Anatomy of the Pharynx: Regions, Muscles, Nerves and Clinical Anatomy
The pharynx is a fibromuscular passage extending from the base of the skull to the lower border of the cricoid cartilage at approximately C6, where it continues as the oesophagus. It conducts air toward the larynx and food toward the oesophagus while contributing to swallowing, speech resonance and immune defence.
Nasopharynx → oropharynx → laryngopharynx. The pharyngeal constrictors propel the bolus downward, while longitudinal muscles elevate and shorten the pharynx during swallowing.
Learning objectives
- Describe the three regions and their boundaries.
- Identify pharyngeal wall layers and muscles.
- Outline sensory, motor, vascular and lymphatic supply.
- Apply anatomy to swallowing, airway protection and common disease.
Regions of the pharynx
| Region | Extent and communications | Important structures |
|---|---|---|
| Nasopharynx | Behind the nasal cavity, from skull base to soft palate; communicates through choanae. | Pharyngeal tonsil, openings of auditory tubes, torus tubarius and pharyngeal recess. |
| Oropharynx | Behind the oral cavity, from soft palate to upper epiglottis; communicates through the oropharyngeal isthmus. | Palatine and lingual tonsils, valleculae, palatoglossal and palatopharyngeal arches. |
| Laryngopharynx | Behind the larynx, from epiglottis to lower cricoid border, then continues as oesophagus. | Laryngeal inlet and piriform fossae, important sites for foreign bodies and tumours. |
Wall of the pharynx
- Mucosa: respiratory epithelium in most of the nasopharynx and stratified squamous epithelium where abrasion by food occurs.
- Pharyngobasilar fascia: fibrous internal support, especially where muscle is deficient superiorly.
- Muscular layer: circular constrictors and longitudinal elevators.
- Buccopharyngeal fascia: external covering separating the pharynx from surrounding spaces.
The retropharyngeal space lies behind the pharynx. Infection may spread through deep neck spaces toward the mediastinum, making retropharyngeal infection clinically important.
Muscles
Circular constrictors
Constricts the upper pharynx; attaches anteriorly around the pterygomandibular region and tongue.
Arises mainly from the hyoid region and overlaps the superior constrictor.
Thyropharyngeus and cricopharyngeus parts narrow the lower pharynx; cricopharyngeus contributes to the upper oesophageal sphincter.
Longitudinal muscles
- Stylopharyngeus: elevates and widens the pharynx; motor supply from glossopharyngeal nerve.
- Palatopharyngeus: elevates pharynx and helps close the nasopharynx.
- Salpingopharyngeus: elevates pharynx and may assist opening the auditory tube.
Most pharyngeal muscles receive motor fibres through the pharyngeal plexus, mainly from the vagus nerve. The notable exception is stylopharyngeus, supplied by CN IX.
Nerve supply
| Function | Main supply |
|---|---|
| Motor | Vagus through pharyngeal plexus; stylopharyngeus by glossopharyngeal nerve. |
| Nasopharyngeal sensation | Maxillary division of trigeminal nerve (V2). |
| Oropharyngeal sensation | Glossopharyngeal nerve (CN IX), important in gag reflex afferent limb. |
| Laryngopharyngeal sensation | Internal laryngeal branch of vagus (CN X). |
The sensory limb is mainly CN IX; the motor response is mainly CN X. The reflex varies among healthy individuals and should be interpreted with other neurological findings.
Blood supply and lymphatics
Arterial supply arises from branches of the external carotid system, including ascending pharyngeal, facial, maxillary and superior thyroid branches. Venous blood drains through the pharyngeal venous plexus into the internal jugular system. Lymph drains to retropharyngeal and deep cervical nodes; this pathway explains cervical lymphadenopathy in pharyngeal infection and malignancy.
Waldeyer’s ring
A ring of lymphoid tissue guards the entrance to the respiratory and digestive tracts. It includes the pharyngeal tonsil, paired tubal tonsils, paired palatine tonsils and lingual tonsil. Enlargement may cause nasal obstruction, sleep-disordered breathing, dysphagia or recurrent infection.
Clinical correlations
- Pharyngitis and tonsillitis: inflammation causes sore throat, odynophagia and cervical nodes.
- Peritonsillar abscess: pus beside the tonsil can cause trismus, muffled voice and uvular deviation.
- Retropharyngeal abscess: may threaten the airway and spread to the mediastinum.
- Piriform fossa foreign body: may injure the internal laryngeal nerve.
- Zenker diverticulum: protrudes through a weak area near the cricopharyngeal region.
- Nasopharyngeal mass: can obstruct the auditory tube and cause unilateral middle-ear effusion.
Link this anatomy to the physiology of swallowing and ENT physical examination.
Key examination points
- The pharynx extends from skull base to C6.
- Its three parts are nasopharynx, oropharynx and laryngopharynx.
- Constrictors propel the bolus; longitudinal muscles elevate the pharynx.
- CN IX supplies stylopharyngeus and much oropharyngeal sensation.
- CN X supplies most other pharyngeal muscles through the pharyngeal plexus.
References and further reading
- NCBI Bookshelf: Anatomy, Head and Neck, Pharynx.
- NCBI Bookshelf: Anatomy, Head and Neck, Laryngopharynx.
For education only. Apply current Uganda Clinical Guidelines, local protocols and specialist advice.
