THE BREAST
I. Introduction/General Information
A. Embryologically: belong to integument
B. Functionally: part of reproductive
system
1. Respond to sexual stimulation
2. Feed babies
Breast, continued …
C. Modified apocrine sweat glands
- apex of cell becomes part of secretion
and breaks off
D. Present in males and females
II. Anatomy
A. Position and Attachment
1.
2.
3.
4.
5.
Lateral aspect of pectoral region
Located between ribs 3 and 6/7
Extend form sternum to axilla
Surrounded by superficial fascia
Rest on deep fascia
Breast Anatomy
Position & attachment, continued ….
6. Fixed to skin & underlying
fascia by fibrous C.T. bands
a. Cooper’s (Suspensory)
Ligaments
b. Ligaments may retract when
breast tumors are present
Cooper’s Suspensory Ligaments
Position & attachment, continued …
6. Left breast is usually slightly larger
7. Base is circular, either flattened or
concave
8. Separated from pectoralis major
muscle by fascia, retromammary
space
Retromammary Space
Retromammary
Space
Anatomy, continued …
B. Structure
1. Outer surface convex, skin covered
2. Nipple:
a. At fourth intercostal space
b. Small conical/cylindrical
prominence below center
Nipple location
4th
intercostal
space
Structure, continued …
c. Surrounded by areola: pigmented
ring of skin
d. Thin skinned region lacking hair,
sweat glands
e. Contains areolar glands
Structure, continued …
3. Areola: contains dark pigment that
intensifies with pregnancy
a. Circular and radial smooth muscle
fibers
b. Cause nipple erection
Areola
Structure, continued …
4. Each breast consists of ~ 20 lobes
of secretory tissue
a. Each lobe has one lactiferous duct
b. Lobes (and ducts) arranged radially
c. Embedded in connective tissue &
adipose of superficial fascia
d. Lobes composed of lobules
e. Lobules comprise alveoli
Lobes and Lobules
Structure, continued …
5. Excretory (lactiferous) ducts converge
toward areola
a. Form ampullae (collection sites of
lactiferous sinuses)
b. Ducts become contracted at base of
nipple
Excretory (lactiferous) ducts
Structure, continued …
6. Secretory epithelium
a. Changes with hormonal signals
b. Onset of menstruation
c. Pregnancy (glands begin to
enlarge at 2nd month)
d. After birth, 1st secretion is
colostrom (contain antibodies)
Structure, continued …
7. “Tail of Spence” = axillary tail
a. prolongation of upper, outer
quadrant in axillary direction
b. Passes under axillary fascia
c. May be mistaken for axillary lymph
nodes
“Tail of Spence”
Axillary Tail
Structure, continued …
8. Fatty Tissue: surrounds surface, fills
spaces between lobes
a. Determines form & size of breast
b. No fatty deposit under nipple &
areola
Breast: Fatty Tissue
Structure, continued …
C. Vessels & nerves
1. Arteries: derived from thoracic
branches of three pairs of arteries
a. Axillary arteries
1) continuous with subclavian a.
2) gives rise to external mammary
( = lateral thoracic) artery
Vessels & Nerves, continued …
b. Internal mammary (thoracic) arteries
1) first descending branch of
subclavian artery
2) supply intercostal spaces & breast
3) used for coronary bypass surgery
c. Intercostal arteries:
1) numerous branches from internal
& external mammary arteries
2) supply intercostal spaces & breast
Arterial Supply to the Breast
Subclavian a.
Axillary a.
External
mammary
(thoracic) a.
Internal
mammary
(thoracic) a.
Vessels & Nerves, continued …
2. Veins:
a. form a ring around the base of the
nipple (“circulus venosus”)
b. Large veins pass from circulus
venosus to circumference of
mammary gland, then to
c. External mammary v to axillary v
or
d. Internal mammary v to subclavian v
Veins draining the Breast
Subclavian vein
External
mammary vein
Breast Anatomy, con’t…
3. Innervation: derived from:
a. anterior & lateral cutaneous
nerves of thorax
b. spinal segments T3 – T6
Structure, continued …
4. Lymphatics: clinically significant!
a. Glandular lymphatics drain into
anterior axillary (pectoral) nodes 
central axillary nodes 
apical nodes 
deep cervical nodes 
subclavicular (subclavian) nodes
b. Medial quadrants drain into
parasternal nodes
Lymph Nodes of the Breast
Subclavian
nodes
Axillary
nodes
Lateral
pectoral
nodes
Parasternal
nodes
Lymphatics, continued …
c. Superficial regions of skin, areola,
nipples:
-form large channels & drain into
pectoral nodes
d. NOTE: axillary nodes also drain lymph
from arm
Lymph Nodes and Lymph Drainage
Axillary
Nodes
Routes of Metastasis

