Common carotid aery divides at the level of?

Superior border of thyroid cailage.Common carotid aery ends at the level of upper border of the thyroid cailage by dividing into external & internal carotid aeriesAlso remember the following imp. levelsSternal angle - costal cailage of 2nd rib, T4/T5 IV discXiphoid process - T9Tracheal bifurcation - T4/T5 IV discTrachea extends from - C6 to T5Arch of aoa begins and ends at - T4Aoic opening in diaphragm - T12Esophageal opening in diaphragm - T10Vena caval opening in diaphragm - T8Thoracic duct crosses from Rt to Left - T5Splenic axis - 10th ribCeliac trunk arises - Tl 2/L, IV discSuperior mesenteric aery arises - LIRenal aeries - L1/L2Inferior mesenteric aery - L3Aoa ends by bifurcating into common iliac aeries - L4IVC begins at - L5Umblicus - L3/L4