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The pharyngeal constrictor 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. The pharyngeal constrictor muscles have multiple variants, with the superior constrictor capable of merging with the middle and inferior constrictor muscles. The pharyngeal muscles receive dual innervation from the glossopharyngeal nerve (ninth cranial nerve or cranial nerve IX) and the vagus nerve (10th cranial nerve or cranial nerve X), facilitating synchronous food propulsion from the oral cavity to the oesophagus. The stylopharyngeus muscle is the only exception, as it is innervated by the glossopharyngeal nerve (CN IX).
| Characteristics | Values |
|---|---|
| Consists of | 3 constrictor muscles: superior, middle, and inferior |
| Muscle function | Constrict to propel food from the oral cavity into the esophagus |
| Muscle contraction | Involuntary |
| Muscle innervation | Glossopharyngeal nerve (CN IX) and vagus nerve (CN X) |
| Muscle innervation exception | Stylopharyngeus muscle is innervated by the glossopharyngeal nerve (CN IX) |
| Muscle supply | Branches of the facial artery |
| Muscle supply exception | Ascending pharyngeal artery, lingual artery, and more |
| Muscle composition | Superior constrictor: originates from the pterygoid process, posterior end of the mandible's mylohyoid line, and the pterygomandibular raphe |
| Middle constrictor: arises from the greater and lesser horns of the hyoid bone and the stylohyoid ligament | |
| Inferior constrictor: arises from the oblique line of the thyroid cartilage and the lateral aspect of the cricoid cartilage |
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What You'll Learn
- The pharyngeal branch of the vagus nerve innervates the constrictor muscles
- The glossopharyngeal nerve innervates the stylopharyngeus muscle
- The cranial nerve IX provides sensory fibres to the upper pharynx
- The recurrent laryngeal nerve provides motor innervation to the cervical oesophagus
- The superior laryngeal nerve mediates afferent fibres for swallowing and belching
The pharyngeal branch of the vagus nerve innervates the constrictor muscles
The pharyngeal muscles are a group of muscles that form the pharynx, which is posterior to the oral cavity. They are divided into an outer circular layer and an inner longitudinal layer. The outer circular layer consists of the superior, middle, and inferior pharyngeal constrictor muscles. These muscles contract during swallowing to propel food from the oral cavity into the oesophagus.
The pharyngeal branch of the vagus nerve innervates the superior, middle, and inferior pharyngeal constrictor muscles. It also innervates the palatopharyngeus and salpingopharyngeus muscles, which are part of the inner longitudinal layer of the pharynx. The stylopharyngeus muscle is the only pharyngeal muscle innervated by the glossopharyngeal nerve (CN IX), also known as the ninth cranial nerve.
Lesions to the pharyngeal branch of the vagus nerve can lead to dysphagia, or difficulty swallowing, due to the involvement of the pharyngeal muscles in this process. The vagus nerve also has clinical applications, such as vagus nerve stimulation, which is used to treat epilepsy and depression.
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The glossopharyngeal nerve innervates the stylopharyngeus muscle
The pharyngeal muscles are a group of muscles that form the pharynx, which is posterior to the oral cavity. They play a dual role as part of both the respiratory and digestive systems, serving as a conduit for air to the larynx and food to the oesophagus. The pharyngeal muscles are organised into an outer circular layer and an inner longitudinal sheet surrounding the lumen. The outer circular layer consists of the superior, middle, and inferior pharyngeal constrictor muscles. The inner longitudinal layer comprises the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles.
The pharyngeal muscles receive dual innervation from the glossopharyngeal nerve (ninth cranial nerve or cranial nerve IX) and the vagus nerve (10th cranial nerve or cranial nerve X). These nerves facilitate synchronous food propulsion from the oral cavity to the oesophagus. The stylopharyngeus muscle is the only pharyngeal muscle innervated by the glossopharyngeal nerve.
The glossopharyngeal nerve provides sensory fibres to the upper pharynx and contributes mucosal membrane sensation in this region. It also directly supplies the oropharyngeal isthmus as it communicates with the lesser palatine nerve (from cranial nerve V2). The glossopharyngeal nerve is also involved in the sensory innervation of the pharyngeal mucosa, contributing to mucosal membrane sensation in the upper pharynx.
The stylopharyngeus muscle is one of the three vertically oriented muscles that aid in swallowing. During swallowing, the stylopharyngeus muscle elevates the pharynx and shortens its length, protecting the airway by sealing off the laryngeal inlet through coordinated movements of the epiglottis and arytenoid cartilages.
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The cranial nerve IX provides sensory fibres to the upper pharynx
The pharynx is a fibromuscular tube that is semicircular in cross-section and situated directly anterior to the vertebral column. It is part of the digestive system, posterior to the oral cavity, larynx, and oronasal cavity. 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 constrictor muscles. These muscles are responsible for the involuntary action of pushing food into the oesophagus.
