intermammary cleft intermammary cleft the intermammary cleft or intermammary sulcus or sulcus intermammarius is a surface feature of males and females that marks the division of the two breasts with the sternum (breastbone) in the middle. the international federation of associations of anatomists (ifaa) uses the terms "sulcus intermammarius" or "intermammary cleft" when referring to the area between the breasts. intermammary cleftintermammary cleft dividing the breastsdetailsidentifierslatinsulcus intermammariusta98a16.0.02.002ta27110fma55264anatomical terminology etymology "intermammary" ("inter", between + "mamma", breasts + "ry", place) means something that is located or performed between the breasts (example: intermammary intercourse). "sulcus" is a latin word that means a furrow or groove, commonly used to mean a fold, fissure or furrow of the brain (example: lateral sulcus). in popular usage the area is commonly referred to as a cleavage of breasts. in surgical parlance, the cleavage or intermammary cleft is also known as the "medial definition" or "medial fold" of breasts. an imaginary line between the nipples that crosses the intermammary cleft, serving as a landmark for some cpr procedures, is known as the "intermammary line". anatomy deltoid muscle pectoralis major anterior auxiliary fold areola nipple areolar glands serratus anterior inframammary fold manubrium sternum intermammary cleft xyphoid process costal margin polythelia superficial anatomy of human female breast