Indian Journal of Public Health Research & Development

Internal Thoracic Artery (ITA), also called as Internal Mammary Artery (IMA), arises from the inferior aspect of the first part of the subclavian artery, opposite to the origin of thyro-cervical trunk. It descends vertically 1cm away from the lateral border of the sternum and terminates in 6^th intercostal space dividing into musculophrenic and superior epigastric arteries. As Internal Thoracic Artery is most commonly used as cardiac conduit (graft) to bypass occluded or nearly occluded coronary arterial segments in coronary arterial bypass graft (CABG) surgery, cardiac surgeons should know the possible variations pertaining to its origin, length, course, branches, termination and diameter at various intercostal spaces, to choose the level for bypass.

As per dissection procedure given in Cunningham's 15^th edition vol-02, anterior thoracic cage was separated in 25 cadavers. Study on internal thoracic arteries carried out by painting arteries. In 84% the arteries were taking origin from I-part of Subclavian artery,10% from throcervical trunk, 4% from suprascapular and transverse cervical artery. 2% arising from suprascapular artery alone, in 88% it is getting terminated at 6th intercostals space, 10% in 5^th intercostals space and 2% in 4th intercostals space and mean length 18 cms on right side, 18.30cms on left side.