The Human Breast and Pectoral Muscles

Vocabulary flashcards covering the main terms and their definitions from the lecture notes on the human breast and the pectoral muscles.

Human Breast

present in both males and females with development differing.

Mammary Glands

Glands present in both sexes; develop in females around puberty and remain undeveloped in males; main function is to secrete milk to nourish infants.

Lactiferous Ducts

Location where mammary gland drains; milk exits through multiple tiny holes in the nipple; ducts drain toward the nipple and areola.

Areola

The darker area surrounding the nipple; darkens during pregnancy to help newborns locate the breast due to limited vision.

Myoepithelial Cells

Line mammary glands and contract to eject milk through the lactiferous ducts.

Myoepithelial Etymology

'Myo' = muscle/contractile; 'Epithelial' = lining cells;

Breast Connective Tissue

collagen provides strength; elastin provides elasticity

form Cooper’s Ligaments

Cooper’s Ligaments

Connective tissue strands that anchor the breast to the chest wall

Adipose Tissue

Soft, fatty tissue of the breast; contributes to breast shape and structure; supports mammary glands with connective tissue.

Pectoral Region

Anterior chest wall; contains four muscles essential for shoulder and chest movement.

Pectoralis Major

Most superficial pectoral muscle with two heads

Functions to adduct and medially rotate humerus

Clavicular Head of Pectoralis Major

Originates from the clavicle and inserts on the humerus (lateral lip of the bicipital groove)

Function includes flexion of the arm at the shoulder.

Sternocostal Head of Pectoralis Major

Originates from the sternum, superior six costal cartilages, and external oblique aponeurosis; inserts on the humerus (lateral lip of bicipital groove)

Function is to extend the arm at the shoulder; also a prime mover of pushups.

Pectoralis Minor

Deep to the pectoralis major; originates from ribs 3–5 and inserts on the coracoid process of the scapula

Function is to pull the scapula in toward the thoracic wall and stabilize it.

Serratus Anterior

Muscle that anchors the scapula to the ribcage and pulls it forward; originates from ribs 1-8 or 1-9; inserts on costal surface of scapula’s medial border

Allows raising the arm above 90 degrees by enabling scapular rotation beyond 90 degrees of abduction.

Serratus Anterior Divisions

superior, intermediate, inferior

Subclavius

Runs horizontally underneath the clavicle; originates at the junction of rib 1 and its costal cartilage and inserts on the inferior surface of the clavicle;

Function is to anchor the clavicle, move it down and forward, and protect the brachial plexus.