Anatomy lec 5

• Tonsils


  Collections of lymphatic tissue within the pharynx that collectively form Waldeyer's ring

  
• Tonsils


  • They contain T cells, B cells and macrophages
  • They have an important role in fighting infection as the first line of defence against pathogens entering through the nasopharynx or oropharynx
• Palatine tonsils


  Located between the palatoglossal arch anteriorly and the palatopharyngeal arch posteriorly, covered by a fibrous capsule laterally and stratified squamous epithelium medially, penetrated by 15-20 crypts

  
• Palatine tonsils


  • Arterial supply from the tonsillar branches of 5 arteries: ascending palatine, tonsillar, ascending pharyngeal, dorsal lingual, and lesser palatine
  • Venous drainage to the internal jugular vein via the peritonsillar plexus of lingual and pharyngeal veins

  
• Lingual tonsils


  Small round elevations on the most posterior part of the tongue base, responsible for the irregular appearance of the posterior tongue surface

  
• Lingual tonsils


  • Blood supply from the lingual, tonsillar, and ascending pharyngeal arteries
  • Innervated by the glossopharyngeal nerve

  
• Pharyngeal tonsils (adenoids)


  The most superior tonsils that lie in the midline in the roof of the nasopharynx, with a thinner covering capsule and no crypts

  
• Pharyngeal tonsils (adenoids)


  • Arterial supply from the ascending palatine, ascending pharyngeal, pharyngeal branch of the maxillary, artery of the pterygoid canal, basisphenoid, and tonsillar branch of the facial artery
  • Venous drainage via numerous small veins that pierce the superior constrictor muscle to empty into the pharyngeal plexus

  
• Tubal tonsils


  Lymphoid tissue around the opening of the Eustachian (auditory) tube in the lateral wall of the nasopharynx, forming the lateral aspect of Waldeyer's ring

  
• Tubal tonsils


  • Arterial supply chiefly via the ascending pharyngeal artery
  • Venous drainage to the pharyngeal plexus
• Cervical lymph nodes


  Lymph nodes located in the neck, with boundaries defined by the mandible, base of the skull, posterior triangle of the neck, anterior midline structures, clavicle, and manubrium sterni
• Cervical lymph node groups

  • Superficial anterior cervical
  • Superficial lateral cervical
  • Deep cervical
• Superficial anterior cervical lymph nodes

  Located adjacent to the anterior jugular vein, draining lymph from the infrahyoid region, isthmus of the thyroid gland, and inferior larynx, with efferent drainage to the deep lateral cervical lymph nodes

  
• Superficial lateral cervical lymph nodes

  Located adjacent to the external jugular vein, draining lymph from the parotid nodes with efferent drainage to the supraclavicular nodes
• Deep cervical lymph nodes


  All lymphatic vessels from the head and neck drain directly or indirectly into these nodes, with lymph passing to the jugular lymphatic trunk which joins the thoracic duct on the left and forms the right lymphatic duct on the right
• Levels of cervical lymph nodes

  • Level I: Submental and submandibular
  • Level II: Upper jugular (along upper 1/3 of internal jugular vein)
  • Level III: Middle jugular (along middle 1/3 of internal jugular vein)
  • Level IV: Lower jugular (along lower 1/3 of internal jugular vein)
  • Level V: Posterior triangle
  • Level VI: Anterior compartment of the neck (around midline visceral structures)
  • Level VII: Superior mediastinal (extension of paratracheal nodes to brachiocephalic artery level)

  
• Virchow's node


  A supraclavicular lymph node that receives lymph drainage from the abdominal cavity, and its enlargement (Troisier's sign) indicates the presence of abdominal cancer, specifically gastric cancer, that has spread through the lymph vessels

  
• The left jugular lymphatic trunk empties into the thoracic duct, while the right jugular lymphatic duct empties into the right subclavian vein
• The submental lymph nodes are the most likely first site of regional metastasis for a squamous cell carcinoma of the central lower lip, as they drain the central lower lip, floor of the mouth, and apex of the tongue

  
• Lymphatic system functions

  1. Drain tissue fluid, plasma proteins and other cellular debris back into the blood stream

  2. Involved in immune defence
• Lymph


  Collection of substances that enters the lymphatic vessels
• Lymph

  1. Filtered by lymph nodes

  2. Directed into the venous system
• Tonsils (Waldeyer's Ring)

  • Collections of lymphatic tissue within the pharynx
  • Collectively form a ringed arrangement, known as Waldeyer's ring
• Components of Waldeyer's Ring

  • Pharyngeal tonsil
  • Tubal tonsils (x2)
  • Palatine tonsils (x2)
  • Lingual tonsil
• Palatine tonsils


  • Site: between the palatoglossal arch anteriorly and the palatopharyngeal arch posteriorly
  • Laterally: covered by a fibrous capsule
  • Medially (On the pharyngeal side): covered by stratified squamous epithelium
  • Penetrated by 15-20 crypts
• Arterial supply to palatine tonsils

  • Ascending palatine branch of the facial artery
  • Tonsillar branch of the facial artery
  • Ascending pharyngeal branch of the external carotid artery
  • Dorsal lingual branch of the lingual artery
  • Lesser palatine branch of the descending palatine artery
• Venous drainage of palatine tonsils

  To the internal jugular vein via the peritonsillar plexus of lingual and pharyngeal veins
• Lingual tonsil


  • Site: Small round elevations on the most posterior part of the tongue base
  • Responsible for the irregular appearance of the posterior tongue surface
• Arterial supply to lingual tonsil

  • Lingual artery
  • Tonsillar branch of the facial artery
  • Ascending pharyngeal branch of the external carotid artery
• Innervation of lingual tonsil

  Glossopharyngeal nerve
• Pharyngeal tonsils (adenoids)


  • Site: Most superior tonsils that lie in the midline in the roof of the nasopharynx
  • Covering capsule is thinner compared to the palatine tonsils
  • Adenoids have no crypts
• Arterial supply to pharyngeal tonsils

  • Ascending palatine artery
  • Ascending pharyngeal artery
  • Pharyngeal branch of the maxillary artery
  • Artery of the pterygoid canal
  • Basisphenoid artery (branch of the inferior hypophyseal arteries)
  • Tonsillar branch of the facial artery
• Venous drainage of pharyngeal tonsils

  Via numerous small veins which pierce the superior constrictor muscle to empty into the pharyngeal plexus
• Tubal Tonsils


  • Site: Lymphoid tissue around the opening of the Eustachian (auditory) tube in the lateral wall of the nasopharynx
  • Form the lateral aspect of the Waldeyer's ring
• Arterial supply to tubal tonsils

  • Ascending pharyngeal artery
• Venous drainage of tubal tonsils

  To the pharyngeal plexus
• Tonsillitis refers to inflammation of the palatine tonsils
• Tonsillilith (stone in tonsils)
• Cervical Boundaries

  • mandible & base of the skull
  • posterior triangle of the neck
  • anterior midline structures
  • clavicle & manubrium sterni
• Superficial anterior cervical lymph nodes

  • Site: adjacent to the anterior jugular vein
  • Afferent: These nodes drain lymph from the infrahyoid region, isthmus of the thyroid gland, inferior larynx
  • Efferent: deep lateral cervical lymph nodes