Borders and topographic relations of the cricoid area.

The topography of the cricoid area (CA) of the subglottic larynx was studied in serial plastinated sections of 21 normal adult specimens. The cricoid area was seen to contain adipose tissue and blood vessels and was located between the internal perichondrium of the cricoid cartilage and a medial and lateral fiber layer of the conus elasticus. The lateral fiber layer was pierced by numerous blood vessels cranially and ventrally, providing connections of the CA with neighboring laryngeal areas and the anterior extralaryngeal region. Dorsocranially, the CA continued into the adipose tissue surrounding the cricoarytenoid joint and was adjacent to early ossifying regions of the cricoid lamina. Caudally, the CA was occasionally connected to the extralaryngeal area by projections of adipose tissue piercing the cricotracheal ligament. As shown previously, the relationship of the CA with adjacent anatomical regions facilitates certain growth patterns of subglottic cancer.