Bifurcation of trachea is at which level:

The trachea begins in the neck as a continuation of the larynx at the lower border of the cricoid cailage at the level of the sixth cervical veebra.In the cadaver, trachea ends below at the carina by dividing into right and left principal (main) bronchi at the level of the sternal angle (opposite the disc between the fouh and fifth thoracic veebrae).In living subjects, in the erect posture, the bifurcation lies at the lower border of the sixth thoracic veebra.In adults the trachea is about 10-15 cm long and 2 cm in diameter.The fibroelastic tube is kept patent by the presence of U-shaped bars (rings) of hyaline cailage embedded in its wall.The posterior free ends of the cailage are connected by smooth muscle, the trachealis muscle.