The pharynx, commonly known as the throat, is a muscular tube extending from the nasal cavity down to the neck, serving as a shared pathway for air and food. The laryngopharynx, also called the hypopharynx, represents the lowest segment of this tube, positioned just above the entrance to the esophagus and larynx. This anatomical region ensures the correct passage of air toward the lungs and food toward the stomach. Coordinated muscular action within the laryngopharynx is fundamental to preventing material from entering the airway during swallowing.
Precise Location and Boundaries
The laryngopharynx is situated directly behind the larynx and is a continuation of the oropharynx above it. Its superior boundary is the upper margin of the epiglottis, a cartilage flap at the base of the tongue. The entire structure extends downward, terminating where it becomes continuous with the esophagus. This inferior border is located at the level of the lower margin of the cricoid cartilage, corresponding to the sixth cervical vertebra (C6).
The posterior wall of the laryngopharynx lies against the cervical vertebrae, spanning approximately from C4 to C6. Laterally, the laryngopharynx is flanked by the thyroid cartilage, which offers protection to the area. This makes the laryngopharynx a small, densely packed anatomical area adjacent to the voice box.
Internal Structure and Key Anatomical Features
The wall of the laryngopharynx is composed of several tissue layers, including an inner mucosal lining, a submucosa, and an outer layer of skeletal muscle. The inner surface is lined with non-keratinized stratified squamous epithelium, a robust tissue suited to withstand the friction of passing food. The muscular layer consists of the pharyngeal constrictor muscles, which are arranged in circular layers.
The inferior pharyngeal constrictor muscle is key to this region, consisting of the thyropharyngeus and the cricopharyngeus. The cricopharyngeus forms the upper esophageal sphincter, which remains contracted to prevent air entry during breathing and stop reflux from the stomach. Key internal landmarks include the piriform sinuses, which are recesses located on either side of the laryngeal opening. These sinuses guide the food bolus around the laryngeal inlet and into the esophagus.
Primary Function: The Route Regulator
The main physiological role of the laryngopharynx is to regulate the passage of swallowed material and inhaled air. This separation is accomplished through the reflexive action of swallowing, known as deglutition. As food or liquid is propelled backward, the soft palate elevates to seal off the nasal cavity, and the larynx moves upward and forward.
This upward motion causes the epiglottis to fold down over the laryngeal opening, blocking the airway to prevent aspiration. During this momentary closure, a brief cessation of breathing, called deglutition apnea, occurs. The food bolus is then directed through the piriform sinuses and into the esophagus. The inferior constrictor muscles contract in a wavelike motion (peristalsis) to propel the material past the cricopharyngeus muscle and into the digestive tract.
Common Health Concerns Related to the Laryngopharynx
When the laryngopharynx’s regulatory mechanisms fail, it becomes susceptible to health issues. One common concern is foreign body obstruction, where small objects, such as fish bones, can become lodged within the piriform sinuses. The funnel shape of this area can trap material, leading to pain or difficulty swallowing.
Another frequent condition is Laryngopharyngeal Reflux (LPR), involving the backward flow of stomach contents, including acid, up into the pharynx and larynx. Unlike typical heartburn, LPR often causes symptoms like chronic throat clearing, hoarseness, and the sensation of a lump in the throat. This region is also a site for hypopharyngeal cancer, an aggressive malignancy, with squamous cell carcinoma being the most prevalent type. Because symptoms like a persistent sore throat or difficulty swallowing can be vague, the disease is often diagnosed late, leading to a poorer prognosis than for other head and neck cancers.