Lies between the second and the sixth ribs and between the sternal edge and the midaxillary line
Tail of the breast extends into the axilla
Approximately two-thirds of the breast lies over the pectoralis major muscle, and the remaining one-third is superficial to the serratus anterior muscle
Cancerous tumors - irregular, firm, hard, not defined masses that may be fixed or mobile, not usually tender, usually occur after age 50
Fibroadenomas - lobular, ovoid, or round, firm, well defined, seldom tender, usually singular and mobile, occur more commonly between puberty and menopause
Benign breast disease - fibrocystic breast disease, marked by round, elastic, defined, tender and mobile cysts, most common from age 30 to menopause, after which it decreases
A smooth, firm movable disc of glandular tissue that may be seen in one breast in males during puberty for a temporary time, can also be seen during hormonal imbalances, drug abuse, cirrhosis, leukemia and thyrotoxicosis