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The pharynx is a muscular tube that is part of the digestive system, located posterior to the oral cavity and the larynx. It is divided into three sections: the oropharynx, nasopharynx, and laryngopharynx. The pharyngeal muscles are organised into two layers: an outer circular layer and an inner longitudinal layer. The outer layer consists of three constrictor muscles: superior, middle, and inferior. The inner layer comprises the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles. These muscles play a crucial role in swallowing, speech, and breathing. They receive dual innervation from the glossopharyngeal and vagus nerves, which facilitate the synchronous propulsion of food from the oral cavity to the oesophagus.
| Characteristics | Values |
|---|---|
| Definition | Pharyngeal muscles are a group of muscles that form the pharynx, which is posterior to the oral cavity, determining the shape of its lumen, and affecting its sound properties as the primary resonating cavity. |
| Function | The pharyngeal muscles (involuntary skeletal) push food into the oesophagus. They also play a role in respiratory stabilization by controlling the size of the pharyngeal airway and regulating its compliance. |
| Location | The pharynx is a muscular tube that is part of the digestive system, located posterior to the oral cavity and larynx. It is divided into three sections: the oropharynx, nasopharynx, and laryngopharynx. |
| Structure | Pharyngeal muscles are organized into two layers: an outer circular layer and an inner longitudinal layer surrounding the lumen. |
| Outer Circular Layer | Consists of three constrictor muscles: superior, middle, and inferior pharyngeal constrictors. |
| Inner Longitudinal Layer | Comprises the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles. |
| Innervation | Pharyngeal muscles receive dual innervation from the glossopharyngeal (CN IX) and vagus (CN X) nerves, facilitating synchronous food propulsion from the oral cavity to the oesophagus. The stylopharyngeus muscle is innervated by CN IX, while the tensor veli palatini is supplied by the mandibular nerve (CN V3). |
| Blood Supply | Branches of the facial artery, including the ascending pharyngeal artery and lingual artery, provide blood supply to the pharyngeal muscles. |
| Pathology | Dysphagia, or difficulty swallowing, may be due to pharyngeal muscle dysmotility. Infections, muscular disorders, and malignancies can impair pharyngeal function. |
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What You'll Learn
- The pharynx is a muscular tube that is part of the digestive system
- The pharyngeal muscles are arranged in two layers
- The pharyngeal constrictor muscles form the outer circular layer
- The inner longitudinal layer comprises the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles
- Pharyngeal muscles are innervated by the glossopharyngeal and vagus nerves
The pharynx is a muscular tube that is part of the digestive system
The pharyngeal muscles are organised into two layers: an outer circular layer and an inner longitudinal layer. The outer layer is made up of three constrictor muscles—superior, middle, and inferior. These muscles contract sequentially from superior to inferior, constricting the pharyngeal lumen and propelling food or liquid into the oesophagus. The superior constrictor muscle originates from the pterygoid process, the posterior end of the mandible's mylohyoid line, and the pterygomandibular raphe. It narrows the upper pharyngeal segment and closes the nasopharynx during swallowing. The middle constrictor muscle arises from the hyoid bone and the stylohyoid ligament, constricting the middle pharyngeal portion during swallowing. The inferior constrictor muscle has two components: thyropharyngeal fibres that originate from the thyroid cartilage, and cricopharyngeal fibres that arise from the cricoid cartilage. Both sets of fibres attach to the median pharyngeal raphe and compress the lower pharynx.
The inner longitudinal layer comprises the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles. These muscles primarily act to elevate the pharynx and larynx. The pharyngeal muscles are innervated by the glossopharyngeal nerve (CN IX) and the vagus nerve (CN X), with the exception of the stylopharyngeus muscle, which is innervated solely by the glossopharyngeal nerve.
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The pharyngeal muscles are arranged in two layers
The pharynx is a fibromuscular tube that is semicircular in cross-section and is situated directly anterior to the vertebral column. It is part of the digestive system, posterior to the oronasal cavity and larynx. The pharyngeal muscles are arranged in two layers, namely an outer circular layer and an inner longitudinal layer.
