What is the smallest functional unit of the breast?
When do the mammary ridges develop in an embryo?
Fifth or sixth week of gestation.
What is the path of the mammary ridge along the ventral aspect of an embryo?
Base of the forelimb (future axilla) to the base of the hindlimb (inguinal area).
What is the result of incomplete involution of the mammary ridge?
Accessory breast tissue and supernumerary nipples.
What is the difference between accessory and ectopic breast tissue?
Accessory breast tissue occurs in the mammary line from axilla to groin, whereas ectopic breast tissue can occur anywhere outside the mammary line.
What is polymastia?
Accessory breast tissue, usually found in axilla.
What is polythelia?
Accessory nipples that can develop anywhere along the milk line.
Which is more common polymastia or polythelia?
Nipple development without breast tissue development.
What is athelia?
Breast development without nipple development.
Is amastia more commonly unilateral or bilateral?
What is the cause of unilateral amastia?
Arrested mammary ridge development during the sixth week of fetal development.
Where is the most common site of aberrant breast tissue?
Which is more concerning: unilateral or bilateral inverted nipples?
Unilateral; bilateral is usually an associated benign congenital condition. Unilateral is more often associated with pathologic findings such as cancer.
Where is the most common site of a supernumerary nipple?
The breast overlies which ribs?
Second to sixth.
Each cluster of alveoli leads to a milk duct that empties into a lactiferous sinus. Each lactiferous sinus drains one lobe of the breast. How many lobes are in the breast?
15 to 25 lobes per breast.
What is the difference between a breast lobule and a breast lobe?
Lobes consist of multiple lobules and their respective interlobular ducts. Lobules are composed of glandular tissue containing acini cells that produce milk.
Which quadrant of the breast contains the most glandular tissue?
Upper outer quadrant.
What is the most common bacteria cultured from breast tissue?
Internal mammary artery.
The internal mammary artery is a branch of which artery?
Subclavian artery (left)/brachiocephalic artery (right).
Usually, what vessel is the largest artery entering the pectoralis major muscle and overlying breast parenchyma?
The second intercostal internal mammary perforator.
Name three branches of the axillary artery (from medial to lateral) that serve as blood supply to the breast.
Thoracoacromial, lateral thoracic, and thoracodorsal arteries.
When dissecting the axilla, if you clip the intercostobrachial nerve, where will you lose sensation?
Upper medial aspect of arm and axilla.
The intercostobrachial nerve is a branch of what nerve?
Lateral branch of the second intercostal nerve.