Location/Anatomic Boundaries
The axilla is a pyramidal space between the arm and the thoracic wall. It contains the axillary vessels and their branches, the brachial plexus and its…

The thoracic wall is composed of the 12 thoracic vertebra, 12 ribs and costal cartilages, sternum and associated muscles. The external, internal, innermost intercostal muscles, intercostal vessels and nerves lie in…

Embryology/Development
The mammary glands develop from ectodermal ridges that form on the ventral surface of the embryo. They extend laterally from forelimb to hindlimb and constitute the milk line. These…

Congenital absence of the sternocostal head of the pectoralis major muscle and its associated abnormalities has been described earlier in this chapter. In 5% of cadavers, a sternalis muscle can be found lying longitudinally between…

The important muscles in the region of the breast are the pectoralis major and minor, serratus anterior, and latissimus dorsi muscles, as well as the aponeurosis of the external oblique and rectus abdominis…

Puberty in girls begins at the age of 10 to 12 years as a result of the influence of hypothalamic gonadotropin-releasing hormones secreted into the hypothalamic–pituitary portal venous system. The basophilic cells…