The document discusses the anatomy of the breast. It covers topics such as location and extent of the breast, layers and structures within the breast like skin, parenchyma, ducts and lobes. It also discusses blood supply, lymphatic drainage including lymph node stations, nerve supply and radiological anatomy of the breast.

1. Anatomy of Breast
Dr. Animesh Agrawal
Dr Ram Manohar Lohia Institute of Medical Sciences, Lucknow

2. Topics covered
• Anatomy
• Radiological anatomy
• Radiotherapy planning associated
radiological anatomy

3. • Modified sweat gland / apocrine gland /
Mammary gland
• Present in both sexes.
• Rudimentary in male, well developed in
female after puberty.

4. - Situated within the superficial pectoral fascia.
- The superficial fascia splits to enclose the breast to
form the anterior and posterior lamellae.
• Extent:
• Vertically: 2nd to 6th ribs (from the clavicle above to
the 7th/8th rib below
• Horizontally: Midline/lateral border of sternum to
mid-axillary line.
Location and Extent

5. 2nd rib
Pectoralis major
Skin
Fat6th rib

6. • The floor is formed by the deep pectoral fascia.
• This overlies pectoralis major and serratus anterior
superiorly and external oblique and its aponeurosis
inferiorly.
Floor
Pectoralis
major
Serratus
anterior
External
oblique

7. Breast in section
Pectoralis minor
Pectoralis major
Pectoral fascia
Suspensory ligament
Submammary space
Deep fascia
Superficial fascia
Adipose tissue
Rib
Secretory lobule
Non lactating
breast
Breast during
lactation

8. Muscles Anatomical significance Clinical significance
Pectoralis
major
1. Major muscle mass posterior to
breast
2. Lymphatics from breast pierce
and circumvent it.
1. Excised in radical
mastectomy
2. Anterior fascia is
removed in MRM.
Pectoralis
minor
1. Superior portion crosses anterior
to axillary sheath, dividing the axilla
into low, mid and high regions.
2. Interpectoral nodes lie
immediately anterior.
1. Landmark for Axillary
nodal levels.
2. Excised in modified
(Patey’s) mastectomy.
Serratus
anterior
1. Medial wall of axilla
2. Major muscle mass deep to lateral
one-third of breast
1. Responsible for winging
of scapula in long thoracic
nerve injury
Latissimus
dorsi
1. Post wall of axilla
2. Fascia continuous with axillary
fascia
1. Anterior border is lateral
limit of dissection
2. Used as myocutaneous
flap for breast
reconstruction.
* Other muscles like subclavius, rectus abdominis and external oblique may
come into relation and are exposed during mastectomy.

9. Naming the quadrants for the
purpose of describing a lump
 Upper Medial
 Upper lateral
 Lower medial
 Lower lateral
 Central

11. • Skin:
• Nipple
• Areola
• Parenchyma (2,3,5,6)
• Stroma (1,4)

12. Skin
Tubercle of Montgomery
Nipple
Areola

13. • The nipple is composed mostly of collagenous dense
connective tissue and contains numerous elastic fibres
which wrinkle the overlying skin.
• Usually lies above the inframammary crease, level with
the 4th rib (just lateral to the midclavicular line).
• The average nipple to sternal notch measurement in a
youthful, well-developed breast is 21-22 cm.
• An equilateral triangle formed between the nipples and
sternal notch measures an average of 21 cm per side.
Maxwell GP, Gabriel A. Breast Reconstruction. Aesthetic Plastic Surgery. (2009)
The Nipple

14. • Lobes:
- 15 – 20 in number
- Composed of glandular structures called
lobules which empty via ductules into
lactiferous ducts.
• Lactiferous ducts:
- Draining each lobe of the breast pass
through the nipple and open onto its tip as
15–20 orifices.
- Contains ampulla near its end
(Reservoir of milk or abnormal discharge)
Lobules
Ductules
Lactiferous duct
Lactiferous sinus
Nipple

15. lobe
Lactiferous duct
Lactiferous sinus

16. • Suspensory Ligament of Cooper
• Anchored to the pectoralis fascia
by the suspensory ligaments that
were first described by Astley
Cooper in 1840.
• Run throughout the breast tissue
parenchyma from the deep fascia
beneath the breast and attach to
the dermis of the skin
• Being somewhat lax, allow for the
natural motion of the breast.
• Relax with age and time,
eventually resulting in breast
ptosis.

