Table 1.

Critical structures listed in a head and neck study.

1. Brainstem	13. Carotid vessel (left and right)
2. Brain	14. Cochlea (left and right)
3. Hyoid bone	15. Optic nerves (left and right)
4. Spinal cord	16. Eyes (left and right)
5. Oral cavity	17. Parotid (left and right)
6. Mandible	18. Base of tongue
7. Optic chiasm	19. Supraglottic larynx
8. Lips	20. Postcricioid esophagus
9. Larynx	21. Cervicothoracic esophagus
10. Oropharynx	22. Submandibular glands (left and right)
11. Glottic larynx	23. Pharyngeal constrictor (superior, middle, inferior)
12. Pituitary gland	24. Combined constrictors