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The pharyngeal isthmus is a narrowing in the region of the faucial pillars that separates the oral and pharyngeal cavities. The pharyngeal phase of swallowing is involuntary and triggered when the bolus comes into contact with the tonsillar pillars and the pharyngeal wall. The pharyngeal muscles are divided into two groups: the longitudinal and the circular. The circular group includes the superior, middle, and inferior pharyngeal constrictors, which are responsible for propelling the bolus into the oesophagus. The superior pharyngeal constrictor narrows the upper pharyngeal segment and closes the nasopharynx during swallowing. The palatopharyngeus, levator veli palatini, and superior constrictor muscles are also involved in closing the velopharyngeal sphincter during swallowing and speaking.
| Characteristics | Values |
|---|---|
| Muscles that close the pharyngeal isthmus | Palatopharyngeus, levator veli palatini, palatoglossus, tensor veli palatini, and superior constrictor muscles |
| Pharyngeal muscles | Divided into an outer circular layer and an inner longitudinal layer |
| Outer circular layer | Superior, middle, and inferior pharyngeal constrictor muscles |
| Inner longitudinal layer | Palatopharyngeus, salpingopharyngeus, and stylopharyngeus |
| Functions of the pharynx | Swallowing, breathing, and phonation |
| Pharyngeal phase of swallowing | The upper pharynx and soft palate close to seal the nasal cavity as the bolus enters the pharynx |
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What You'll Learn
- The palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles elevate the pharynx and larynx
- The pharyngeal isthmus is closed by the levator veli palatini and palatoglossus muscles
- The pharyngeal phase of swallowing is involuntary and triggered by bolus contact
- The pharyngeal muscles are divided into two groups: longitudinal and circular
- The pharyngeal constrictors compress the pharynx to propel food into the oesophagus
The palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles elevate the pharynx and larynx
The pharynx is a muscular tube that connects the nasal cavities to the larynx and oesophagus. It is part of both the alimentary and respiratory tracts. The pharyngeal muscles can be divided into two groups: longitudinal and circular. The inner longitudinal layer consists of the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles.
The palatopharyngeus muscle originates from the hard palate of the oral cavity and inserts onto the pharyngeal wall. It is innervated by the vagus nerve (CN X). During swallowing, the palatopharyngeus elevates the pharynx superiorly.
The salpingopharyngeus muscle originates from the auditory tube's inferior aspect and inserts onto the palatopharyngeus muscle. It is innervated by the vagus nerve (CN X). During swallowing, the salpingopharyngeus muscle elevates the pharynx and opens the auditory tube, equalising ear pressure.
The stylopharyngeus muscle originates from the styloid process of the temporal bone and inserts onto the pharyngeal wall. Unlike the other pharyngeal muscles, it is innervated by the glossopharyngeal nerve (CN IX). The stylopharyngeus elevates the pharynx and expands it laterally.
The pharyngeal phase of swallowing is involuntary and triggered by bolus contact with the tonsillar pillars and pharyngeal wall. During this process, the upper pharynx and soft palate close to seal the nasal cavity as the bolus enters the pharynx. The pharyngeal muscles contract to propel the bolus to the oesophagus. The larynx elevates, the glottis closes, and respiration ceases to protect the lower airway from aspiration.
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The pharyngeal isthmus is closed by the levator veli palatini and palatoglossus muscles
The pharyngeal isthmus is a narrowing in the region of the faucial pillars that separates the oral and pharyngeal cavities. During the pharyngeal phase of swallowing, the upper pharynx and soft palate close to seal the nasal cavity as the bolus enters the pharynx. The pharyngeal muscles are divided into two groups: the outer circular layer and the inner longitudinal layer. The outer circular layer consists of the superior, middle, and inferior pharyngeal constrictor muscles, which are responsible for propelling the bolus into the oesophagus.
The inner longitudinal layer consists of the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles. These muscles act to elevate the pharynx and larynx. The palatopharyngeus muscle originates from the hard palate of the oral cavity and inserts onto the pharyngeal wall. The salpingopharyngeus muscle originates from the Eustachian tube and inserts onto the pharyngeal wall. The stylopharyngeus muscle originates from the styloid process of the temporal bone and inserts onto the pharyngeal wall.
The levator veli palatini and palatoglossus muscles are part of the palatal group of muscles that act to tense and elevate the soft palate to seal the entrance from the oropharynx to the hypopharynx. The levator veli palatini muscle is anchored to fixed points on the skull, while the palatoglossus muscle is anchored to dynamic insertion points on the tongue. These muscles are active during both oral and nasal breathing, with the levator veli palatini being more active during oral breathing and the palatoglossus during nasal breathing.
During the pharyngeal phase of swallowing, the palatoglossus muscle contributes to the closure of the pharyngeal isthmus by elevating the soft palate and sealing off the nasal cavity. The levator veli palatini muscle also assists in closing the velopharyngeal port, which is a functional group of muscles and tissues that work together to close off the nasopharynx during swallowing and speaking.
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The pharyngeal phase of swallowing is involuntary and triggered by bolus contact
The pharyngeal phase of swallowing is an involuntary process that begins when the bolus reaches the palatoglossal arch. This phase is triggered by the bolus coming into contact with the tonsillar pillars and pharyngeal wall. During this phase, the tongue blocks the oral cavity, and the nasopharynx is sealed off from the oropharynx and laryngopharynx by the elevation of the soft palate and its uvula. The pharynx then receives the bolus after shortening and widening, and the larynx elevates due to the contraction of the pharyngeal muscles. The glottis closes, and respiration ceases to protect the lower airway from aspiration.
