Breast Anatomy/Embryology - Board Review Flashcards

1
Q

Smallest functional unit of the breast?

A

Acini cell

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2
Q

When do the mammary ridges develop in an embryo?

A

5-6 weeks

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3
Q

What is the path of the mammary ridge along the ventral aspect of an embryo?

A

Base of the forelimb (future axilla) to the base of the hindlimb (inguinal area)

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4
Q

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

A

accessory breast tissue and super numerary nipples

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5
Q

What is the difference between accessory and ectopic breast tissue?

A

Accessory breast tissue is along the mammary ridge and ectopic is elsewhere

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6
Q

What is polymastia?

A

Accessory breast tissue, usually found in axilla

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7
Q

What is polythelia?

A

Accessory nipples (along the milk line)

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8
Q

What is amazia?

A

Nipple development without breast development

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9
Q

What is athelia?

A

Breast development without nipple development

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10
Q

Is amastia more common unilateral or bilateral?

A

Unilateral

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11
Q

What is the cause of unilateral amastia?

A

Arrested mammary ridge development during the sixth week of fetal development

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12
Q

Where is the most common site of aberrant breast tissue?

A

axilla

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13
Q

Which is more concerning, unilateral or bilateral inverted nipples?

A

Unilateral may be associated with cancer; bilateral is usually associated with benign congenital conditions.

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14
Q

What is the most common site for supernumerary nipples?

A

Inframammary area

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15
Q

The breast overlies which ribs?

A

2-6

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16
Q

Each cluster of alveoli leads to a milk duct that empties into a lactiferous sinus. Each lactiferous sinus drains into one lobe of the breast.
How many lobes are in the breast?

A

15-25 lobes

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17
Q

What is the difference between a breast lobule and a breast lobe?

A

Lobes consist of multiple lobules and their respective interlobular ducts. Lobules are composed of glandular tissue containing acini cells that produce milk.

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18
Q

Which quadrant of the breast contains the most glandular tissue?

A

Upper outer

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19
Q

What is the most common bacteria cultured from breast tissue?

A

Staph epidermidis

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20
Q

Which vessel provides the dominant blood supply to the breast?

A

Internal mammary

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21
Q

The internal mammary artery is a branch of which vessel?

A

Subclavian artery (left) and brachiocephalic (right)

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22
Q

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

A

The second intercostal mammary perforator

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23
Q

Name three branches of the axillary artery (from medial to lateral) that serve as blood supply to the breast

A

Thoracoacromial, lateral thoracic, and thoracodorsal

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24
Q

During dissection of the axilla, if you cut the intercostobrachial nerve, where will you lose sensation?

A

upper medial aspect of the arm and axilla

25
The intercostobrachial nerve is a branch of which nerve?
Lateral branch of the second intercostal nerve
26
Axillary nodes are noted as level I, level II and level III. What anatomic structure determines their level?
Pectoralis minor muscle
27
Where are Level I axillary nodes located?
Lateral/below pectoralis minor muscle
28
Where are Level II axillary nodes located?
Behind pectoralis minor muscle
29
Where are Level III axillary nodes located?
Medial/Above border of pectoralis minor muscle
30
Where is a Rotter's node?
Interpectoral
31
What is the primary innervation of the NAC?
Lateral branch of the fourth intercostal nerve
32
What is the course of the lateral branch of the fourth intercostal nerve?
It pierces the deep fascia in the mid axillary line and takes an inferomedial course within the pectoral fascia. On reaching the mid clavicular line, it turns 90° and continues through the glandular tissue toward the posterior surface of the nipple.
33
What is the normal diameter of the NAC?
35-45mm
34
What is the dominant blood supply to the NAC?
perforators from the internal mammary artery
35
What is the function of the Montgomery glands?
They are sebaceous glands that produce a waxy substance to assist with lubrication and protection of the NAC
36
What ligaments provide support to the breast tissue and what do they connect?
Cooper's ligaments; between deep pectoralis fascia and the skin (dermis)
37
What are the borders of the breast?
Latissiumus dorsi (lateral), clavicle(superior), lateral sternum(medial), IMF (inferior) pectoralis major (deep)
38
What is the major component of the anterior axillary fold?
Pectoralis major muscle
39
What is the origin of the pectoralis major muscle?
Medial sternal half of the clavicle and lateral aspect of the sternum/costochondral region, from sternal notch down to the 6-7 costal cartilage
40
The insertion of the pectoralis major muscle lies between which muscles?
coracobrachialis (posterior) and deltoid (anterior)
41
Which nerve provides motor innervation to the lateral and inferior pectoralis major muscles?
Medial pectoral nerve
42
Serratus anterior origin and insertion, innervation
Origin: the costal attachments of the anterolateral aspects of the first through 8th ribs. Insertion: Deep medial surface of the scapula Innervation: Long thoracic nerve
43
What is the clinical manifestation of injury to the long thoracic nerve?
Winged scapula
44
Where is the long thoracic nerve located?
Positioned laterally, superficial to the external surface of the serratus anterior muscle in the mid axillary line
45
Which nerves supply innervation to the medial breast?
The 2nd-6th intercostal nerves
46
What is Poland Syndrome ?
Associated with congenital absence of the pectoralis major muscle, usually sternal component, and breast/areolar hypoplasia, costal cartilage and rib defects, hypoplasia of the subcutaneous tissues of the chest wall, brachysyndactyly
47
Following efferent lymphatic drainage pathway of the breast, what are the nodal basins in order?
Deep pectoral, subscapular, central axillary, apical axillary, supraclavicular nodes
48
If lymphatic drainage takes a medial pathway (vs draining into the axilla), what is the primary nodal basin?
Internal mammary/parasternal nodes
49
T/F: Axillary nodes drain the lateral breast and medial nodes drain medial breast?
FALSE. Both nodal basins receive drainage from the whole breast
50
Which hormone is principally responsible for ductal development and maintenance of the glandular elements during reproductive years?
Estrogen
51
Which hormone is principally responsible for lobular development and differentiation of the epithelial cells?
progesterone
52
Which hormone stimulates the differentiation of milk-producing components?
Prolactin
53
Which hormone, produced by the pituitary gland, causes ductal contraction with lactation?
Oxytocin
54
What tanner stage is the adult breast?
Tanner 5
55
What is the etiology of a congenital inverted nipple? What is its incidence?
Failure of the mammary pits to elevate above the skin during infancy; 2-4%
56
What are the normal measurements for a non-ptotic breast? Location of NAC SN to Nipple Nipple to IMF
Above IMF 17-21cm 7-8cm
57
What is the average diameter and projection of the nipple?
5-8mm | 5mm
58
What is the anatomic abnormality with tuberous breast deformity?
NAC hypertrophy, constricted breast/lower pole, herniation of the breast tissue into the NAC, high IMF