Victor Forge
The pharynx is a fibromuscular tube that is part of the digestive system and facilitates swallowing. The pharyngeal muscles are divided into an outer circular layer and an inner longitudinal layer. The outer layer is made up of three pharyngeal constrictor muscles, while the inner layer consists of the palatopharyngeus, salpingopharyngeus, and stylopharyngeus muscles. These muscles contract involuntarily in a sequence known as peristalsis, which helps push food down from the oral cavity into the oesophagus. The stylopharyngeus, salpingopharyngeus, and palatopharyngeus muscles are responsible for elevating the pharynx during swallowing.
| Characteristics | Values |
|---|---|
| Muscles that activate pharyngeal elevation | Palatopharyngeus, salpingopharyngeus, stylopharyngeus, thyrohyoid, intrinsic muscles of the larynx, infrahyoid, superior constrictor, middle constrictor, inferior constrictor |
| Number of muscles involved in pharyngeal elevation | 9 |
| Number of paired muscles involved in pharyngeal elevation | 6 |
| Innervation | Glossopharyngeal nerve (CN IX), vagus nerve (CN X), spinal accessory nerve (CN XI), recurrent laryngeal nerve, pharyngeal plexus |
| Function | Swallowing, breathing, prevention of aspiration, speaking, controlling the size of the pharyngeal airway, regulating compliance |
| Layers | Outer circular layer, inner longitudinal layer |
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What You'll Learn
Stylopharyngeus muscle
The stylopharyngeus muscle is a long, slender, tapered pharyngeal muscle that facilitates swallowing. It is cylindrical superiorly and flattened inferiorly. It is the only muscle of the pharynx not to originate in the pharyngeal wall, instead originating from the medial aspect of the base of the styloid process of the temporal bone. It is innervated by the glossopharyngeal nerve (cranial nerve IX), which is special visceral motor neurons with their cell bodies in the rostral part of the nucleus ambiguus.
The stylopharyngeus muscle is one of three longitudinal pharyngeal muscles, the others being the palatopharyngeus and salpingopharyngeus muscles. All three are located internally to the circular pharyngeal constrictor muscles. The stylopharyngeus muscle extends between the styloid process and several structures of the pharynx and larynx. It runs in a downward direction between the external and internal carotid arteries, and passes between the superior pharyngeal constrictor (laterally) and the middle pharyngeal constrictor (medially).
The stylopharyngeus muscle acts to elevate the larynx and pharynx, and dilate the pharynx. This movement allows the passage of a large food bolus, thereby facilitating swallowing. Elevation of the pharynx causes compression of the lateral laryngeal walls, which further leads to the compression of the pharynx over the food bolus during deglutition. The stylopharyngeus muscle also acts to prevent the dynamic collapse of the dorsal wall of the nasopharynx by supporting the wall during inspiration.
The stylopharyngeus muscle receives arterial supply from the pharyngeal branch of the ascending pharyngeal artery, which stems from the external carotid artery. The lymphatic drainage of the region of the stylopharyngeus muscle is mediated by the middle cervical lymph nodes that drain into the supraclavicular lymph nodes.
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Salpingopharyngeus muscle
The salpingopharyngeus muscle is a longitudinal muscle that forms part of the muscular wall of the pharynx. It is one of three muscles that constitute the inner longitudinal layer of the pharynx, the other two being the palatopharyngeus and stylopharyngeus muscles.
The salpingopharyngeus originates from the auditory tube and inserts onto the palatopharyngeus muscle. The muscle is innervated by branches of the pharyngeal plexus that carry the fibres from the vagus nerve (CN X). It receives arterial supply from the ascending palatine artery, greater palatine artery, and the pharyngeal branch of the ascending pharyngeal artery.
The salpingopharyngeus muscle has several important functions. Firstly, it aids in swallowing by elevating the pharynx and widening its lumen, which facilitates the passage of food. This elevation of the pharynx also occurs during speech, helping to shorten and widen the pharynx. Secondly, the salpingopharyngeus muscle assists in equalizing pressure between the middle ear and the external environment. It does this by opening the auditory (Eustachian) tube, which helps to regulate air pressure and maintain auditory tube function.
The salpingopharyngeus muscle is absent in about 40% of individuals and is more commonly found in thin individuals.
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Palatopharyngeus muscle
The palatopharyngeus muscle is a small, longitudinal muscle that extends from the palate to the pharynx. It is a long, fleshy fasciculus, narrower in the middle than at either end. It originates from the soft palate, where it is divided into two fasciculi by the levator veli palatini and musculus uvulae. The anterior fasciculus is thicker and lies in the soft palate between the levator and tensor veli palatini muscles. The posterior fasciculus lies in contact with the mucous membrane and joins with the opposite muscle in the middle line.