The outer layer is made up of three pharyngeal constrictor muscles, namely the superior, middle, and inferior pharyngeal constrictors. The superior constrictor originates from the pterygoid process, the posterior end of the mandible's mylohyoid line, and the pterygomandibular raphe. It narrows the upper pharyngeal segment and closes the nasopharynx during swallowing. The middle constrictor arises from the greater and lesser horns of the hyoid bone and the stylohyoid ligament. It constricts the middle pharyngeal portion during swallowing. The inferior constrictor is subdivided into the thyropharyngeus superiorly and the cricopharyngeus inferiorly. The thyropharyngeus originates from the thyroid cartilage, while the cricopharyngeus arises from the cricoid cartilage and merges with the oesophageal muscle. Both segments attach to the median pharyngeal raphe. The inferior constrictor compresses the lower pharynx. The coordinated movements of the constrictor muscles allow them to propel food smoothly from the oral cavity into the oesophagus.
The inner longitudinal layer consists of the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles. The palatopharyngeus originates from the hard palate of the oral cavity and inserts onto the pharyngeal wall. The salpingopharyngeus originates from the Eustachian tube and inserts onto the pharyngeal wall. It also opens the Eustachian tube to equalise the pressure in the middle ear. The stylopharyngeus is the only pharyngeal muscle innervated by the glossopharyngeal nerve (CN IX). It originates from the styloid process of the temporal bone and inserts onto the thyroid cartilage, blending with the fibres of the palatopharyngeus muscle. Contraction of the stylopharyngeus muscle elevates both the pharynx and larynx, aiding in swallowing.
The pharyngeal muscles receive dual innervation from the glossopharyngeal (ninth cranial nerve or CN IX) and vagus (tenth cranial nerve or CN X) nerves. The stylopharyngeus muscle is supplied by the glossopharyngeal nerve, while the tensor veli palatini is supplied by the mandibular nerve (CN V3). The pharyngeal muscles and their corresponding nerves originate from the third and fourth branchial arches. The pharyngeal region receives its arterial supply from branches of the external carotid artery, including the ascending pharyngeal, facial, lingual, and maxillary arteries.
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The pharyngeal constrictor muscles form the outer circular layer
The pharynx is a muscular tube that is part of the digestive system. It is located posterior to the oronasal cavity and larynx. The pharyngeal tube is divided into three sections: the oropharynx, nasopharynx, and laryngopharynx. The pharyngeal muscles are organised into an outer circular layer and an inner longitudinal layer.
The superior constrictor muscle is the uppermost pharyngeal constrictor. It originates from the pterygoid process, the posterior end of the mandible's mylohyoid line, and the pterygomandibular ligament. During swallowing, the superior constrictor narrows the upper pharyngeal segment and closes the nasopharynx.
The middle constrictor muscle arises from the greater and lesser horns of the hyoid bone and the stylohyoid ligament. It constricts the middle pharyngeal portion during swallowing.
The inferior constrictor is the thickest and most developed of the three pharyngeal constrictors. It is subdivided into the thyropharyngeus superiorly and the cricopharyngeus inferiorly. The thyropharyngeus originates from the thyroid cartilage, while the cricopharyngeus arises from the cricoid cartilage and merges with the oesophageal muscle. The inferior constrictor compresses the lower pharynx, facilitating the propulsion of food into the oesophagus.
The coordinated contractions of the pharyngeal constrictor muscles in the outer circular layer are essential for swallowing. They work in a sequential manner, from superior to inferior, to constrict the pharyngeal lumen and propel food downwards.
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The inner longitudinal layer comprises the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles
The oropharynx is a muscular tube that is part of the digestive system, located posterior to the oronasal cavity and larynx. The pharyngeal muscles are organised into two layers: an outer circular layer and an inner longitudinal layer.
The palatopharyngeus muscle is a small, long, fleshy muscle located in the roof of the mouth. It is narrower in the middle and forms an arch with the mucous membrane covering its surface. This muscle pulls the pharynx upward, preventing food from passing into the nasopharynx.
The salpingopharyngeus muscle is absent in about 40% of individuals and is more common in thin people. It receives motor innervation from the pharyngeal plexus of the vagus nerve. During swallowing, it raises the pharynx and larynx, and laterally draws the pharyngeal walls up. It also opens the pharyngeal orifice of the Eustachian tube during swallowing, allowing for pressure equalisation.
