However, more detailed study is needed to understand the topographic characteristics and anatomical variations of the SC muscle. Moreover, some fibers of the SC muscle are directly attached to the velum, and thus, might assist in retraction thereof. Previous studies have considered the functions of the SC muscle from the perspective of its anatomical morphology: it is attached to the buccinator muscle, which enables a smooth transition from the lingual stage to the pharyngeal stage during ingestion. Their interaction can only be elucidated by observing their topographic relationship on both the inner and outer surfaces of the pharynx. However, the two muscles do not work independently. It is well known that the STP is critically involved in shortening the pharynx and elevating the larynx while the SC muscle plays a critical role as a sphincter muscle. ![]() Thus, there is a particularly close relationship between the STP and the SC muscle. As an exception, the STP arises from the outside of the pharynx (i.e., the styloid process) and penetrates the posterior wall (i.e., the pharyngeal constrictor muscles) into the pharynx. Īlmost all muscles of the pharynx originate and insert into the internal surface of the pharynx. Therefore, a complete understanding of the pharyngeal function requires a detailed knowledge on the morphology of each muscle and relationships between them. These muscles are not simple structures and do not work individually they move and function together in sync. It is well known that three external circular muscles (superior constrictor, middle constrictor, inferior constrictor ) act as the sphincter, and three internal longitudinal muscles (the stylopharyngeus, palatopharyngeus, and salpingopharyngeus) elevate the pharynx. Its development commences between the 4th and 7th week of gestation.The pharynx, a tube-like structure, is a part of the digestive system and is composed of six muscles. Development Įmbryological origin is the third pharyngeal arch. Supernumerary muscles originating from other nearby regions of the skull may be present, and may be clinically significant. The glossopharyngeal nerve runs on the lateral side of this muscle, and crosses over it to reach the tongue. On the lateral pharyngeal wall, it is situated posterior to the superior constrictor muscle, and anterior to the buccopharyngeal fascia. The muscle is situated in between the external carotid artery and internal carotid artery. The stylopharyngeus is the medial-most and most vertical of the three styloid muscles. 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. The stylopharyngeus receives arterial supply from the paryngeal branch of the ascending pharyngeal artery. The stylopharyngeus is the only muscle of the pharynx innervated by the glossopharyngeal nerve (CN IX) (all others being instead innervated by the vagus nerve (CN X)) by special visceral motor neurons with their cell bodies in the rostral part of the nucleus ambiguus. Some of its fibers are lost in the superior and middle constrictor muscles, some merge with the lateral glossoepiglottic fold, while still others join with those of the palatopharyngeus muscle to insert onto the posterior border of the thyroid cartilage. It is the only muscle of the pharynx not to originate in the pharyngeal wall. It arises from (the medial side of the base of) the temporal styloid process. It passes inferior-ward along the side of the pharynx between the superior pharyngeal constrictor (situated deep to the stylopharyngeus) and the middle pharyngeal constrictor (situated superficial to the stylopharyngeus), before spreads out beneath the mucous membrane. It is cylindrical superiorly, and flattened inferiorly. ![]() ![]() The stylopharyngeus is a long, slender, tapered pharyngeal muscle. It acts to elevate the larynx and pharynx, and dilate the pharynx, thus facilitating swallowing. It is innervated by the glossopharyngeal nerve (cranial nerve IX). Some of its fibres insert onto the thyroid cartilage, while others end by intermingling with proximal structures. It originates from the temporal styloid process. The stylopharyngeus muscle is a muscle in the head.
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