The palatopharyngeus muscle is part of the inner longitudinal layer of the pharynx, which also includes the salpingopharyngeus and stylopharyngeus muscles. This layer of muscles primarily acts to elevate the pharynx and larynx. The palatopharyngeus muscle elevates the pharynx superiorly, anteriorly, and medially during swallowing. This action helps to close the laryngeal airway and prevent food from entering the airway.
The palatopharyngeus muscle also assists in deglutition, or the process of swallowing. It shortens the pharynx and elevates it, closing off the nasopharynx during swallowing. This prevents food from passing into the nasopharynx and directs it towards the lower part of the pharynx.
The palatopharyngeus muscle is innervated by branches of the pharyngeal plexus, which receives input from the vagus nerve (CN X). It is supplied by the ascending palatine branch of the facial artery, the greater palatine branch of the maxillary artery, and the pharyngeal branch of the ascending pharyngeal artery.
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Superior, middle and inferior pharyngeal constrictor muscles
The pharynx is a musculomembranous tube located posterior to the oronasal cavity, extending from the skull base to the cricoid cartilage anteriorly and the inferior C6 margin posteriorly. The pharyngeal muscles are arranged in layers, with the outer circular layer consisting of the superior, middle, and inferior pharyngeal constrictor muscles. These three muscles form a muscular sleeve that has a strong internal lining on its fascial aspect known as the pharyngobasilar fascia.
The superior constrictor muscle originates from the pterygoid process, the posterior end of the mandible's mylohyoid line, and the pterygomandibular raphe. It inserts onto the pharyngeal tubercle of the skull base and the pharyngeal raphe, a midline tendinous seam where the constrictor muscles converge. The superior constrictor muscle also merges with the middle and inferior constrictor muscles.
The middle constrictor muscle arises from the greater and lesser horns of the hyoid bone and the stylohyoid ligament. It inserts onto the median pharyngeal raphe, blending with superior and inferior constrictor fibres. This muscle constricts the middle pharyngeal portion during swallowing.
The inferior constrictor muscle is composed of two parts: the thyropharyngeal part and the cricopharyngeal part. The thyropharyngeal part arises from the thyroid cartilage, while the cricopharyngeal part arises from the cricoid cartilage. The inferior constrictor muscle is the thickest of the three outer pharyngeal muscles and is active during swallowing, breathing, and speech. It constricts the lower portion of the pharynx, elevating it to close off the nasopharynx during swallowing.
The pharyngeal constrictor muscles contract involuntarily in a sequence known as peristalsis, which helps push food from the oral cavity into the oesophagus during and immediately after swallowing.
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Pharyngeal plexus and accessory nerve
The pharyngeal plexus is a nerve plexus located on the outer surface of the pharynx. It is formed by the pharyngeal branches from the vagus nerve (cranial nerve X), the glossopharyngeal nerve (cranial nerve IX), and the cervical sympathetic nerves. The pharyngeal plexus provides motor, sensory, and sympathetic innervation to most of the pharyngeal muscles. The pharyngeal plexus also provides sensory innervation to the oropharynx and laryngopharynx from CN IX and CN X. The pharyngeal plexus acts to coordinate swallowing and speech.
The pharyngeal plexus innervates all the muscles of the pharynx, except the stylopharyngeus muscle, which is innervated directly by a branch of CN IX. The pharyngeal plexus sends branches between the middle and inferior constrictors and between the superior and middle constrictors. The pharyngeal plexus innervates the following muscles:
- Superior pharyngeal constrictor
- Middle pharyngeal constrictor
- Inferior pharyngeal constrictor
- Palatopharyngeus
- Salpingopharyngeus
- Levator veli palatini
- Palatoglossus
- Musculus uvulae
The stylopharyngeus muscle is the only pharyngeal muscle innervated by cranial nerve IX. The stylopharyngeus muscle 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.
The spinal accessory nerve (CN XI) innervates the muscular pharynx, whose superior, middle, and inferior constrictor muscles constitute its external circular layer and work together to transport a bolus of food towards the oesophagus during swallowing.
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Frequently asked questions
The pharyngeal constrictor muscles are three muscles that make up the outer layer of the pharyngeal wall. They are the superior, middle, and inferior pharyngeal constrictor muscles.
The pharyngeal constrictor muscles work together to transport food from the oral cavity to the oesophagus during swallowing.
The stylopharyngeus muscle, a pharyngeal constrictor muscle, elevates the pharynx and expands it laterally.
The salpingopharyngeus and palatopharyngeus muscles, along with the stylopharyngeus, make up the inner longitudinal layer of the pharynx and are involved in pharyngeal elevation.
These three muscles elevate and shorten the pharynx during swallowing, aiding in the process by creating a negative pressure to propel the food downwards.
