Table 2.

Anatomic borders of constrictors and cricopharyngeal muscles

Muscle	Cranial	Caudal	Anterior	Posterior	Lateral	Medial
Superior PCM	Caudal tip of the pterygoid plates (hamulus)	Lower edge of C2	Hamulus of pterygoid plate; mandibula; base of tongue; pharyngeal lumen	Prevertebral muscle	Medial pterygoid muscle	Pharyngeal lumen
Middle PCM	Upper edge of C3	Lower edge of hyoid bone	Base of tongue; hyoid bone	Prevertebral muscle	Greater horn of hyoid bone	Pharyngeal lumen
Inferior PCM	First slice caudal to the lower edge of hyoid bone	Lower edge of the arythenoid cartilages	Soft tissue of supraglottic/glottic larynx	Prevertebral muscle	Superior horn of thyroid cartilage	Pharyngeal lumen
Cricopharyngeal muscle	First slice caudal to the arytenoid cartilages	Lower edge of the cricoid cartilages	Posterior edge of cricoid cartilage	Prevertebral muscle	Thyroid cartilage, fatty tissue, thyroid gland

C2, second cervical vertebra; C3, third cervical vertebra; PCM, pharyngeal constrictor muscle.