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M01.04.023 The Tonsils (Waldeyer’s Ring)
Tonsils are lymphatic tissue collections located in the pharynx, forming the Waldeyer’s ring. They play a key role in immune defense, serving as the first line of defense against pathogens entering through the nasopharynx or oropharynx.
Components of Waldeyer’s Ring:
- Pharyngeal tonsil (adenoids)
- Tubal tonsils (x2)
- Palatine tonsils (x2)
- Lingual tonsil
These are classified as mucosa-associated lymphoid tissue (MALT) and contain T cells, B cells, and macrophages.
Tonsil Types: Anatomy and Functions
1. Lingual Tonsil
- Location: Posterior third of the tongue, forming the inferior part of Waldeyer’s ring.
- Epithelial Covering: Stratified non-keratinized squamous epithelium.
- Function: Provides immune protection and contributes to the irregular appearance of the posterior tongue.
Blood Supply and Innervation:
| Aspect | Details |
|---|---|
| Arterial Supply | Lingual artery, tonsillar branch of facial artery, ascending pharyngeal artery |
| Venous Drainage | Dorsal lingual vein |
| Innervation | Glossopharyngeal nerve |
Lymphatic Drainage:
- Drains into jugulodigastric and deep cervical lymph nodes.
2. Pharyngeal Tonsil (Adenoids)
- Location: Roof of the nasopharynx, midline.
- Epithelial Covering: Ciliated pseudostratified epithelium.
- Function: Forms the superior aspect of Waldeyer’s ring and provides immune defense.
Blood Supply and Innervation:
| Aspect | Details |
|---|---|
| Arterial Supply | Ascending palatine, ascending pharyngeal, pharyngeal branch of maxillary artery, artery of the pterygoid canal |
| Venous Drainage | Pharyngeal plexus via small veins piercing the superior constrictor muscle |
| Innervation | Vagus and glossopharyngeal nerves |
Lymphatic Drainage:
- Retropharyngeal nodes and deep cervical chain.
3. Tubal Tonsils
- Location: Around the Eustachian tube opening in the nasopharynx lateral wall.
- Epithelial Covering: Ciliated pseudostratified epithelium.
- Function: Forms the lateral aspect of Waldeyer’s ring.
Blood Supply and Innervation:
| Aspect | Details |
|---|---|
| Arterial Supply | Ascending pharyngeal artery |
| Venous Drainage | Pharyngeal plexus |
| Innervation | Maxillary and glossopharyngeal nerves |
Lymphatic Drainage:
- Retropharyngeal and deep cervical lymph nodes.
4. Palatine Tonsils
- Location: Lateral wall of the oropharynx, between the palatoglossal and palatopharyngeal arches.
- Epithelial Covering: Stratified non-keratinized squamous epithelium.
- Function: Most commonly referred to as “the tonsils,” contributing to immune defense.
Blood Supply and Innervation:
| Aspect | Details |
|---|---|
| Arterial Supply | Tonsillar branch of the facial artery |
| Venous Drainage | External palatine vein and pharyngeal plexus |
| Innervation | Maxillary and glossopharyngeal nerves |
Lymphatic Drainage:
- Drains into jugulodigastric and upper deep cervical lymph nodes.
Clinical Relevance
Tonsillitis
- Cause: Usually viral, but bacterial infections account for ~1/3 of cases.
- Symptoms: Painful swallowing, fever, halitosis, swollen and erythematous tonsils with purulent exudate.
- Complication: Peritonsillar abscess (quinsy)—pus collection in the peritonsillar space.
Management of Quinsy:
- Needle aspiration with local anesthetic.
- Incision and drainage with Magill forceps.
Points to Remember
- Tonsils form a protective ring (Waldeyer’s ring) around the pharynx.
- Each tonsil has a unique location, epithelium, blood supply, innervation, and lymphatic drainage.
- Tonsillitis is a common clinical condition affecting the palatine tonsils.
- Complications like quinsy require urgent medical intervention.
Bibliography
- Relevant medical textbooks and anatomy atlases for tonsil anatomy and clinical conditions.
- Recent journal articles on tonsillar diseases and management.