Laryngopharynx (Hypopharynx)

What Is the Laryngopharynx?

The laryngopharynx is the lowest section of the pharynx, the muscular tube of the throat, and the point where the airway and the food passage separate. It belongs both to the upper respiratory tract and to the digestive tract. Its name joins "larynx" and "pharynx" because it is the part of the pharynx that lies directly behind the larynx.

Laryngopharynx definition

In anatomy, the laryngopharynx is defined as the part of the pharynx that extends from the upper border of the epiglottis to the lower border of the cricoid cartilage, where it becomes continuous with the esophagus. In front it opens into the larynx through the laryngeal inlet. Doctors often use the name hypopharynx for the same region, especially in ear, nose and throat medicine.

Nasopharynx, oropharynx and laryngopharynx

The pharynx is divided into three parts from top to bottom. The nasopharynx sits behind the nose and carries only air; the oropharynx sits behind the mouth and carries air and food; and the laryngopharynx sits behind the larynx, carrying air and food until they part. A full comparison of the three is on our pharynx page.

Explained simply

Think of the throat as a hallway that splits into two doors at the bottom. The front door leads to the voice box and windpipe, for air. The back door leads to the food pipe, for food and drink. The laryngopharynx is the bottom of the hallway, right in front of those two doors.

Where Is the Laryngopharynx Located?

The laryngopharynx is located in the neck, behind the larynx and in front of the cervical vertebrae, at about the level of the fourth to sixth neck vertebrae in an adult. Its upper limit is the tip of the epiglottis, where it continues from the oropharynx, and its lower limit is the lower edge of the cricoid cartilage, where it narrows into the esophagus.

• In front: the laryngeal inlet, and below it the back surfaces of the arytenoid and cricoid laryngeal cartilages.
• Behind: the prevertebral fascia and the bodies of the cervical vertebrae, separated by the loose retropharyngeal space.
• On each side: the thyroid cartilage and the thyrohyoid membrane, which form the outer walls of the piriform recesses.
• Above: the oropharynx, behind the base of the tongue.
• Below: the esophagus, starting at the upper esophageal sphincter.

Because the larynx rises during swallowing and sits lower in adults than in infants, the exact vertebral level of the laryngopharynx shifts slightly with movement and age.

Laryngopharynx Anatomy: Walls, Recesses and Lining

Laryngopharynx anatomy is usually described in three regions: the paired piriform recesses at the sides, the postcricoid area in front, and the posterior pharyngeal wall behind. These are the same subsites that doctors use when describing the hypopharynx.

Piriform recesses

The piriform recesses (piriform sinuses or fossae) are two pear-shaped gutters, one on each side of the laryngeal inlet. Each is bounded on the inside by the aryepiglottic fold and on the outside by the thyroid cartilage and thyrohyoid membrane. The internal laryngeal nerve runs just under their lining, which is why this area is so sensitive to touch.

Postcricoid area and posterior wall

The postcricoid area is the front wall of the lower laryngopharynx, the mucosa covering the back of the cricoid cartilage down to the start of the esophagus. The posterior wall is the back of the tube, lying in front of the vertebrae. When the pharynx is relaxed, the front and back walls of the lower laryngopharynx lie close together and only open widely during a swallow.

Muscles

The walls are made mostly by the inferior pharyngeal constrictor, which has two parts: the thyropharyngeus, attached to the thyroid cartilage, and the cricopharyngeus, attached to the cricoid cartilage. The cricopharyngeus forms the upper esophageal sphincter, which stays closed between swallows. A weaker triangle between the two parts is called Killian's dehiscence. Longitudinal muscles, such as the palatopharyngeus and stylopharyngeus, lift the pharynx and larynx during swallowing.

Lining, nerves and blood supply

The inner surface is covered by nonkeratinized stratified squamous epithelium, a tough, multilayered lining suited to the friction of swallowed food, unlike the ciliated respiratory epithelium of the nose and larynx. Movement is controlled by the vagus nerve through the pharyngeal plexus, while the internal laryngeal nerve carries sensation from the area around the inlet. Blood comes mainly from branches of the superior and inferior thyroid arteries and the ascending pharyngeal artery.

What Is the Function of the Laryngopharynx?

The function of the laryngopharynx is to carry air into the larynx and to guide swallowed food and liquid into the esophagus without letting them enter the airway. It is a shared passage, so its main task is sorting traffic.

• Breathing: between swallows the laryngeal inlet is open, so inhaled air flows from the oropharynx forward through the laryngopharynx into the larynx and on to the trachea.
• Swallowing: food and liquid are pushed down its walls, around both sides of the closed inlet through the piriform recesses, and into the esophagus.
• Airway protection: its sensitive lining triggers coughing or swallowing if food or fluid touches the inlet; see the cough reflex.
• Voice: as part of the vocal tract above the vocal cords, its shape helps give the voice resonance.

Hypopharynx function during a swallow

During a swallow, breathing stops for a moment, the larynx rises and moves forward, the epiglottis tips down over the inlet and the vocal folds close. At the same time the cricopharyngeus relaxes and the constrictor muscles squeeze from above, so the food is driven past the closed airway into the open esophagus. The whole sequence lasts about a second, and then the airway opens again for the next breath.

Larynx vs Laryngopharynx: What Is the Difference?

The larynx is the voice box, a framework of cartilages that carries air only, while the laryngopharynx is the muscular part of the throat behind it that carries both air and food. They are neighbors: the laryngopharynx wraps around the back and sides of the larynx, and the laryngeal inlet is the doorway between them.

The larynx is lined mostly by ciliated respiratory epithelium and contains the vocal folds, so it produces voice and seals the airway. The laryngopharynx has a stratified squamous lining and no cartilage of its own, and its job is to move food. For the wider comparison of the two organs, see larynx vs pharynx.

How Does the Laryngopharynx Change With Age?

The laryngopharynx is short in infants and becomes longer as the larynx descends in the neck during childhood. In a newborn the larynx sits high in the neck, so the epiglottis can almost touch the soft palate and the laryngopharynx is small.

As the neck grows and the larynx moves down, the laryngopharynx lengthens and the shared space behind the mouth and larynx enlarges. This change makes speech with a full range of sounds possible but also makes the crossing of air and food more complex. In older adults the muscles of swallowing can become weaker and slower, which is one reason swallowing problems become more common with age. Growth of the airway as a whole is described on our respiratory system development page.

Common Conditions That Affect the Laryngopharynx

The laryngopharynx can be affected by infection, stuck foreign bodies, pouches in its wall and, less often, tumors. These are described for education only; more conditions are listed in our respiratory diseases section.

• Pharyngitis: inflammation of the throat lining, often from a viral infection; see pharyngitis.
• Foreign bodies: small sharp objects such as fish bones can lodge in a piriform recess.
• Laryngopharyngeal reflux: stomach contents rising as far as the throat and larynx.
• Zenker's diverticulum: a pouch that bulges out through Killian's dehiscence, mostly in older adults.
• Hypopharyngeal cancer: an uncommon cancer of the lining, most often in the piriform recesses, strongly linked to tobacco and heavy alcohol use.

Persistent trouble swallowing, a lasting sore throat or a feeling of something stuck should be checked by a doctor.