17. Arterial Supply, Venous drainage,
Nerve supply

18. • Axillary artery
• Superior thoracic
• Thoracoacromial artery
• Lateral thoracic artery
• Subscapular artery.
• Internal thoracic:
• Perforating branches to the
anteromedial breast.
• The second to fourth anterior
intercostal arteries.
• The second perforating artery
is usually the largest; supplies
the upper region of the breast,
the nipple, areola and
adjacent breast.
Posterior surface is relatively avascular.
Blood Supply

19. Internal thoracic
artery
Axillary artery
Lateral thoracic
artery
Superior thoracic artery
Acromiothoracic
artery
Posterior intercostal
arteries

20. o Veins follow the arteries.
o First converge around the nipple to form an anastomotic
venous circle & then form 2 sets of veins.
• Superficial veins: drain into Internal thoracic vein &
superficial veins of the lower part of the neck
• Deep veins: drain into Internal thoracic, Axillary &
Posterior intercostal veins.
o Intercostal veins communicate with the vertebral veins.
This route is responsible for metastasis of CA breast to
vertebral bodies, sacrum and pelvic bones.

21. Internal Jugular vein
Subclavian vein
Celiac vein
Axillary vein
Lateral thoracic vein
Branches draining
into lateral thoracic vein
Internal Thoracic vein
along with perforators

22. Internal thoracic vein
Axillary vein
Anastomotic
venous circle

23. • 4th to 6th intercostal nerves by their Anterior & Lateral
cutaneous branches
• The nipple is supplied from the anterior branch of the
lateral cutaneous branch of T4
• Forms an extensive plexus within the nipple; its sensory fibres
terminate close to the epithelium as free endings, Meissner
corpuscles and Merkel disc endings. These are essential in
signaling suckling to the central nervous system.
• Secretory activities of the gland are largely controlled by
ovarian and hypophyseal hormones rather than by
efferent motor fibers.
• The areola has fewer sensory endings.

24. Long thoracic nerve
Posterior branches
lateral abdominal
cutaneous nerves
Anterior branches
lateral abdominal
cutaneous nerves
lateral mammary branch of
lateral pectoral cutaneous
branch of intercostal nerve
T4Intercostobrachial
nerves

25. Lymphatic Drainage

26. Introduction
• The breast is originally an ectodermal tissue, thus its
lymphatic drainage is mostly parallel to the lymph flow of
the overlying skin.
• The lymphatic flow of the breast is of great clinical
significance because metastatic dissemination occurs
principally by the lymphatic routes.

27. • Axillary (85%)
• Anterior
• Posterior
• Central
• Lateral
• Apical
• Interpectoral
• Internal mammary / Parasternal (10%)
• Others (5%)
• Supraclavicular
• Cephalic / Deltopectoral
• Posterior intercostal
• Subdiaphragmatic
• Subperitoneal
Lymph Node Stations

28. The axillary lymph nodes
• These are some 20–40 in number, grouped as
• Only the apical group is terminal.
- Anterior (4-5) Lying deep to pectoralis major along the lower border
of pectoralis minor.
- Posterior (6-7) along the subscapular vessels
- Lateral (4-6) along the axillary vein
- Central (3-4) In the axillary fat
- Apical (6-12) Through which all the other axillary nodes drain, at the
apex of the axilla above pectoralis minor and along the
medial side of the axillary vein

29. Lateral
Central
Posterior
Apical
Anterior
Interpectoral
Internal mammary
• A few efferents from apical nodes usually reach the inferior deep
cervical nodes (supraclavicular nodes).

30. Other lymph nodes
• Internal mammary or parasternal nodes: They are variable in
number and lie along the internal mammary vessels deep to
the plane of the costal cartilages.
• Most are near the bifurcation of the intercostal and internal
mammary veins.
• Efferents drain into the jugular veins.
• Inter pectoral nodes (rotter’s nodes): A few nodes lying
between the pectoralis major and minor muscles.
• Supraclavicular and other nodes: Some lymph from the
breast also reaches the supraclavicular nodes, deltopectoral
nodes, posterior intercostal nodes, subdiaphragmatic and
sub peritoneal plexuses.