The stylopharyngeus muscle originates from the temporal styloid process, with some fibres inserting into the thyroid cartilage. It is the only muscle of the pharynx not to originate in the pharyngeal wall. This muscle elevates and dilates the pharynx, facilitating swallowing. It is innervated by the glossopharyngeal nerve (cranial nerve IX).
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Pharyngeal muscles are innervated by the glossopharyngeal and vagus nerves
The pharynx is a muscular tube that is part of the digestive system, located posterior to the oronasal cavity and larynx. It is divided into three sections: the oropharynx, nasopharynx, and laryngopharynx. The pharyngeal muscles are organised into an outer circular layer and an inner longitudinal layer. The outer layer consists of three constrictor muscles: the superior, middle, and inferior pharyngeal constrictors. These muscles contract sequentially to propel food from the oral cavity into the oesophagus. The inner longitudinal layer includes the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles.
The pharyngeal muscles are innervated by the glossopharyngeal and vagus nerves, also known as the ninth and tenth cranial nerves, respectively. The glossopharyngeal nerve (CN IX) provides sensory fibres to the upper pharynx and contributes to mucosal membrane sensation. It also supplies the stylopharyngeus muscle. The vagus nerve (CN X) provides motor innervation to all the muscles of the pharynx and soft palate, except the stylopharyngeus and tensor veli palatini muscles. The vagus nerve contributes to the general sensory perception of the pharynx.
The pharyngeal plexus, formed by branches of the glossopharyngeal and vagus nerves, plays a crucial role in innervating the pharyngeal muscles. It lies on the posterolateral wall of the pharynx, mainly over the middle pharyngeal constrictor, and acts as the main motor and sensory nerve supply to the muscles of the pharynx and soft palate. The pharyngeal plexus coordinates swallowing and speech, receiving motor fibres from the nucleus ambiguus and sensory fibres from the trigeminal nerve.
Understanding the innervation of pharyngeal muscles is essential for diagnosing and treating speech and swallowing disorders. For example, dysphagia, or difficulty swallowing, may be caused by pharyngeal muscle dysmotility or cricopharyngeal achalasia, where the cricopharyngeal muscle fails to open adequately. Glossopharyngeal neuralgia, characterised by repeated pain episodes in the tongue, throat, ear, and tonsils, is another condition associated with the irritation of the glossopharyngeal nerve (CN IX).
The pharyngeal muscles have complex spatial interrelationships with their innervating branches. Studies have examined the anatomical connections between the muscles and nerves, finding that the pharyngeal muscles overlap each other and occasionally link to adjacent muscles. The precise innervation patterns provide valuable insights for functional diagnosis and understanding postoperative dysphagia.
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Frequently asked questions
Oropharyngeal muscles are part of the pharyngeal muscles, which are a group of muscles that form the pharynx, a muscular tube that is part of the digestive system. The pharynx is located posterior to the oral cavity and the larynx. The oropharyngeal muscles specifically refer to the muscles in the oropharynx, which is one of the three main sections of the pharynx, along with the nasopharynx and laryngopharynx.
Oropharyngeal muscles play a crucial role in swallowing and speech. They contract to propel food from the oral cavity into the oesophagus. Additionally, they contribute to respiratory stabilization by controlling the size of the pharyngeal airway and regulating its compliance.
The oropharyngeal muscles can be categorized into two groups: longitudinal and circular. The longitudinal muscles include the palatopharyngeus, salpingopharyngeus, and stylopharyngeus. These muscles primarily act to elevate the pharynx and larynx. The circular muscles, also known as the pharyngeal constrictor muscles, consist of three layers: superior, middle, and inferior. These muscles contract sequentially to constrict the pharyngeal lumen and facilitate the downward propulsion of food.
Dysphagia is a condition characterized by difficulty swallowing foods or liquids. It can be caused by oropharyngeal muscle dysmotility, which impairs the normal functioning of the oropharyngeal muscles during the swallowing process. This can lead to food accumulation in the pharynx and subsequent issues such as choking, regurgitation, coughing, and pneumonia.
