BREAST/MAMMARY GLAND: It is found in both sexes, but rudimentary in the male. It is a modified sweat gland. It forms an impoant accessory organ of the female reproductive system and provides nutrition to the newborn in the form of milk. SITUATION: The breast lies in the superficial fascia of the pectoralis region. It is divided into 4 quadrants, i.e. upper medial, upper lateral, lower medial, lower lateral. A small extension of the upper lateral quadrant, called the axillary tail of spence, passes through an opening in the deep fascia and lies in the axilla. The opening is called foramen of langer. EXTENT OF BASE: 1)Veically it extends from 2 to 6 th rib. 2)Horizontally it extends from the lateral border of the sternum to the mid-axillary line. DEEP RELATIONS: 1)The breast lies on the deep fascia {pectoral fascia} covering the pectoralis major. 2)Still deeper there are the pas of 3 muscles namely pectoralis major, the serratus anterior, and the external oblique muscle of the abdomen. 3)The breast is separated from the pectoralis fascia by loose areolar tissue, called retromammary space. Because of the presence of this loose tissue, the normal breast can be moved freely over the pectoralis major. BLOOD SUPPLY: It is extremely vascular. supplied by Internal thoracic aery lateral thoracic, superior thoracic and acromiothoracic branches of axillary aery lateral branches of the posterior intercostal aeries. NERVE SUPPLY: anterior and lateral cutaneous branches of the 4th to 6th intercostal nerves. The nerves convey sensory fibres to the skin and autonomic fibres to smooth muscles and to blood vessels. the nerves do not control the secretion of milk. secretion is controlled by hormone prolactin, secreted by pars anterior of the hypophysis cerebri.