Trachea into left and right main bronchi. The trachea begins level with the sixth cervical vertebra and the carina is found at the level of the fifth thoracic vertebra (T5), opposite the sternal angle and can be positioned up to two vertebrae lower or higher, depending on breathing. The trachea is surrounded by rings of hyaline cartilage; these rings are incomplete and C-shaped. The cricoid cartilage is attached to the first tracheal ring at top of the trachea and acts as the bottom of the larynx. There are fifteen to twenty rings in total, separated by narrow intervals. These reinforce the
Traditional Chinese medicines derived from the human body story, it would seem that those 'who go down to the silkworm room' [who are administratively sentenced to castration] should not be ignorant of this method, so I append it here." In some "Bencao gangmu" contexts concerning human drugs, Li Shizhen would accept the traditional theory but deny the contemporary practice. Under the human breath or "qi" section (52.23, tr. Luo 2003: 4176), Li says a "very effective" method for treating an elderly person who is suffering from cold and deficiency in the lower body is to have a boy or girl blow air through a cloth into the navel.