supratonsillar fossa

Lower pole

  • It is attached to the tongue
  • A triangular fold of mucous membrane extends from the anterior tonsillar pillar to the lower pole
    • It encloses a space – anterior tonsillar space
  • The lower pole is separated from the tongue by the tonsillolingual sulcus
    • This sulcus may harbour carcinoma

Bed of tonsil

Blood supply

Venous drainage

  • Blood from the tonsil drains into the paratonsillar vein which in turn drains into the common facial vein and pharyngeal venous plexus

Lymphatic drainage

  • Lymphatics from the tonsil pierce the superior constrictor and drain into the upper cervical lymph nodes especially jugulodigastric (tonsillar) lymph node
    • Enlarged non tender jugulodigastric lymph node is a sign of chronic tonsillitis

Nerve supply

  • Lesser palatine branch of sphenopalatine ganglion
  • Glossopharyngeal nerve

Functions of tonsil

  • It has a protective function in that it prevents entry of pathogens through the nasal and oral route
  • The crypts on the surface of the tonsil serve to increase the surface area and increase the efficiency of protection against pathogens
  • It forms a part of Waldeyer’s lymphatic ring

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