On each side, the anterior line of attachment of the lateral pharyngeal wall begins superiorly on the posterior edge of the medial pterygoid plate of the sphenoid bone just inferior to where the pharyngotympanic tube lies against this plate. It continues inferiorly along the edge of the medial plate of the pterygoid process and onto the pterygoid hamulus. From this point, the line descends along the pterygomandibular raphe to the mandible where this part of the line terminates.
The pterygomandibular raphe is a linear cord-like connective tissue ligament that spans the distance between the tip of the pterygoid hamulus and a triangular roughening immediately posterior to the third molar on the mandible. It joins a muscle of the lateral pharyngeal wall (superior constrictor) with a muscle of the lateral wall of the oral cavity (buccinator).
The second part of the line of attachment of the lateral pharyngeal wall is related to the hyoid bone. It begins on the lower aspect of the stylohyoid ligament, which connects the tip of the styloid process of the temporal bone to the lesser horn of the hyoid bone. The line continues onto the lesser horn and then turns and runs posteriorly along the entire upper surface of the greater horn of the hyoid where it terminates.
The most inferior and third part of the line of attachment of the lateral pharyngeal wall begins superiorly on the superior tubercle of the thyroid cartilage, and descends along the oblique line to the inferior tubercle.
From the inferior tubercle, the line of attachment continues over the cricothyroid muscle along a tendinous thickening of fascia to the cricoid cartilage where it terminates.
The pharyngeal wall is formed by skeletal muscles and by fascia. Gaps between the muscles are reinforced by the fascia and provide routes for structures to pass through the wall.
The muscles of the pharynx are organized into two groups based on the orientation of muscle fibers.
The constrictor muscles have fibers oriented in a circular direction relative to the pharyngeal wall, whereas the longitudinal muscles have fibers oriented vertically.
The three constrictor muscles on each side are major contributors to the structure of the pharyngeal wall (Fig. 8.202 and Table 8.17) and their names indicate their position—superior, middle, and inferior constrictor muscles. Posteriorly, the muscles from each side are joined together by the pharyngeal raphe. Anteriorly, these muscles attach to bones, cartilages, and ligaments related to the lateral margins of the nasal and oral cavities and the larynx.
The constrictor muscles overlap each other in a fashion resembling the walls of three flower pots stacked one on the other. The inferior constrictors overlap the lower margins of the middle constrictors and, in the same way, the middle constrictors overlap the superior constrictors.
Collectively, the muscles constrict or narrow the pharyngeal cavity.
When the constrictor muscles contract sequentially from top to bottom, as in swallowing, they move a bolus of food through the pharynx and into the esophagus.
All of the constrictors are innervated by the pharyngeal branch of the vagus nerve [X].
The superior constrictor muscles together bracket the upper part of the pharyngeal cavity (Fig. 8.202).
Each muscle is attached anteriorly to the pterygoid hamulus, pterygomandibular raphe, and adjacent bone of the mandible. From these attachments, the muscle fans out posteriorly and joins with its partner muscle from the other side at the pharyngeal raphe.
A special band of muscle (the palatopharyngeal sphincter) originates from the anterolateral surface of the soft palate and circles the inner aspect of the pharyngeal wall, blending with the inner aspect of the superior constrictor.