31. Quadrant wise drainage
Drainage from the 5 “quadrants” towards the axilla and
internal mammary chain
Palpable + Nonpalpable lesions
Axilla (%) IMC (%)
UOQ 95.8 10.4
UIQ 93.1 32.4
LOQ 97.7 29.5
LIQ 88.0 52.7
C 100 23.7
UOQ: Upper outer quadrant. UIQ: Upper inner quadrant. LOQ: Lower outer quadrant.
LIQ: Lower inner quadrant. C: Centre
Susanne H. Estourgie et al. Ann Surg. 2004

32. • These are defined according to the surgeon’s
approach to the axillary nodes during dissection.
• Anatomical landmark used: Pectoralis minor
• Levels:
• Clinical N Staging of CA breast is done based on
these levels.
Axillary lymph nodes levels (Berg’s levels)
Level 1 Lateral to lateral border of pectoralis minor (anterior, posterior
& lateral group).
Level 2 Central axillary nodes located under pectoralis minor muscle
Level 3 Apical & infraclavicular nodes medial to pectoralis minor
muscle. It is difficult to visualize & remove unless pectoralis
muscles are sacrificed or divided.

33. Berg’s axillary
lymph node levels

34. Fig: Eventual drainage pathways of thoracic lymphatics
• Lymphatics from the left breast terminate in the thoracic
duct and subsequently the left subclavian vein. On the
right, they ultimately drain into the right subclavian vein
near its junction with the internal jugular vein.

35. • Superficial lymphatics  skin over breast except nipple &
areola
• Deep lymphatics  parenchyma as well as nipple & areola
• Subareolar plexus of Sappey is a network of lymphatics in
the areola of the nipple.
• Takes its name from Marie Philibert Constant Sappey, a French
anatomist who published his comprehensive atlas in 1874.
Lymphatic vessels
Subareolar
plexus of
Sappey
• Is a good site for injecting dye during a
sentinel lymph node biopsy.

37. Sentinel Lymph Node
• Sentinel lymph node (SLN):
• SLN biopsy was first clinically used for penile
carcinomas[2]
. Its utility in CA breast was explored in
a series of studies in the 1970s*.
• The first node in a regional lymphatic basin that
receives lymph flow from the primary tumor.
• The most lateral of the anterior group of lymph
nodes (level I) is the usual site of SLN in CA breast.
• SLN biopsy is indicated in patients with clinically node
negative disease.
* Pieter J Tanis. Breast Cancer Research. 2001

38. SLN Biopsy
• Localize tumor
• Dermal injection (raise a wheal) of radiocolloid into skin
overlying tumor in 5 locations
• 0.5 mCi Tc sulphur colloid in 0.5cc. After ~1 hour, take
patient to the OR.
• 5 cc of dye is injected, typically isosulfan blue, followed by
massaging for 5 minutes. Methylene blue can also be used.
• Subareolar injection (into Sappey’s plexus) is the best.
• The combination of radioisotope and dye provides the most
accurate means of localizing the sentinel node.[12]

40. Radiological anatomy
1. CT anatomy and Radiotherapy planning
associated radiological anatomy

41. Left Serratus
anterior

42. • CECT thorax showing
a left pectoralis major
hematoma.
(On the opposite side
the muscle is normal.)
• The pectoralis minor
can be seen
underneath.
• The Latissimus dorsi
is seen laterally.

47. Ascending aorta
Descending aorta
Pulmonary artery
Lung

49. A left level I Axillary Node

50. Advanced cancer of the right breast invading the chest wall

51. Breast & Chest wall Contours: Anatomical Boundaries
[13]
Cranial Caudal Ant Posterior Lateral Medial
Breast Clinical
reference +
2nd rib
insertion
Clinical
reference +
Loss of CT
apparent
breast
Skin Excludes
Pectoralis
chest wall
muscles, &
ribs
Clinical
reference +
mid axillary
line typically,
excludes Lat.
dorsi
Sternal-rib
junction
Breast +
chest
wall
Same Same Same Includes
pectoralis,
chest wall,
ribs
Same Same
Chest
wall
Caudal
border of
the clavicle
head
Clinical
reference +
loss of CT
apparent
breast
Skin Rib-pleural
interface
(includes
pectoralis,
chestwall
muscles, ribs)
Clinical
reference/mi
d axillary line
typically,
excludes Lat.
dorsi
Sternal rib
junction