The pharyngeal muscles receive dual innervation from the glossopharyngeal nerve (ninth cranial nerve or cranial nerve IX) and the vagus nerve (10th cranial nerve or cranial nerve X). The glossopharyngeal nerve provides sensory fibres to the upper pharynx and contributes mucosal membrane sensation in this region. The pharyngeal branch of cranial nerve IX then merges with the pharyngeal branch of the vagus nerve (CN X). The stylopharyngeus muscle is the only pharyngeal muscle innervated by cranial nerve IX.
The inner longitudinal layer consists of the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles. These muscles act to elevate the pharynx and larynx. The palatopharyngeus begins at the posterior hard palate and the palatine aponeurosis, inserting onto the thyroid cartilage. The salpingopharyngeus originates from the auditory tube's inferior aspect and inserts onto the palatopharyngeus muscle. Contraction of this muscle raises the pharynx and opens the auditory tube, equalizing ear pressure during swallowing.
The pharyngeal constrictor muscles have multiple variants. The superior constrictor can merge with the middle and inferior constrictor muscles. The three pharyngeal constrictor muscles are roughly layered circularly on top of one another. They aid in swallowing and help push food bolus down from the oral cavity and into the oesophagus.
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The recurrent laryngeal nerve provides motor innervation to the cervical oesophagus
The pharyngeal constrictor muscles are a group of muscles that form the pharynx, which is posterior to the oral cavity. The pharyngeal muscles push food into the oesophagus. They are divided into two layers: the outer circular layer and the inner longitudinal layer. The outer circular layer consists of the superior, middle, and inferior pharyngeal constrictor muscles. The inner longitudinal layer comprises the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles.
The pharyngeal muscles receive dual innervation from the glossopharyngeal nerve (ninth cranial nerve or cranial nerve IX) and the vagus nerve (10th cranial nerve or cranial nerve X). The stylopharyngeus muscle is the only pharyngeal muscle innervated by cranial nerve IX. The pharyngeal constrictor muscles have multiple variants. The superior constrictor can merge with the middle and inferior constrictor muscles.
The inferior pharyngeal constrictor muscle is the thickest of the three outer pharyngeal muscles. It arises from the sides of the cricoid cartilage and the thyroid cartilage. It is supplied by the vagus nerve (CN X). It is active during swallowing, and partially during breathing and speech. The inferior pharyngeal constrictor muscle may be damaged by chemotherapy-intensity modulated radiotherapy, leading to dysphagia and the continued use of a feeding tube.
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The superior laryngeal nerve mediates afferent fibres for swallowing and belching
The pharyngeal muscles are divided into two layers: the outer circular layer and the inner longitudinal layer. The outer circular layer consists of the superior, middle, and inferior pharyngeal constrictor muscles. These muscles are responsible for propelling food from the oral cavity into the oesophagus during the act of swallowing.
The pharyngeal constrictor muscles receive dual innervation from the glossopharyngeal nerve (ninth cranial nerve or CN IX) and the vagus nerve (tenth cranial nerve or CN X). The vagus nerve has a branch called the superior laryngeal nerve (SLN), which is involved in the activation of swallowing and belching.
The superior laryngeal nerve is a branch of the vagus nerve that provides motor innervation to the cricothyroid muscle of the larynx. It also provides sensory innervation to the epiglottis, tongue, aryepiglittic fold, and larynx. The primary role of the afferents of the SLN is the activation of swallowing. The SLN is not a motor nerve, and its role in controlling esophageal reflexes is sensory in nature.
The SLN mediates all aspects of the pharyngeal swallow. Transection of the SLN blocked the activation of pharyngeal swallowing, as it is the only afferent pathway for the activation of this reflex from the oesophagus. The SLN also mediates the UES contractile reflex (EUCR) and the LES relaxation reflex (ELIR) generated from the proximal oesophagus. However, it does not mediate secondary peristalsis.
The SLN also plays a role in belching. Transection of the SLN did not block the initiation of belching, but it did block one aspect of it, namely the inhibition of the cricopharyngeus EMG. The separate control of UES relaxation by the SLN from the activation pattern of other muscles during belching may explain the variable duration of UES relaxation during this process.
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Frequently asked questions
Constrictor 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.
Circular constrictor muscles are the outer layer of the pharynx. They consist of the superior, middle, and inferior constrictor muscles.
The coordinated movements of the constrictor muscles allow them to propel food smoothly from the oral cavity into the oesophagus.
The circular constrictor muscles are innervated by the pharyngeal branch of the vagus nerve (CN X) with the exception of the stylopharyngeus muscle, which is innervated by the glossopharyngeal nerve (CN IX).
The inferior constrictor muscle is the thickest of the three outer pharyngeal muscles. It arises from the sides of the cricoid cartilage and the thyroid cartilage.