The pharyngeal phase serves two primary purposes: directing food into the oesophagus and protecting the airway from aspiration. It is characterised by a wave of coordinated stimuli lasting about a second, ending as the food bolus reaches the upper oesophageal sphincter. The pharyngeal phase is the first irreversible step in the swallowing mechanism.
The pharyngeal phase involves the contraction of the pharyngeal muscles, which are divided into an outer circular layer and an inner longitudinal layer. The outer circular layer consists of three circular pharyngeal constrictor muscles: the superior, middle, and inferior pharyngeal constrictors. These muscles contract sequentially from superior to inferior to constrict the pharyngeal lumen and propel the bolus of food inferiorly into the oesophagus. The superior pharyngeal constrictor narrows the upper pharyngeal segment and closes the nasopharynx during swallowing. The middle constrictor constricts the middle pharyngeal portion during swallowing. The inferior constrictor is subdivided into the thyropharyngeus superiorly and the cricopharyngeus inferiorly, which compresses the lower pharynx.
The inner longitudinal layer consists of the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles. These muscles act to shorten and widen the pharynx and elevate the larynx during swallowing. The palatopharyngeus originates from the posterior hard palate and palatine aponeurosis, inserting onto the thyroid cartilage to elevate the pharynx superiorly during swallowing. The salpingopharyngeus originates from the auditory tube's inferior aspect and inserts onto the palatopharyngeus muscle. The stylopharyngeus is unique among the pharyngeal muscles in that it is innervated by the glossopharyngeal nerve (CN IX) rather than the vagus nerve (CN X).
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The pharyngeal muscles are divided into two groups: longitudinal and circular
The outer circular layer consists of the superior, middle, and inferior pharyngeal constrictor muscles. These muscles are arranged like stacked glasses, forming an incomplete muscular circle around the pharynx. They contract sequentially from superior to inferior to constrict the pharyngeal lumen and propel food from the oral cavity into the oesophagus.
The inner longitudinal layer consists of the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles. These muscles act to shorten and widen the pharynx, and elevate the larynx during swallowing. The stylopharyngeus, for example, originates from the styloid process of the temporal bone and inserts onto the pharyngeal wall. It is the only pharyngeal muscle innervated by the glossopharyngeal nerve.
The pharyngeal muscles receive dual innervation from the glossopharyngeal (ninth cranial nerve or cranial nerve IX) and vagus (10th cranial nerve or cranial nerve X) nerves. This facilitates synchronous food propulsion from the oral cavity to the oesophagus. Infections, muscular disorders, and malignancies can impair pharyngeal function.
The pharyngeal constrictor muscles have multiple variants, and the longitudinal muscle groups may have different insertion points, such as the palatine tonsil, epiglottis, and arytenoids. These variants can alter pharyngeal movements. Several surgical interventions target the pharyngeal muscles, such as in the treatment of obstructive sleep apnea, dysphagia, and pharyngeal tumours.
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The pharyngeal constrictors compress the pharynx to propel food into the oesophagus
The pharyngeal constrictors are a group of muscles that play a crucial role in the process of swallowing, also known as deglutition. The pharynx, a musculomembranous tube located posterior to the oral cavity, is an essential component of the digestive system. It is through the pharynx that food passes from the mouth to the oesophagus.
The pharyngeal constrictors are divided into an outer circular layer and an inner longitudinal layer. The outer circular layer consists of three muscles: the superior, middle, and inferior pharyngeal constrictors. These muscles are arranged like stacked glasses, forming an incomplete muscular circle around the pharynx. During swallowing, these circular muscles contract sequentially from superior to inferior, constricting the pharyngeal lumen and propelling food downwards into the oesophagus.
The superior pharyngeal constrictor, located in the oropharynx, originates from various structures including the pterygomandibular ligament and alveolar process of the mandible. It inserts posteriorly onto the pharyngeal tubercle and the pharyngeal raphe. The middle pharyngeal constrictor, found in the laryngopharynx, originates from the stylohyoid ligament and the horns of the hyoid bone, inserting posteriorly into the pharyngeal raphe.
The inferior pharyngeal constrictor, located in the laryngopharynx, has two components: the thyropharyngeus and the cricopharyngeus. The thyropharyngeus originates from the thyroid cartilage, while the cricopharyngeus arises from the cricoid cartilage. Both sets of fibres insert posteriorly onto the pharyngeal raphe. The coordinated contraction of the inferior constrictor compresses the lower pharynx, facilitating the smooth propulsion of food from the oral cavity into the oesophagus.
The inner longitudinal layer of muscles includes the palatopharyngeus, salpingopharyngeus, and stylopharyngeus. These muscles act to shorten and widen the pharynx, as well as elevate the larynx during swallowing. The palatopharyngeus originates from the hard palate of the oral cavity and inserts onto the pharyngeal wall. The stylopharyngeus, innervated by the glossopharyngeal nerve, originates from the styloid process of the temporal bone and inserts onto the pharyngeal wall. The salpingopharyngeus, meanwhile, originates from the Eustachian tube and inserts onto the pharyngeal wall, contributing to both swallowing and pressure equalisation in the middle ear.
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Frequently asked questions
The pharyngeal isthmus is the narrowing in the region of the faucial pillars that separates the oral and pharyngeal cavities.
The pharyngeal isthmus is involved in the speech function, specifically in producing constrictions of the oropharyngeal isthmus.
The muscles involved in the closing of the pharyngeal isthmus include the palatoglossus, levator veli palatini, tensor veli palatini, and palatopharyngeus muscles.
The levator veli palatini muscle elevates the soft palate, which is important for determining the route of respiration. During swallowing, it helps to close the velopharyngeal sphincter.
The palatopharyngeus muscle elevates the pharynx during swallowing, contributing to the shortening and widening of the pharynx, and elevating the larynx.
