In anatomy, the carina is a  cartilaginous ridge within the trachea that runs antero-posteriorly between the two primary bronchi at the site of the tracheal bifurcation at the lower end of the trachea (usually at the level of the 5th 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. Foreign bodies that fall down the trachea are more likely to enter the right bronchus.