Pharynx, Cervical Trachea & Cervical Esophagus Flashcards
Dissection: Constrictors of the Pharynx and the structures passing between them [5-minute video]
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State the extents of the pharynx.
From the base of the skull to the inferior border of the cricoid cartilage at approximately the level of C6 vertebra.
[Diagram]
State the posterior, anterior, and lateral boundaries and relations of the pharynx.
Posterior: Prevertebral fascia in front of cervical spine. The pharynx is separated from prevertebral fascia only by a layer of loose areolar tissue, which allows the pharynx to slide freely on this fascia during swallowing.
Anterior: Opens into nasal cavities, mouth and larynx.
Lateral: Neurovascular bundle of neck and styloid process with its attached muscles and ligaments.
List the three parts of the pharynx, from above downwards.
- Nasopharynx, lying behind the nose
- Oropharynx, lying behind the oral cavity
- Laryngopharynx, lying behind the larynx
- [Diagram]
The nasopharynx (also called post nasal space) lies behind the nasal cavities and above the soft palate. State the boundaries of the nasopharynx.
Roof: It is formed by: [Diagram]
(a) Body of sphenoid
(b) Basilar part of the occipital bone
Floor: It is formed by:
(a) Soft palate (sloping upper surface)
(b) Pharyngeal isthmus, an opening in the floor between the free edges of soft palate and posterior pharyngeal wall
Anterior wall: It is formed by posterior nasal apertures (choanae) separated by the posterior edge of nasal septum.
Posterior wall: It forms continuous sloping surface with roof. It is supported by anterior arch of C1 vertebra.
Lateral wall: Pharyngeal opening of the auditory tube, medial pterygoid plate of sphenoid
There are 3 features seen in the nasopharynx. Name them.
(a) Nasopharyngeal (pharyngeal) tonsil
(b) Orifice of the pharyngotympanic/auditory/Eustachian tube
(c) Pharyngeal recess: It is a deep depression behind the tubal elevation; it is also known as the fossa of Rosenmüller. [Graveyard of nasopharynx]
[Diagram]
The pharyngeal tonsil is a collection of lymphoid tissue beneath the mucous membrane at the junction of the roof and posterior wall of the nasopharynx. Briefly discuss the nasopharyngeal bursa (pouch of Luschka), and the remains of the Rathke’s pouch.
✓ Nasopharyngeal bursa/pouch of Luschka: a mucous diverticulum extending upwards into the substance of pharyngeal tonsil from its apex. It is provided with mucous glands.
✓ Sometimes a small dimple is seen in the mucous membrane above the pharyngeal tonsil. It represents the remains of Rathke’s pouch. A craniopharyngioma may arise from it.
[Diagram]: The 4 tonsils i.e. pharyngeal, tubal, lingual, palatine
[Diagram]: Nasopharynx showing positions of these features
[Diagram]: Nasopharyngeal bursa
The upper and posterior margins of the opening of auditory tube are bounded by a tubal elevation known as torus tubarius, which is produced by the collection of lymphoid tissue called tubal tonsil. Two mucous folds extend from the tubal elevation. State these folds.
(i) Salpingopharyngeal fold extends vertically downwards and fades on the side wall of the pharynx. It contains salpingopharyngeus muscle.
(ii) Salpingopalatine fold extends downwards and forwards to the soft palate. It contains the levator palati muscle.
[Diagram: Tubal Tonsils]
[Image: Tubal Tonsils]
State the clinical features of children affected with adenoids (enlargement of the pharyngeal tonsils).
✓ Nasal obstruction
✓ Nasal discharge
✓ Mouth breathing with protrusion of tongue
✓ Toneless voice (due to absence of nasal tone)
✓ Epistaxis (i.e., nose-bleeding).
(Adenoid facis)
State the boundaries of the oropharynx. [It extends from the lower surface of the soft palate above to the upper border of epiglottis below.]
Roof: It is formed by:
(a) Soft palate (under surface).