From medial lymphatics to parasternal nodes


Across the sternum in lymphatics to
opposite side via cross-mammary pathways


Then to mediastinal nodes
Then to contralateral breast
From subdiaphragmatic lymphatics to nodes in
abdomen

Then to liver, ovaries, peritoneum
Major Routes of Metastasis
Channels to Contralateral Breast
Axillary Lymph Channels
Subdiaphragmatic Lymph Channels
Structure, continued …
D. Anomalies
1. Inverted nipple: congenital or due
to cancer
2. Ectopic nipple:
a. “polythelia” or “hyperthelia”
b. additional nipples along milk line
3. Amastia
4. Micromastia
Anomalies, continued …
5. Macromastia
6. Gynecomastia
a. breast development of male in
areolar region
b. noted in males who smoke
marijuana at puberty
III. Diseases of the Breast
A. Most are readily detectable
B. Etiology unknown, influencing factors
1. Sex
2. Heredity
Diseases of the breast, continued …
3. Endocrine influence
a. Menstruation – tenderness from
fluid engorgement
b. Post-menopause
1) decrease of fibro-cystic disease
2) increase in cancer
c. Pregnancy
Diseases of the Breast, continued …
C. General symptoms & signs
1. Nipple discharge
a. always significant if not pregnant.
b. May be due to benign pituitary tumor.
2. Local pain, tenderness
3. Duration of lesion
4. Size, rate of growth
Symptoms & Signs, continued …
5. Retraction sign: “dimpling” involving
skin, nipple or areola
6. Mobility of mass
a. Benign = movable
1) not attached
2) not invasive
b. Malignant = attached
1)May grow into bone
Symptoms & Signs, continued …
7. Consistency of mass
a. Cysts = fluctuant; compressible
b. Fibroadenoma = rubbery
c. Carcinoma = firm, hard (like gravel)
8. Axillary area lymph node enlargement
D. Benign breast conditions
1. Infection = usually during or after
lactation
a. Recurrent, subareolar abscess
b. TB of the breast
2. Trauma = contusion
3. Hypertrophy = seen in either sex at
adolescence
a. Gynecomastia = in males
Hypertrophy, continued …
b.
Other causes
1) testicular or pituitary tumor
2) cirrhosis
3) hypogonadism = not enough
testosterone
4) estrogen administration for
prostate cancer
Benign Conditions, continued
4.
Tumors & cysts
a. Fibroadenoma =
most common
benign breast
tumor
Tumors and Cysts, con’t…
b. Breast Cyst
1. Benign
2. May be
aspirated if
large
Benign conditions, continued …
c. Fibrocystic breast
changes
1) 20%+ of premenopausal
women
2) discomfort, cysts
3) treatment rarely required
4) More likely to not detect a
developing cancer
Tumors & cysts, continued ….
d. Intraductal papilloma
- may produce
“chocolate” or
bloody discharge from
nipple
e. Lipoma: common
- fatty tumors
E. Carcinoma of the breast
1. Most common malignant tumor among
women
2. 1/8 of women will develop breast cancer
a. 1/6 in Orange County
b. 1/5 in San Francisco
3. Generally no discomfort
Progression to Breast Cancer
Carcinoma of breast, continued …
4. Physical signs:
a.
b.
c.
d.
Slowly growing, painless mass
May demonstrate retracted nipple
May be bleeding from nipple
May be distorted areola, or breast
contour
e. Skin dimpling in more advanced
stages with retraction of Cooper’s
ligaments
Physical signs, continued …
f. Attachment of mass
g. Edema of skin
1)with “orange skin” appearance
(peau d’orange)
2) due to blocked lymphatics
h. Enlarged axillary or deep cervical
lymph nodes
Breast Cancer, con’t…
5. Common sites for metastasis
a. Lungs & pleura
b. Skeleton system (skull, vertebral column,
pelvis)
c. Liver
6. Atypical carcinomas
a. Inflammatory carcinoma (hormonal,
chemotherapy)
b. Paget’s disease of the breast