58. Cranial Caudal Anterior Posterior Lateral Medial
Supra
Clavivular
Caudal to
cricoid
Junction of
brachio
cephalic veins
/ caudal edge
clavicle head
Sterno-
mastoid
(SCM)
Ant
aspect of
Scalene
Cranial: lat
edge SCM
Caudal:
Junction 1st
rib-clavicle
Exclude
thyroid
and
trachea
Axillary
Level I
Axillary
vessels cross
lat edge of
pect minor
Pectoralis
major insert.
Into ribs
Plane
defined by
ant surface
of pec
major + Lat
dorsi
Ant
surface of
sub-
scapularis
Medial border
of Lat dorsi
Lateral
border
Pec minor
Axillary
Level II
Axilarry
vessels cross
medial edge
of pect minor
Axillary
vessels cross
lat edge of
Pec minor
Ant surface
Pec minor
Ribs and
inter-
costal
muscles
Lat border
Pec minor
Medial
border
Pec minor
Axillary
Level III
Pect minor
insert. on
cricoid
Axillary
vessels cross
medial edge
Pec minor
Post
surface
Pect major
Ribs and
inter-
costals
Medial border
Pect minor
Thoracic
inlet
Internal
mammary
Superior aspect
medial 1st rib
Cranial aspect
of 4th rib
- - - -
Regional Node Contours: Anatomical Boundaries
[13]

66. Radiological anatomy
2. Mammography

67. BIRADS
• American College of Radiology (ACR) has
devised the Breast Imaging Reporting and Data
System (BI-RADS), a standardized method for
describing the morphology of breast lesions.
• These are described for imaging of the breast.
(Mammography, USG breast and MRI)

68. Category Description Likelihood of
Malignancy
Next step
0 Incomplete; need
further evaluation
Unknown Further imaging/
comparison
1 Negative No evidence of
malignancy
Routine screening
2 Benign No evidence of
malignancy
Routine screening
3 Probably benign Less than 2% F/U imaging at 6 and at
12 months
4 Suspicious for
malignancy
2-95% Tissue diagnosis
5 Highly suggestive
of malignancy
>95% Tissue diagnosis
6 Known malignancy 100% Treatment

69. • For mammography and Ultrasound of the breast,
BIRADS category 4 is divided into 3 sub groups:
Category Description Likelihood of
Malignancy
Next step
4 Suspicious
4A: Low
4B: Moderate
4C: High
2-95%
2-10%
10-50%
50-95%
Tissue diagnosis

70. Mammography
• The following are reported:
1. Categories of breast density
2. Mass descriptors in mammography
a) Shape
b) Margin
c) Density
3. Calcifications

71. Positioning for Mammography
A. MLO view. The MLO view is obtained with the tube angled at 45° to
the horizontal, with compression applied obliquely across the chest
wall, perpendicular to the long axis of the pectoralis major muscle.
B. CC view. Positioning is achieved by pulling the breast up and
forward, away from the chest wall, with compression applied from
above.

72. 2 Views
Craniocaudal viewMediolateral Oblique view

73. a to d: ACR categories
of breast parenchymal
density.
a. Breast tissue almost
entirely fatty (little
glandular tissue)
b. Scattered fibroglandular
tissue
c. Heterogeneously dense
parenchyma, which may
obscure small masses
d. The breasts are extremely
dense, which lowers the
sensitivity.
a b
c d

74. A-D: ACR BI-RADS
descriptors for mass
shape on
mammography.
A. Round
B. Oval
C. Lobulated
D. Irregular
A B
DC

75. ACR BI-RADS
descriptors for
mass margins on
mammography.
A. Circumscribed
(sharply defined)
B. Obscured
C. Indistinct
D. Spiculated
A
C
B
D

76. • ACR BI-RADS descriptors for mass density (as compared
to the fibroglandular parenchyma) on mammography.
A. High density mass
B. Isodense mass
C. Low density mass. MLO view showing a large heterogeneous mass
in the breast (arrows) containing areas of fat density within,
consistent with the diagnosis of hamartoma
A B C

77. Typically benign calcifications.
A. Lucent-centered calcifications consistent with skin
calcifications
B. Vascular calcification
C. Popcorn calcifications within involuted fibroadenoma
D. Rod like ductal calcifications
E. Coarse dystrophic calcifications seen in a postoperative,
irradiated breast
A
B C D E

78. Calcifications of
intermediate
concern
A. Amorphous
calcifications
B. Coarse
heterogeneous
calcifications
Calcifications having
high probability of
malignancy.
A. Pleomorphic
calcifications
B. Fine heterogeneous
calcifications
A B
A B

79. Descriptors for distribution of calcifications.
A. Clustered (>5/cc)
B. Ductal (within a duct)
C. Segmental (within a single lobe)
D. Scattered/Diffuse (more than 1 lobe)
A B C D

80. Mammographic Features of
Breast Cancer:
• Asymmetry
• Architectural distortion
• Heterogenous mass
• Irregular margins
• Areas of skin thickening
• Microcalcifications

81. Some examples

82. • Post op screening mammogram
shows the surgical scar. The
ring like opacity is likely a
suture.
Mammography shows nipple
and areolar thickening in right
breast with a subareolar mass:
Paget’s disease

83. Ductogram
• Performed by injecting contrast
material into an orifice of a
lactiferous duct at the nipple, a
ductogram demonstrates the
complex ramifications of a single
mammary ductal system.
• The primary indication is to
evaluate a single duct which has
a discharge.
• Seldom done now due to advent
of USG and MRI.

