The fresh cadaver dissections demonstrated dye deposition adjacent to the GPN in the parapharyngeal space in all specimens.īased on our anatomical results in cadavers and healthy volunteers, we submit that successful and safe blockade of the distal GPN at the pharyngeal wall level is technically feasible under US guidance. The middle pharyngeal constrictor originates from the greater cornu and lesser cornu of the hyoid bone, and the stylohyoid ligament. It is smaller than the inferior pharyngeal constrictor muscle. It is one of three pharyngeal constrictor muscles. A 40-year-old woman underwent a thyroidectomy after a diagnosis of thyroid cancer. The middle pharyngeal constrictor is a fan-shaped muscle located in the neck. What nerve innervates the pharyngeal constrictors 1. The mean hyoid bone-to-pharyngeal wall distances were 2.04 (SD, 0.35) cm (right) and 2.07 (SD, 0.35) cm (left). What innervates the superior, middle, and inferior pharyngeal constrictor muscles vagus (CN X). The mean skin-to pharyngeal wall distances in the volunteers were 2.03 (SD, 0.41) cm on the right and 2.02 (SD, 0.45) cm on the left. The median distance between the GPN and the ipsilateral greater horn of the hyoid bone was 2.4 cm (range, 2.3-2.7 cm) on the right and 2.6 cm (range, 2.3-2.9 cm) on the left. The GPN was consistently identified between the stylopharyngeal and middle pharyngeal constrictor muscles in all cadaver specimens. To assess the technical feasibility of a distal GPN block in the parapharyngeal space, unilateral US-guided dye injections were performed in 3 fresh cadavers, followed by dissections. In 40 healthy volunteers (20 men and 20 women median age, 35.5 years ) parapharyngeal sonograms were obtained, saved, and analyzed.
This study presents a proof of concept for a new ultrasound (US)-guided technique, which would block the GPN distally, in the parapharyngeal space, away from the immediate vicinity of high-risk collateral structures.įive cadaver heads were dissected, and the location of the GPN was explored bilaterally. Hyoglossus lingual artery middle constrictor stylohyoid triticeal cartilage.Glossopharyngeal nerve (GPN) blocks are usually performed by topical, intraoral, or peristyloid approaches, which carry significant complication risks due to the proximity of important neurovascular structures. The fiber arrangement suggested that, besides constriction of the pharynx, the ascending and descending fibers of the middle constrictor can act as an elevator muscle, and the irregular attachments could affect the functions of the muscles and vessels. The ascending and descending fibers rarely reached the top of the pharynx and the thyroid cartilage, respectively. Gross anatomy The middle nasal concha consists of the medial surface of the labyrinth of ethmoid which is a thin basal lamella that descends from the undersurface of the cribriform plate and ends in a free, convoluted margin. The three groups were inserted into the pharyngeal raphe, and the descending fibers joined the longitudinal pharyngeal muscles. There are two groups of pharyngeal muscles, the external circular layer and the internal longitudinal layer. Some fibers attached to the hyoglossus, occasionally to the stylohyoid and the posterior belly of the digastric, but seldom to the lingual artery and the triticeal cartilage in the thyrohyoid ligament. The posteroinferior group fanned out from the posterior part of the greater horn, while the middle constrictor arose internally to the hyoglossus some fibers often passed externally, and their fibers sometimes intersected around the lingual artery, which ran between them. The middle group ascended posterosuperiorly from the greater horn and fanned out. The anterosuperior group ascended posterosuperiorly from the ligament and the lesser horn and fanned out. The middle constrictor arose from the stylohyoid ligament and the hyoid bone, and its fibers were divided into three overlapping groups. The gross anatomies of the pharyngeal and neighboring muscles were examined in 41 cadavers. This study investigated the attachments of the middle constrictor to clarify its configuration and re-examine its functions.
Such arrangements make the interrelationships among pharyngeal muscles complicated. The pharyngeal muscles overlap each other and some of their parts have different areas of origin.
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