MRCS Part B (OSCE) - Online Resources

The pharynx is a fibromuscular tube extending from the base of the skull to the inferior border of the cricoid cartilage.

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The pharynx is divided into three parts:

1. Nasopharynx (base of skull to soft palate).
2. Oropharynx (soft palate to epiglottis).
3. Laryngopharynx (epiglottis to cricoid cartilage).

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The pharynx is composed of an external circular and an internal longitudinal layer of muscles.

Note: This arrangement is opposite to elsewhere in the alimentary tract.

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The internal longitudinal layer of muscles consists of:

1. Palatopharyngeus
2. Stylopharyngeus
3. Salpingopharyngeus

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The muscles of the internal longitudinal layer elevate the pharynx and larynx during swallowing and speaking.

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The external circular layer of muscles also known as the constrictor muscles of the pharynx consists of:

1. Superior constrictor

• Origin: Pterygoid posterior border, Pterygomandibular raphe.
• Insertion: Median raphe.

1. Middle constrictor

• Origin: Stylohyoid ligament.
• Insertion: Median raphe.

1. Inferior constrictor

• Origin: Thyroid cartilage and cricoid cartilage.
• Insertion: Median raphe.

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"The external constrictors are involved in constricting the wall of the pharynx during swallowing. "

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• Stylopharyngeus
• Salpingopharyngeus
• Palatopharyngeus
• Superior constrictor
• Middle constrictor
• Inferior constrictor

 

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• The membrane between the middle and inferior constrictors is pierced by the internal laryngeal nerve and superior laryngeal vessels. 

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"The recurrent laryngeal nerve and inferior laryngeal vessels pass below the inferior constrictor. "

"A pharyngeal pouch is a pharyngeal diverticulum which occurs through Killian’s dehiscence; an area of weakness in the inferior constrictor muscle of the pharynx between the thyropharyngeus and cricopharyngeus muscles. "

"The clinical symptoms of a pharyngeal pouch include dysphagia, coughing or regurgitation. "

"Barium swallow or endoscopy can be used to confirm the diagnosis. "

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A pharyngeal pouch can be managed in three ways:

• Conservatively (if the patient is asymptomatic or unfit for surgery)
• Endoscopic stapling of the pouch (most common)
• Open/External approach (if endoscopic stapling has failed)

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"The pharyngeal lymphoid ring, also known as the Waldeyer's ring, is an anatomical term collectively describing the annular arrangement of lymphoid tissue in the pharynx. It surrounds the nasopharynx and oropharynx. "

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The pharyngeal lymphoid ring is formed by:

• 2 Palatine tonsils
• 1 Adenoid (nasopharyngeal tonsil)
• 1 Lingual tonsil that is found at the base of the tongue
• 2 Tubal tonsil
• Lateral pharyngeal lymphoid bands

 

The tubal tonsil and lateral pharyngeal lymphoid bands are less prominent compared to the others.

The pharyngeal lymphoid ring are collectively called the nasal-associated lymphoid tissue (NALT).

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"The lymphoid tissue of Waldeyer's ring, located at the origin of the respiratory and alimentary tract, belongs to the mucosa-associated lymphoid tissue (MALT). There main function is antibody production to common environmental antigens. They help in the generation of B cells and plasma cell responses. "