prebronchial

from The Century Dictionary.

• Situated in advance of the bronchi: as, the prebronchial air-sacs of birds.
• noun A prebronchial process; specifically, one of a pair of air-sacs which lie in front of the windpipe in birds.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (Anat.) Situated in front of the bronchus; -- applied especially to an air sac on either side of the esophagus of birds.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective anatomy Situated in front of the bronchus; applied especially to an air sac on either side of the esophagus of birds.