Question #565

The inferior pharyngeal constrictor is the thickest of the pharyngeal constrictors and can be divided into two separate parts: cricopharyngeus and thyropharyngeus.

Cricopharyngeus arises from the cricoids cartilage and forms a complete circle of muscle which contributes to the upper oesophageal sphincter.

Thyropharyngeus arises from the lamina of the thyroid cartilage and the cornu of the cartilage. Its fibres are oblique running posteriorly and superiorly to meet at the pharyngeal raphe.

Between the two muscles there is a weak area known as Killian’s dehiscence. The unsupported mucosa that lines the pharynx at this point may protrude outwards forming a pharyngeal pouch following a loss of co-ordination between the two component of inferior constrictor.

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