84. Ductogram

85. Radiological anatomy
3. Ultrasound of Breast

86. Ultrasound of breast:
• A valuable adjunct to mammography for the diagnosis of
breast diseases.
o Particularly useful in young women with dense breasts
in whom mammograms are difficult to interpret.
o Distinguishes cysts from solid lesions.
o Can be used to localize impalpable breast lumps.
o Can also be used for a guided FNAC/Biopsy.
o Assessment of mammographic abnormality
o Lactating and pregnant women
o Women < 30 years of age

87. • Normal tissue planes:
• skin 1-3mm
• subcutaneous fat
• Normal ducts
• Solid/cystic
• Size/dimensions
Ultrasound

88. Benign lesions
• Smooth & regular
• Thin ‘pseudocapsule’
• Uniform internal echoes
• Cystic
• Tissue planes preserved
Ultrasound

89. Suspicious
• Irregular margins (A)
• Spiculation
• Taller than wide (B)
(anti-parallel)
• shadowing
• Posterior acoustic shadowing
• disruption of tissue planes
A
B
Ultrasound

90. Posterior acoustic enhancement (A) vs Posterior acoustic shadowing (B)
A B
• Disadvantages:
o Operator dependent
o Time consuming

91. Radiological anatomy
3. MRI

92. MRI of Breast
• A recent meta-analysis of 44 studies has estimated the
sensitivity and specificity of MRI for the diagnosis of
breast cancer as 90% & 72%.[10]
• It is particularly useful in
• Dense breasts
• Palpable abnormality with normal mammogram
• Augmented breasts
• To stage a tumor (eg chest wall invasion)

93. A. Mammogram shows a plane of
cleavage between the large
stellate irregular tumor and the
pectoralis muscle.
B. MRI shows that the tumor is
attached to the pectoral fascia,
and the images show some
underlying muscle and fascial
enhancement.
A. Only 1 lesion - a focal,
spiculated, small nodule was
found in mammography.
B. MRI shows 2 strongly
enhancing irregular nodules,
both of which were consistent
with malignancy.

94. Mass shape
characteristics:
A. Round
B. Oval
C. Irregular
D. Spiculated
A B
C D

95. Descriptors for internal enhancement characteristics
A. Homogeneous
B. Heterogeneous
C. Rim enhancement
A B C
• Non-mass like enhancement.
Enhancement occurs in an
area of the fibroglandular
tissue that otherwise appears
normal in precontrast images.

96. A. Mammogram shows a high density, irregular, spiculated mass
B. Ultrasound shows a hypoechoic, irregular, spiculated mass with
distal acoustic shadowing
C. Contrast enhanced T1-weighted MRI shows a spiculated, intensely
enhancing mass

97. Newer techniques
• Molecular Breast Imaging
• Digital Breast Tomosynthesis
• Electrical impedance imaging
Experimental
• Optical imaging tests

98. Molecular Breast Imaging
• New Technique using targeted molecules (eg. FES for the
estrogen receptor).
• Has been shown to be a good complementary technique to
conventional mammography, especially for women with a
dense breast.[4, 5]
• Especially useful for imaging patients who cannot have an
MRI.[6]
• More cost effective and less time consuming than MRI.[6,7]

101. Digital Breast Tomosynthesis
• Developed to improve detection and characterization of
breast lesions especially in women with dense breasts
• In this technique, multiple projection images are
reconstructed allowing visual review of thin breast
sections.
• Potential to unmask cancers obscured by normal tissue
located above and below the lesion, but no randomized
evidence of advantage over mammograms yet.[8]

102. Conventional mediolateral oblique mammography view (A) of a
patient with invasive ductal cancer. Vaguely apparent on the
conventional mammogram, the lesion is much better visualized on
the 1 mm thick tomosynthesis image (B).
A B
Digital Breast Tomosynthesis

103. Thank You