Anatomy and Development of Breast (Mammary Gland) Dr. Sama ul Haque

Objectives Describe the gross structure of the breast. Give its blood supply and lymphatic drainage. Discuss the development of breast and its congenital anomalies.

Breast (Mammary Gland) Modified Sweat Glands of the skin Functional in females (Milk secretion) Rudimentary and functionless in males Shape: Hemispherical

Breast (Mammary Gland) Extent: Vertical: 2nd to 6th rib (Base of the breast) Horizontal: Lateral margin of the sternum to the midaxillary line 2/3rd of the breast lies in the superficial fascia (Pectoral fascia) lying on Pectoralis major 1/3rd of the breast lies in the superficial fascia lying on Serratus Anterior

Breast (Mammary Gland) Nipple: Conical or Cylindrical prominence in the center of Areola (Devoid of fat, hair & sweat gland) Surface anatomy: 4th intercostal space lateral to midclavicular line!!!! Areola: Circular pigmented area of the skin surrounding the base of the nipple, containing sebaceous glands Axillary Tail : Small part of the breast extending (of Spence) to the axilla

Breast

Breast

Breast (Mammary Gland) Retromammary Space: Space filled with loose connective tissue between breast and pectoral fascia Each breast consists of 15 to 20 lobules Lactiferous ducts from each lobule open on the summit of the nipple separately Lactiferous duct possesses a dilated Ampulla (Lactiferous sinus) just before its termination

Breast (Mammary Gland) Fibrous septa separates the lobes of the mammary gland Suspensory ligaments (of Cooper): Mammary gland is firmly attached to the dermis of the skin by these fibrous septa forming suspensory ligaments

Breast

Arterial Supply of the Breast Perforating branches (Internal thoracic artery) Lateral thoracic artery (Axillary artery) Thoracoacromial artery (Axillary artery) Intercostal arteries

Arterial Supply of the Breast

Venous Drainage of the Breast

Nerve supply Anterior and lateral cutaneous branches of the 4th – 6th intercostal nerves

Quadrants of the Breast

Lymphatic Drainage of the Breast Lateral quadrants: Anterior Axillary or Pectoral Nodes Medial quadrants: Internal thoracic group of Nodes (Parasternal) Few lymph vessels drains into Posterior intercostal Nodes

Lymphatic Drainage of the Breast Inferior quadrants: May drain into abdominal lymph Nodes Some lymphatic vessels communicate with the lymphatic vessels of the opposite breast

Lymph Drainage of Breast

Comparison of active & inactive phase

Changes in mammary gland

Development of the Breast Modified Sweat glands First appear as bilateral bands of thickened epidermis called the mammary lines (mammary ridges) In the 7th week these lines extends on each side of the body from Forelimb to the region of Hindlimb

Development of the Breast Major part of each mammary lines disappears shortly Small portion of the mammary lines in the thoracic region persists & penetrates the underlying mesenchyme Here it forms 16 to 24 sprouts which in turn give rise to small solid buds

Development of the Breast By the end of prenatal life, the epithelial sprouts canalize and form lactiferous ducts Initially lactiferous ducts open into a small epithelial pit which shortly after birth transformed into nipple At birth lactiferous ducts are devoid of alveoli At puberty alveoli and excretory ducts form due to hormonal changes

Development Anomalies of the Breast Polythelia (Accessary Nipples) Accessary nipples have formed due to the persistence of fragments of the mammary line May develop anywhere along the mammary line but usually appear in the axillary region

Development Anomalies of the Breast Polymastia (Supernumerary breasts) Occurs when a remnant of the mammary line develops into a complete breast Inverted Nipple Lactiferous ducts open in the original epithelial pit that has failed to evert.

Development Anomalies of the Breast

Development Anomaly of the Breast

Gynecomastia Enlargement of breasts in males Causes May be at puberty (Usually regresses) Drugs side effects Prostatic cancer therapy Hormonal imbalance

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