The inferior arcuate line of the vocal cord marks the cranial border whilst the lower margin of the cricoid cartilage marks the caudal border of the subglottis 1. The inferior arcuate line is defined histologically as the transition point between the squamous epithelium of the true vocal cord and the respiratory epithelium of the subglottis, ~5 mm caudal to the free margin of the true vocal cords 2. The subglottis enlarges in diameter as it progresses caudally following the cricovocal membrane to its origin at the cricoid cartilage which encircles the subglottis at its most caudal extent.
- 1. Kutta H, Steven P, Paulsen F. Anatomical definition of the subglottic region. Cells Tissues Organs (Print). 2006;184 (3-4): 205-14. doi:10.1159/000099628 - Pubmed citation
- 2. Souza D, Al. CE. Textbook Of The Ear, Nose And Throat. Orient Blackswan. (1995) ISBN:8125002758. Read it at Google Books - Find it at Amazon