Table 1 Anatomic borders of the SWOARs.

From: Radiation-induced late dysphagia after intensity-modulated radiotherapy in nasopharyngeal carcinoma patients: a dose-volume effect analysis

SWOARs

Cranial

Caudal

Anterior

Posterior

Lateral

SCM

Caudal tip of the pterygoid plate

Lower edge of second cervical vertebra

Pterygoid plate or the base of tongue

Prevertebral muscle

Medial pterygoid muscle

MCM

Upper edge of third cervical vertebra

Lower edge of hyoid bone

Base of tongue or the hyoid bone

Prevertebral muscle

Greater horn of the hyoid bone

ICM

Below the lower edge of hyoid bone

Lower edge of arytenoid cartilage

Soft tissue of larynx

Prevertebral muscle

Superior horn of thyroid cartilage

CPM

Below the lower edge of arytenoid cartilage

Lower edge of cricoid cartilage

Posterior margin of the cricoid cartilage

Prevertebral muscle

Thyroid cartilage, soft tissue or thyroid gland

EIM

Below the lower edge of cricoid cartilage

1 cm caudal to esophagus inlet

Posterior margin of the trachea

Prevertebral muscle

Soft tissue or the thyroid gland

  1. Abbreviations: SCM: the superior constrictor muscle, MCM: the middle constrictor muscle, ICM: the inferior constrictor muscle, CPM: cricopharyngeus muscle, EIM: esophagus inlet muscle, cm = centimeter.
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