Pharynx

Q: What are the anterior, posterior, and lateral boundaries of the retropharyngeal space (spatium retropharyngeum)?

The retropharyngeal space (spatium retropharyngeum) is bounded by fascial layers and the pharyngeal wall: Anteriorly: The posterior wall of the pharynx, covered by the visceral layer of the deep cervical fascia (buccopharyngeal fascia).Posteriorly: The prevertebral fascia.Laterally: Alar fascial partitions extending from the pharynx to the vertebral column, separating it from the lateral pharyngeal spaces.

Q: At what vertebral level does the pharynx become the esophagus?

The transition into the esophagus (oesophagus) occurs at the level of the sixth to seventh cervical vertebrae (CVI–CVII).

For medical students2 min readUpdated 2026-10-10

The pharynx is a musculomembranous organ that connects the nasal and oral cavities to the larynx and esophagus. It serves as a common passageway for both food and air, extending from the base of the skull down to the level of the lower cervical vertebrae.

LocationFrom the cranial base to the VI–VII cervical vertebrae

MusclesConstrictors (compress) and elevators of the pharynx

SubdivisionsNasopharynx, oropharynx, and laryngopharynx

TransitionContinues inferiorly into the esophagus (*oesophagus*)

General Structure and Walls

The pharynx is anchored to the base of the skull (from the pharyngeal tubercle to the carotid canals and the sphenoid bone). Its upper part is relatively fixed, while the inferior portion has greater mobility due to loose connective tissue. Posteriorly, the pharynx is adjacent to the vertebral column.

The structural components of the pharynx include:

Pharyngeal fornix (fornix pharyngis);
Anterior, posterior, and lateral walls.

Layers of the Pharyngeal Wall

The wall of the organ is formed by three main layers:

Mucous membrane (tunica mucosa). This is a continuation of the nasal and oral mucosa. In the nasopharynx, it is lined by ciliated pseudostratified columnar epithelium, whereas in the oro- and laryngopharynx, it is lined by non-keratinized stratified squamous epithelium. In the inferior part, it forms longitudinal folds. It contains pharyngeal glands (glandulae pharyngeales) and aggregations of lymphoid tissue.
Submucosa (tela submucosa). Consists of dense connective tissue. Superiorly, it thickens to form the pharyngobasilar fascia (fascia pharyngeobasilaris), while inferiorly it becomes looser.
Muscular layer (tunica muscularis pharyngis). Formed by skeletal (striated) muscle. It includes the constrictors (mm. constrictores pharyngis), which narrow the pharynx, and elevators. In the midline, the fibers of the constrictors intertwine to form the pharyngeal raphe (raphe pharyngis).

Subdivisions of the Pharyngeal Cavity

Anatomically, the pharynx is divided into three parts, each communicating with a specific cavity:

Nasopharynx (pars nasalis pharyngis). Extends from the fornix to the soft palate. It communicates with the nasal cavity via the choanae (choanae). The lateral walls feature the pharyngeal opening of the auditory tube (ostium pharyngeum tubae auditivae), bounded by the torus tubarius (torus tubarius). The pharyngeal tonsil (tonsilla pharyngealis) is located in the region of the fornix.
Oropharynx (pars oralis pharyngis). Lies between the soft palate and the plane of the laryngeal inlet. It communicates with the oral cavity through the faucial isthmus (isthmus faucium). The palatine tonsils (tonsillae palatine) lie within the tonsillar fossae (fossae tonsillares).
Laryngopharynx (pars laryngea pharyngis). Extends to the transition into the esophagus at the level of CVI–CVII. Anteriorly lies the laryngeal inlet (aditus laryngis), and laterally are the piriform fossae (recessus piriformes).

Peripharyngeal Spaces and Blood Supply

Surrounding the pharynx is loose cellular tissue that forms important potential spaces:

Retropharyngeal space (spatium retropharyngeum) — located between the pharynx and the prevertebral fascia, extending down to the mediastinum.
Lateral pharyngeal space (spatium lateropharyngeum) — contains the major neurovascular bundle of the neck.

Innervation is derived from the pharyngeal plexus (plexus pharyngeus), formed by branches of the glossopharyngeal nerve, vagus nerve, and sympathetic fibers. Blood supply is provided by branches of the ascending pharyngeal, facial, maxillary, and superior thyroid arteries. Lymphatic drainage is directed to the cervical lymph nodes.

Mnemonic

The parts of the pharynx are easy to remember from top to bottom by their adjacent structures: Nose → Mouth → Larynx (Nasopharynx, Oropharynx, Laryngopharynx).

Frequently asked questions

Which specific muscles form the muscular layer of the pharynx?

The muscular layer of the pharynx is formed by striated skeletal muscles functionally divided into constrictors (narrowing the lumen) and elevators/dilators. These include:

Superior pharyngeal constrictor (m. constrictor pharyngis superior)
Middle pharyngeal constrictor
Inferior pharyngeal constrictor
Stylopharyngeus muscle (m. stylopharyngeus) — elevator/dilator
Palatopharyngeus muscle (m. palatopharyngeus) — elevator/dilator

Which tonsils form Waldeyer's ring (the pharyngeal lymphoid ring)?

Waldeyer's lymphoid ring consists of several main tonsillar masses situated at the entrance of the pharynx:

Palatine tonsil (tonsilla palatina) — paired.
Tubal tonsil (tonsilla tubaria) — paired.
Pharyngeal tonsil (tonsilla pharyngea) — unpaired.
Lingual tonsil (tonsilla lingualis) — unpaired.

Sometimes an additional laryngeal tonsil located in the ventricle of the larynx is included.

What vessels and nerves are contained within the neurovascular bundle of the neck located in the lateral pharyngeal space?

The neurovascular bundle running in the posterior compartment of the lateral pharyngeal space contains major blood vessels and cranial nerves. These include:

Internal carotid artery
Internal jugular vein
Glossopharyngeal nerve (CN IX)
Vagus nerve (CN X)
Accessory nerve (CN XI)
Hypoglossal nerve (CN XII)

Additionally, the superior cervical sympathetic ganglion is located in this region.

What are the anterior, posterior, and lateral boundaries of the retropharyngeal space (spatium retropharyngeum)?

The retropharyngeal space (spatium retropharyngeum) is bounded by fascial layers and the pharyngeal wall:

Anteriorly: The posterior wall of the pharynx, covered by the visceral layer of the deep cervical fascia (buccopharyngeal fascia).
Posteriorly: The prevertebral fascia.
Laterally: Alar fascial partitions extending from the pharynx to the vertebral column, separating it from the lateral pharyngeal spaces.

At what vertebral level does the pharynx become the esophagus?

The transition into the esophagus (oesophagus) occurs at the level of the sixth to seventh cervical vertebrae (CVI–CVII).

What type of epithelium lines the pharyngeal mucosa?

The nasopharynx is lined by ciliated epithelium, whereas the oral and laryngeal parts are lined by stratified squamous epithelium.

What is the raphe pharyngis?

It is a fibrous median raphe formed posteriorly where the constrictor muscles from both sides interlace in the midline.

Go deeper

Topography of peripharyngeal fascial spaces
Waldeyer's pharyngeal lymphoid ring
Pharyngeal constrictors and elevators
Innervation patterns of the pharyngeal plexus