[Location] Localized in the supine position, on the anterior median line of the chest, at the level of the fourth intercostals space, at the midpoint between the two nipples. ( Fig.76 )
[Regional Anatomy] Skin→subcutaneous tissue→the sternal body. There are the anterior cutaneous branches of the fourth intereostals nerve, and the perforating branches of the 4th internal thoracic artery and vein in this area.