Intermammary cleft

The intermammary cleft, 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.

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

Skin At the midline of the breast—the intermammary cleft—a deep layer of superficial fascia (lowermost layer of the skin) is firmly attached to the pectoral fascia (outer side of chest muscles) and the periosteum (bone membrane) of the sternum. It forms a shelving edge that supports the breasts.

Muscles The sternalis muscle is an anatomical variation that lies in front of the sternal end of the pectoralis major runs along the anterior aspect of the body of the sternum. The sternalis muscle often originates from the upper part of the sternum and can display varying insertions such as the pectoral fascia, lower ribs, costal cartilages, rectus sheath, aponeurosis of the abdominal external oblique muscle. There is still a great deal of disagreement about its innervation and its embryonic origin. The sternal side (towards the breastbone) of the pectoralis major is distinct from the clavicular side (towards the collarbone), and the two are separated by a fascial interval. The sternal side is usually more robust and has a fiber orientation that best emulates the downward pull of the subscapularis muscle (armpit muscle).

Ligaments A dense structure of Cooper's ligaments is medially inserted into the skin overlying the sternum, determining the shape of the breasts and intermammary sulcus. These ligaments helpful in supporting the breasts in a youthful disposition; loss of elasticity or attenuation of these ligaments results in ptosis (sagging) of breasts.

Arteries Major blood supply in the area happens through the intermammary artery (also known as the internal thoracic artery) in the thoracic cavity. Among women, this artery is larger. From which anterior perforating branches carry blood into the circummammary arterial plexus, a vascular network formed by branches between minute arteries around the breasts, with lateral mammary branches curving around the lateral border of the pectoralis major.

Lymphs Lymph vessels originating at the base of the nipples can ventrally extend as far as the intermammary cleft and to the opposite breast. The intermammary lymphatics begin as a bunch of small channels consisting of a single layer of epithelium that is supported by stroma tissues. Each mesh of this network surrounds one or more of the ultimate lobules of the glands and receives its lymph from the interacinous spaces between the acini of glands.

Nerves The first intercostal nerve, a tiny branch (ramus) of the anterior division of the first thoracic nerve, runs along the first intercostal space (the lower margin of the first rib), travels towards the sternum to innervate the skin near the midline, and, as the first anterior cutaneous (skin) branch of the thorax, ends on the front of the chest. The nerve supply to sternalis muscles comes from the right third intercostal nerve through its anterior cutaneous branch.

Clinical conditions

Poikiloderma of Civatte Poikiloderma of Civatte, a condition of dilated blood vessels and red to red-brown spots, is common to upper part of the cleavage, especially for those who wear sports bras or push-up bras for prolonged periods, and commonly affects fair skinned middle-aged to elderly women. It is characterized by hypopigmentation, hyperpigmentation, telangiectasias and superficial skin atrophy (occasional itching is reported), is another condition caused by long exposure to sunlight. Poikiloderma and dermatoheliosis are treated by desquamation (skin peeling).

Hidradenitis suppurativa Hidradenitis suppurativa (HS) is a non-contagious chronic skin disease affects intertriginous skin of apocrine sweat gland bearing areas like inframammary fold, and intermammary sulcus. It is characterized by clusters of abscesses, epidermoid cysts, sebaceous cysts, pilonidal cysts. There is no single effective treatment for HS. The recommended treatments include antibiotics, antiandrogens, corticosteroids, ciclosporins, and TNF inhibitors.

Tinea versicolor Tinea versicolor is a condition characterized by pinhead to coin sized eruptions on the body trunk and proximal extremities, often affecting the breast cleavage as a narrow band of lesions. The majority of tinea versicolor is caused by the fungus Malassezia globosa, although Malassezia furfur is responsible for a small number of cases. Topical antifungal medications containing selenium sulfide are often recommended to treat tinea versicolor.

Psoriasis Intermammary cleft can get attacked by plaque type psoriasis, which can in turn can cause erythematosus. Prurigo pigmentosa is a rare skin condition of unknown cause that affects depressed places on chest and back like the intermammary area. It is characterized by the sudden onset of erythematous papules that leave a reticulated hyperpigmentation when they heal. Confluent and reticulated papillomatosis, characterized by asymptomatic, small, red to brown, slightly verrucous papules occurs on upper torso, the cleavage area and back. Granular parakeratosis, though mostly an ailment of the armpit area, is also found on the cleavage.

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