Laryngopharynx

1. Overview

The laryngopharynx, also known as the hypopharynx, is the inferior portion of the pharynx, serving as a shared conduit for both the respiratory and digestive tracts. It functions as a critical crossroad where air from the nasal cavity is directed into the larynx and trachea, and food and fluids are guided into the esophagus. The laryngopharynx plays an essential role in swallowing, breathing coordination, and airway protection.

2. Location

The laryngopharynx is located:

• Posterior to the larynx

• Extending from the superior border of the epiglottis to the inferior border of the cricoid cartilage (around the level of C6 vertebra)

• Continuous inferiorly with the esophagus

It lies anterior to the prevertebral fascia and posterior to the larynx, and it connects superiorly with the oropharynx.

3. Structure

The laryngopharynx is a muscular tube lined by mucosa, and its wall comprises several components:

• Mucosal lining: Stratified squamous epithelium (non-keratinized), suitable for the abrasive nature of swallowed food

• Muscular wall: Includes both circular and longitudinal muscle layers:

  • Inferior pharyngeal constrictor (thyropharyngeus and cricopharyngeus portions)

  • Stylopharyngeus and palatopharyngeus muscles for elevation of the pharynx during swallowing

• Piriform recesses (fossae): Paired mucosal pouches located on either side of the laryngeal inlet, guiding food away from the larynx

It is innervated by the pharyngeal plexus, primarily via the vagus nerve (CN X) for motor function and the glossopharyngeal nerve (CN IX) for sensory input.

4. Function

The laryngopharynx serves several critical functions in both the respiratory and digestive systems:

• Air passage: Conducts air from the oropharynx to the larynx during breathing

• Food passage: Directs swallowed materials from the oropharynx to the esophagus

• Swallowing coordination: Facilitates elevation and closure of the laryngeal inlet to prevent aspiration

5. Physiological Role(s)

In respiratory physiology, the laryngopharynx contributes to:

• Airway routing: Ensures that air enters the larynx while food is directed away from the airway during swallowing

• Protective reflexes: Engages the swallowing reflex and cough reflex to prevent aspiration

• Pressure modulation: Assists in generating intra-abdominal pressure during vocalization, coughing, and Valsalva maneuvers

In swallowing, the laryngopharynx synchronizes with the epiglottis and laryngeal elevation to ensure bolus passage into the esophagus.

6. Clinical Significance

Laryngopharyngeal Reflux (LPR)

A form of acid reflux where gastric contents reach the laryngopharynx. Symptoms may include:

• Chronic throat clearing

• Hoarseness

• Postnasal drip and cough

Unlike GERD, heartburn is often absent. Managed with lifestyle changes, proton pump inhibitors, and voice therapy.

Laryngopharyngeal Cancer

Cancers of the hypopharynx (e.g., in the piriform recess) often present late and may cause:

• Dysphagia (difficulty swallowing)

• Hoarseness or voice changes

• Referred otalgia (ear pain)

Common risk factors include smoking, alcohol, and HPV infection. Diagnosis requires laryngoscopy and biopsy.

Foreign Body Lodgment

The piriform recesses are common sites where food (like fish bones) can become lodged. Symptoms may include:

• Sensation of a foreign object in the throat

• Pain or difficulty swallowing

Removal typically requires endoscopic visualization.

Aspiration Risk

Neurological disorders affecting coordination of the laryngopharynx (e.g., stroke, Parkinson’s disease) can impair swallowing and lead to:

• Silent aspiration

• Recurrent pneumonia

Diagnosis via videofluoroscopic swallow study or fiberoptic endoscopic evaluation of swallowing (FEES).

Cricopharyngeal Dysfunction

Dysfunction or spasm of the cricopharyngeus muscle at the lower end of the laryngopharynx may lead to:

• Oropharyngeal dysphagia

• Zenker’s diverticulum formation

Treatment may involve dilation, botulinum toxin injection, or surgery.