Common carotid artery bifurcation is at -

Ans. is 'a' i.e., Thyroid cartilage o Common carotid artery ends by dividing into internal carotid and external carotid at the upper border of thyroid cartilage at C4 level (thyroid cartilage is at C4 level, its upper border is at C5 level, i.e. C4 C5 disc)Vertebral levels (Mnemonic: All Bifurcations (B14-cation) are at The level of 4)C4Hyoid bone; Bifurcation of common carotid arteryC5Thyroid cartilageC6Cricoid cartilage Trachea beginsOesophagus beginsPharynx and larynx endsC7Thoracic duct reaches its greatest height; Isthmus of thyroid glandT1Sternoclavicular joint; Highest point of apex of lungT2Sternal notchJugular notchT4Sternal angle (of Louis) Junction of superior and inferior mediastinumAscending aorta endsArch of aorta begins and endsBifurcation of tracheaT8IVC hiatusT9Xiphisternal jointT10Oesophageal hiatusT12Aortic hiatus Thoracic duct through diaphragmAzyogos vein through diaphragmLIEnd of spinal cord in adults Transpyloric planePylorus of stomachSuperior mesenteric artery originHilum of kindeys (renal artery-left is above and right is below)Celiac artery originates just above and renal arteries originate just below this line.L2Thoracic duct begins; Azygos and hemiazygos beginL3Umbilicus End of spinal cord in newbornsInferior mesenteric arteryL4iliac crest Aorta bifurcates into common iliac arteriesInferior vena cava formed from common iliac veinsSISacral promontoryS2Posterior superior iliac spine End of dural sac (Dura, arachnoid, subarachnoid space, CSF)Middle of sacroiliac jointS3Posterior inferior iliac spine End of sigmoid colonRectum begins (important landmark in surgery of recto sigmoid carcinoma)