(b) Pharyngeal isthmus through which it communicates with the nasopharynx.
Floor: It is formed by:
(a) Posterior 1/3rd of the tongue.
(b) Interval between the tongue and epiglottis.
Anterior wall: It is incomplete and formed by:
(a) Oropharyngeal isthmus (through which it opens into the oral cavity).
(b) Pharyngeal part of the tongue.
Posterior wall: It is formed by body of C2 vertebra and upper part of the body of C3 vertebra.
Lateral wall: On each side, it is supported by pterygomandibular raphe, mandible, tongue, and hyoid bone.
The oropharynx provides common path for the food and air.
State the features present in the anterior wall of the oropharynx.
(i) Lingual tonsil, formed by numerous nodules of lymphoid tissue underneath the mucous lining of the pharyngeal part of the dorsum of the tongue.
(ii) Upper free end of epiglottis, behind the tongue.
(iii) Median and lateral glossoepiglottic folds, connecting the anterior surface and edges of the epiglottis, respectively to the tongue.
(iv) Epiglottic valleculae are shallow fossae between the median and lateral glossoepiglottic folds. (Called graveyard of oropharynx because it’s hidden)
[Diagram]: Features of anterior wall of the oropharynx
State the clinical correlation regarding crossing of pathways for food and air in the oropharynx.
Food may sometimes enter into the respiratory tract and cause choking. Similarly the air often enters the digestive tract producing gas in the stomach, which results in eructation (belching).
The laryngopharynx lies behind the laryngeal inlet and posterior wall of the larynx. It lies behind the larynx and extends from the upper border of the epiglottis to the lower border of cricoid cartilage anteriorly and lower border of C6 vertebra posteriorly. State the boundaries of the laryngopharynx.
Anterior wall: It is formed by:
(a) Laryngeal inlet
(b) Posterior surface of the larynx
Posterior wall: It is supported by the bodies of C3, C4, C5, and C6 vertebrae.
Lateral wall: It is supported by thyroid cartilage and thyrohyoid membrane.
[Diagram]
State the features seen in the laryngopharynx.
(a) Anterior wall presents laryngeal inlet and below the inlet it is supported by cricoid and arytenoid cartilages.
(b) Lateral wall presents piriform fossa one on each side of laryngeal inlet.
The piriform fossa is a deep recess broad above and narrow below in the anterior part of lateral wall of the laryngopharynx, on each side of the laryngeal inlet. State its boundaries.
Medial: Aryepiglottic fold and quadrangular membrane of larynx.
Lateral: Mucous membrane covering the medial surface of the lamina of thyroid cartilage and thyrohyoid membrane.
Above: Piriform fossa is separated from epiglottic vallecula by lateral glossoepiglottic fold.
[Diagram 1] Diagram 2]
✓ The internal laryngeal nerve and superior laryngeal vessels pierce the thyrohyoid membrane and traverse underneath the mucous membrane of the floor of the fossa to reach the medial wall. [Diagram showing this]
✓ The piriform fossae form channels that direct solids and liquids from the oral cavity around the raised laryngeal inlet and into the oesophagus.
Fun fact:
The piriform fossa is sometimes artificially deepened by smugglers using lead balls to hide precious materials such as diamonds. For this reason, the piriform fossa is also called smuggler’s fossa.
State the clinical relevance of the piriform fossae.
⚚ The piriform fossae are dangerous sites for perforation by an endoscope as the internal laryngeal nerve may be damaged.
⚚ A malignant tumor of the laryngopharynx (hypopharynx) may grow in the space provided by the piriform fossa without producing symptoms until the patient presents with metastatic lymphadenopathy.
⚚ Ingested foreign bodies (for example, fish bones, safety pins) are sometimes lodged into the piriform fossa. If care is not taken, the removal of foreign bodies may damage the internal laryngeal nerve leading to anesthesia in the supraglottic part of the larynx and subsequent loss of protective cough reflex.