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
The Description of the Human Body The Description of the Human Body The Description of the Human Body () is an unfinished treatise written in 1647 by René Descartes (1596-1650). Descartes felt knowing oneself was particularly useful. This for him included medical knowledge. He hoped to cure and prevent disease, even to slow down aging. René Descartes believed the soul caused conscious thought. The body caused automatic functions like the beating of the heart and digestion he felt. The body was necessary for voluntary movement as well as the will. However, he believed the power to move the body was wrongly imagined to come from the