General structure and walls
The pharynx is attached to the base of the skull (from the pharyngeal tubercle to the carotid canals and the sphenoid bone). The upper part of the organ is relatively fixed, while the lower part is more mobile due to loose connective tissue. Along its posterior surface, the pharynx is adjacent to the vertebral column.
The structure of the pharynx comprises:
- Pharyngeal fornix (fornix pharyngis);
- Anterior, posterior, and lateral walls.
Tunics of the pharynx
The wall of the organ is formed by three main layers:
- Mucous membrane (tunica mucosa). It is a continuation of the nasal and oral mucosa. In the nasopharynx, it is lined with ciliated epithelium, whereas in the oro- and laryngopharynx, it is lined with stratified squamous epithelium. In the inferior part, it forms longitudinal folds. It contains glands (glandulae pharyngeales) and aggregations of lymphoid tissue.
- Submucosa (tela submucosa). It consists of dense connective tissue. Superiorly, it thickens to form the pharyngobasilar fascia (fascia pharyngobasilaris), and inferiorly it becomes looser.
- Muscular layer (tunica muscularis pharyngis). It is formed by striated musculature. It includes constrictors (mm. constrictores pharyngis), which compress the pharynx, and elevator muscles. Along the midline, the constrictors interlace to form the pharyngeal raphe (raphe pharyngis).
Parts of the pharyngeal cavity
Anatomically, the pharynx is divided into three parts, each communicating with a specific cavity:
- Nasopharynx (pars nasalis pharyngis). It extends from the fornix to the soft palate. It communicates with the nasal cavity via the choanae (choanae). On the lateral walls, the pharyngeal opening of the auditory tube (ostium pharyngeum tubae auditivae) opens, bounded by the torus tubarius (torus tubarius). The pharyngeal tonsil (tonsilla pharyngealis) is located in the region of the fornix.
- Oropharynx (pars oralis pharyngis). It lies between the soft palate and the entrance to the larynx. It communicates with the oral cavity through the fauces (isthmus faucium). Here, the palatine tonsils (tonsillae palatinae) lie within the tonsillar fossae (fossae tonsillares).
- Laryngopharynx (pars laryngea pharyngis). It extends to the transition into the esophagus at the CVI–CVII level. Anteriorly lies the laryngeal inlet (aditus laryngis), and laterally are the piriform fossae (recessus piriformes).
Peripharyngeal spaces and blood supply
Loose cellular tissue is located around the pharynx, forming important spaces:
- Retropharyngeal space (spatium retropharyngeum) — between the pharynx and the prevertebral fascia, extending to the mediastinum.
- Lateral pharyngeal space (spatium lateropharyngeum) — contains the neurovascular bundle of the neck.
Innervation is derived from the pharyngeal plexus (plexus pharyngeus), formed by branches of the glossopharyngeal and vagus nerves 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.
Briefly: answers to topical questions
Which specific muscles form the muscular coat of the pharynx?
The muscular coat of the pharynx is formed by striated muscles functionally divided into constrictors (which narrow the lumen) and dilators (which elevate the pharynx). These include:
- Superior pharyngeal constrictor (m. constrictor pharyngis superior)
- Middle pharyngeal constrictor
- Inferior pharyngeal constrictor
- Stylopharyngeus muscle (m. stylopharyngeus) — dilator
- Palatopharyngeus muscle (m. palatopharyngeus) — dilator
Which tonsils form the Pirogov-Waldeyer lymphatic ring?
The Pirogov-Waldeyer lymphoepithelial ring consists of six main tonsils located at the entrance to the pharynx and in its walls. The ring includes:
- Palatine tonsil (tonsilla palatina) — paired.
- Tubal tonsil (tonsilla tubaria) — paired.
- Pharyngeal tonsil (tonsilla pharyngea) — unpaired.
- Lingual tonsil (tonsilla lingualis) — unpaired.
Sometimes the laryngeal tonsil, located in the ventricle of the larynx, is additionally included in the ring.
Which vessels and nerves are part of the neurovascular bundle of the neck located in the lateral pharyngeal space?
The neurovascular bundle of the neck passing through the posterior (postdiaphragmatic) part of the lateral pharyngeal space includes major blood vessels and cranial nerves. These are:
- Internal carotid artery
- Internal jugular vein
- Glossopharyngeal nerve (cranial nerve IX)
- Vagus nerve (cranial nerve X)
- Accessory nerve (XI cranial nerve)
- Hypoglossal nerve (cranial nerve XII)
The superior cervical sympathetic ganglion is also located in this space.
What is the retropharyngeal space (spatium retropharyngeum) bounded by anteriorly, posteriorly, and laterally?
The retropharyngeal space (spatium retropharyngeum) is bounded by fasciae and the wall of the pharynx. Its walls are formed by:
- Anteriorly: the posterior wall of the pharynx, covered by the visceral layer of the pretracheal (fourth) cervical fascia.
- Posteriorly: the prevertebral fascia.
- Laterally: pharyngovertebral fascial processes extending from the pharynx to the vertebrae and separating it from the peripharyngeal spaces.
The parts of the pharynx are easy to remember from top to bottom by adjacent organs: Nose → Mouth → Larynx (Nasopharynx, Oropharynx, Laryngopharynx).
Class and exam questions
At what level does the pharynx transition into the esophagus?
The transition into the esophagus (oesophagus) occurs at the level of the sixth and seventh cervical vertebrae (CVI–CVII).
What type of epithelium covers the mucous membrane of the pharynx?
In the nasopharynx — with ciliated epithelium, and in the oral and laryngeal parts — with stratified squamous epithelium.
What is the raphe pharyngis?
This is the pharyngeal raphe, formed along the posterior midline by the fusion of the constrictor muscles from both sides.
What else to study on this topic
- Topography of peripharyngeal fascial spaces
- Pharyngeal lymphoepithelial ring
- Constrictor and elevator muscles of the pharynx
- Features of innervation of the pharyngeal plexus
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