Carina of trachea Carina of trachea In anatomy, the carina is a ridge of cartilage in the trachea that occurs between the division of the two main bronchi. This occurs at the lower end of the trachea (usually at the level of the 4th thoracic vertebra, which is in line with the sternal angle, but may raise or descend up to two vertebrae higher or lower with breathing). This ridge lies to the left of the midline, and runs antero-posteriorly (front to back). Foreign bodies that fall down the trachea are more likely to enter the right bronchus. The mucous membrane of the
Traditional Chinese medicines derived from the human body were successfully making quasi-empirical preparations of active substances with androgens and estrogens, a technique that modern biochemists did not develop until the early 20th century. The physician William C. Cooper and the sinologist Nathan Sivin (1973) chose what the Chinese call "rényào" 人藥 "human drugs" as a pilot experiment sample for pharmacologically analyzing the efficacy of drugs used in TCM. In contrast to many traditional Chinese plant, animal, and mineral pharmaceuticals with uncertain active constituents, the chemical composition of the human body and parts is well known, and "their therapeutic effectiveness, or lack of it, can be objectively, if approximately,