Breast Anatomy/Embryology

    What is the smallest functional unit of the breast?

Acini cell.

image    When do the mammary ridges develop in an embryo?

Fifth or sixth week of gestation.

image    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).

image    What is the result of incomplete involution of the mammary ridge?

Accessory breast tissue and supernumerary nipples.

image    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.

image    What is polymastia?

Accessory breast tissue, usually found in axilla.

image    What is polythelia?

Accessory nipples that can develop anywhere along the milk line.

image    Which is more common polymastia or polythelia?


image    What is amazia?

Nipple development without breast tissue development.

image    What is athelia?

Breast development without nipple development.

image    Is amastia more commonly unilateral or bilateral?


image    What is the cause of unilateral amastia?

Arrested mammary ridge development during the sixth week of fetal development.

image    Where is the most common site of aberrant breast tissue?


image    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.

image    Where is the most common site of a supernumerary nipple?

Inframammary area.

image    The breast overlies which ribs?

Second to sixth.

image    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.

image    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.

image    Which quadrant of the breast contains the most glandular tissue?

Upper outer quadrant.

image    What is the most common bacteria cultured from breast tissue?

Staphylococcus epidermidis.

image    Which vessel provides the dominant blood supply to the breast?

Internal mammary artery.

image    The internal mammary artery is a branch of which artery?

Subclavian artery (left)/brachiocephalic artery (right).

image    Usually, what vessel is the largest artery entering the pectoralis major muscle and overlying breast parenchyma?

The second intercostal internal mammary perforator.

image    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.

image    When dissecting the axilla, if you clip the intercostobrachial nerve, where will you lose sensation?

Upper medial aspect of arm and axilla.

image    The intercostobrachial nerve is a branch of what nerve?

Lateral branch of the second intercostal nerve.

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Aug 28, 2016 | Posted by in Reconstructive surgery | Comments Off on Breast Anatomy/Embryology
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