breast anatomy board Flashcards
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.
Is amastia more commonly unilateral or bilateral?
unilateral
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?
axilla
Where is the most common site of a supernumerary nipple?
inframammary area
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.
The breast overlies which ribs?
Second to sixth.
What is the most common bacteria cultured from breast tissue?
Staphylococcus epidermidis.
Which vessel provides the dominant blood supply to the breast?
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
Axillary nodes are noted as level I, level II, or level III. What anatomic structure determines their “level”?
Pectoralis minor muscle
Where are level I axillary lymph nodes located?
Lateral/below the lower border of pectoralis minor
Where are level II axillary lymph nodes located?
Behind pectoralis minor
Where are level III axillary lymph nodes located?
Medial/above the upper border of pectoralis minor
What is the primary innervation to the nipple–areola complex?
Lateral branch of the fourth intercostal nerve