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Fourth branchial arch muscles

Other Terms: Pharyngeal muscles, Muscles of the pharynx, Palatal muscles, Palatal muscles

Description

Like the stylopharyngeus muscle of the third arch, the muscles of the fourth arch retain their embryonic position in the wall of the pharynx. The muscles are divided into two muscle groups, the three constrictor muscles of the pharynx proper and their anterior extension the cricothyroideus and the muscles of the soft palatal septum at the anterior aspect of the pharynx. The constrictor muscles form a semicircular arch of muscle in the posterior and lateral walls of the pharynx. When they contract they narrow, or constrict, the pharynx and help to initiate the swallowing reflex. The palatal muscles are small slips of muscle that converge posterior to the hard palate to form the muscular substance of the soft palate. The principal function of this musculature is to tense and raise the palate against the roof of the pharynx. This closes the posterior nasal aperture and prevents food and drink from entering the nasal cavity. The vagus nerve is the nerve supply to all of the muscles of the fourth branchial arch.

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