Stylopharyngeus Muscle
Original Editor - Khloud Shreif
Top Contributors - Khloud Shreif and Ewa Jaraczewska
Description
Stylopharyngeus is one of the longitudinal muscles of the pharynx that is important in swallowing. It is paired, thin, long, and cylinder in shape superiorly and flat inferiorly, and one of the three longitudinal pharyngeal muscles.
There can be anatomical variations with stylopharyngeus; these variations, like extra muscle bundles or unusual connections with nearby muscles, may affect how the pharynx moves during swallowing, and can influence the surgical approaches. [1]
Origin
It originates from the medial base of the styloid process of the temporal bone, and is considered the only pharyngeal muscle that has an origin outside the pharyngeal wall.
Then muscle extends inferiorly, traveling along the sides of the pharynx between the superior and middle pharyngeal constrictor muscles. It then spreads out underneath the mucous membrane of the pharynx before finally inserting into three distinct sites. Fibers of the stylopharyngeus may:
- Blend with the other pharyngeal constrictors.
- Join the lateral glossoepiglottic fold.
- Attach to the posterior border of thyroid cartilage after joining the palatopharyngeus muscle. [2]
Insertion
It extends inferiorly from the base of the styloid process between the external and the internal carotid arteries, along the side of the pharynx, then goes deep underneath the mucous membrane of the pharynx, then it can insert in three ways
- Merge with other pharyngeal constrictor muscles (superior, middle, and inferior)
- Join the lateral glossoepiglottic fold.
- Attach to the palatopharyngeus muscle, then attach to the posterior border of the thyroid cartilage. [2]
Nerve
It is innervated by cranial nerve IX (glossopharyngeal nerve).
Artery
It receives arterial blood supply through the pharyngeal branch that comes fromthe ascending pharyngeal artery.
Function
Stylopharyngeus has an effective role in swallowing and speaking; it helps to elevate the pharynx and larynx. When the food once touches the pharyngeal wall, the pharyngeal constrictor muscles push the food toward the esophagus. Then the longitudinal muscle,s including the stylopharyngeu,s come into action to raise the pharynx. [3]
It is considered an upper airway dilator muscle helps to support the lateral pharyngeal wall and maintain upper airway patency. [4]
Clinical relevance
The stylopharyngeus muscle helps to separate different areas in the neck and throat as it helps to form a structure called the stylopharyngeal septum, so it is known as a styloid diaphragm. This landmark helps the surgeons. This septum helps to support both the submandibular and parotid glands, and the surgeons use this as a landmark.
Give easy and safe access to reach the internal carotid artery during surgeries. [5]
In case of injury to cranial nerve IX, the back wall of the upper throat may collapse, causing swallowing problems[3].
In rare cases stylopharyngeal muscle can compress the internal carotid artery, causing symptoms that look like those found with Eagle Syndrome[6] (happens when there is elongation ofthe styloid process) and be obvious with head rotation, and CT can help with this diagnosis.
Assessment
By assessing the swallowing and pharyngeal clearance.
Treatment
If the muscle is affected and not working properly, treatment will focus on the dysfunction that happens.
References
- ↑ Choi DY, Bae JH, Hu KS, Kim HJ. Anatomical variations of the stylopharyngeus and superior constrictors in relation to their function. Anatomy & Cell Biology. 2020 Dec 31;53(4):417-21.
- ↑ 2.0 2.1 Jain P, Rathee M. Anatomy, head and neck, stylopharyngeus muscles. 2023 Jun.
- ↑ 3.0 3.1 Choi DY, Bae JH, Youn KH, Kim HJ, Hu KS. Anatomical considerations of the longitudinal pharyngeal muscles in relation to their function on the internal surface ofthe pharynx. Dysphagia. 2014 Dec;29(6):722-30.
- ↑ Dewald D. Rethinking the muscles of obstructive sleep apnea. CRANIO®. 2022 Sep 3;40(5):389-91.
- ↑ Dallan I, Seccia V, Muscatello L, Lenzi R, Castelnuovo P, Bignami M, Montevecchi F, Tschabitscher M, Vicini C. Transoral endoscopic anatomy of the parapharyngeal space: a step‐by‐step logical approach with surgical considerations. Head & neck. 2011 Apr;33(4):557-61.
- ↑ Piagkou M, Anagnostopoulou S, Kouladouros K, Piagkos G. Eagle's syndrome: a review of the literature. Clin Anat. 2009 Jul;22(5):545-58.