Anatomy of the breast for medical/dental students. This presentation also contains MCQs to test your knowledge as well as clinical scenario to apply your knowledge.

1. Anatomy of the breast
Yapa Wijeratne
Faculty of Medicine
University of Peradeniya

3.  Modified sweat gland- modified apocrine gland
 Made up of 15–20 lobules of glandular tissue
embedded in fat.
 Fat accounts for its smooth contour and most of
its bulk.
 These lobules are separated by fibrous septa
running from the subcutaneous tissues to the
fascia of the chest wall (the ligaments of
Cooper/ Astley Cooper fibers/ suspensory
ligaments)
 Between the capsule and the fascia over
pectoralis major is the loose connective tissue of
the retromammary space.

4.  Each lobule drains by its lactiferous
duct on to the nipple, which is
surrounded by the pigmented areola.
 This area is lubricated by the areolar
glands of Montgomery
◦ large,
◦ modified sebaceous glands →may form
sebaceous cysts → may infected.

5. Surface anatomy

6. Naming the quadrants for the
purpose of describing a lump
 Or
1. Upper medial
quadrant
2. Upper lateral
quadrant
3. Lower medial
quadrant
4. Lower lateral
quadrant

7. Position & extent
 2/3 rests on
pectoralis major,
 1/3 on serratus
anterior,
 while its lower
medial edge just
overlaps the upper
part of the rectus
sheath.

9. Cross section

11. Blood supply

12.  Axillary artery →
◦ Lateral thoracic (mainly)
◦ Acromiothoracic branches.
 Internal thoracic (internal mammary)
artery → perforating branches; these pierce
the 1st – 4th intercostal spaces, then traverse
pectoralis major to reach the breast along its
medial edge. The 1st & 2nd perforators are
the largest of these branches.
 Intercostal arteries → lateral perforating
branches- relatively unimportant source.

13. Venous drainage

14. Venous drainage
 Sub areolar venous plexus
 Posterior intercostal veins
communicate with internal vertebral
venous plexus veins - therefore
cancers can spread to vertebra- may
cause back pain

15. Lymphatic drainage

17.  Follows the pathway of its blood supply
 along tributaries of the
1. axillary vessels → axillary lymph
nodes;
2. internal thoracic vessels → piercing
pectoralis major → to traverse each
intercostal space → to lymph nodes
along the internal mammary chain;
these also receive lymphatics
penetrating along the lateral perforating
branches of the intercostal vessels.

18.  A subareolar plexus of lymphatics
below the nipple (the plexus of
Sappey)
 75% → axillary
 15% → internal mammary
 Upper → can go to supraclavicular
 Lower 2 quadrants can go to
subdiapragmatic or abdominal nodes

20. Dermatomal supply

21. Development and structure
 Begins to develop as early as the 4th week as
a downgrowth from a thickened mammary
ridge (milk line) of ectoderm along a line
from the axilla to the inguinal region.
 Supernumerary nipples or even glands
proper may form at lower levels on this line.
 Lobule formation occurs only in the female
breast & does so after puberty.
 Each lactiferous duct is connected to a tree-
like system of ducts and lobules, intermingled
& enclosed by connective tissue to form a
lobe of the gland.

23.  The resting (non-lactating) breast, however
consists mostly of fibrous & fatty tissue;
variations in size are due to variations in fat
content, not glandular tissue which is very
sparse.
 During pregnancy alveoli bud off from the
smaller ducts & the organ usually enlarges
significantly, & more so in preparation for
lactation.
 When lactation ceases there is involution of
secretory tissue.
 After menopause progressive atrophy of
lobes & ducts takes place.

24. The male breast
 Resembles the rudimentary female
breast
 has NO lobules or alveoli.
 The small nipple and areola lie over
the 4th intercostal space.

25. Test your knowledge

26. 1. The retromammary space is located
between which of the following
structures?
 (A) skin and the areola
 (B) pectoralis major and minor
 (C) breast and deep pectoral fascia
 (D) suspensory ligament and the skin
 (E) lactiferous sinus and the nipple

27. Answer
(C) Between the breast and deep
pectoral fascia is a loose connective
tissue plane or potential space known
as the retromammary space

28. 2.The mammary glands are modified
versions of which type of gland?
 (A) sebaceous gland
 (B) lymph gland
 (C) sweat gland
 (D) tonsillar tissue
 (E) endocrine gland

29. Answer
(C) The mammary glands are modified
sweat glands

30. 3. Which of the following does NOT
supply the breast with blood?
 (A) lateral thoracic artery
 (B) thoracoacromial artery
 (C) posterior intercostals arteries
 (D) internal thoracic artery
 (E) costoclavicular artery

31. Answer
 (E) The breast is supplied by the
1. internal thoracic,
2. lateral thoracic,
3. thoracoacromial, and posterior
4. intercostal arteries

32. 4. The high death rate associated with
breast cancer is related to which of the
following?
 (A) nerve supply
 (B) blood supply
 (C) venous drainage
 (D) poor imaging techniques
 (E) complex lymphatic drainage

33. Answer
 (E) Because the axillary lymph nodes are the
most common site of metastases from a
breast cancer, enlargement of the palpable
nodes in a woman suggests the possibility of
breast cancer and may be key to early
detection.
 However, the absence of enlarged axillary
nodes is no guarantee that metastasis from a
breast cancer has not occurred, because the
malignant cells may have passed to other
nodes, such as the infraclavicular and
supraclavicular lymph nodes

34. 5. Which statement most appropriately
describes the female breast?
1. It overlies the 3rd to 8th ribs.
2. It consists of 2–3 lobules.
3. It has suspensory ligaments, which tether
the dermis to the fascia of the chest wall.
4. The retro-mammary space lies deep to
pectoralis major.
5. The areolar glands are responsible for
lactation.

35. Answer
 c. The dermis is tethered to the breast
ducts and the deep fascia overlying
pectoralis major by fibrous strands
known as the suspensory ligaments of
Cooper. As these atrophy and weaken
with age the breast becomes more
pendulous.

36.  Explanations
 a. The base of the adult female breast consistently
overlies the 2nd to 6th ribs, from the sternal edge to the
midaxillary line. The upper outer quadrant extends
towards the axilla as the “axillary tail”.
 b. The breast consists of 15–20 lobules of glandular
tissue, all individually drained by a corresponding
lactiferous duct, which empty at the nipple via the
lactiferous sinus.
 d. The retro-mammary space is located between the
posterior capsule of the breast and the fascia over
pectoralis major. This space is commonly exploited in the
placement of implants.
 e. The areolar glands of Montgomery are modified
sebaceous glands located beneath the areola and are
responsible for lubricating the area. These glands may
enlarge or become infected, especially during
pregnancy.

37. 6. Which of these statements are true
considering the vasculature and
lymphatic drainage of the breast?
1. The main blood supply is derived from
branches of the internal mammary artery.
2. Venous drainage is predominantly to the
internal mammary vein.
3. Lymphatic drainage is divided evenly
between the axillary and internal
mammary nodes.
4. The superficial lymphatics of each breast
remain separate in healthy people.
5. All the axillary lymphatics drain through
the apical axillary nodes.

38. Answer
 e. There are five main groups of
nodes in the axilla. The anterior,
posterior, lateral and central groups
empty into the apical group. The
apical nodes drain into the subclavian
lymph trunk.

39.  Explanations
 a. The main supply is via the lateral thoracic and
thoracoacromial branches of the axillary artery. The internal
mammary (internal thoracic) artery supplies a significant
part of the medial aspect via perforating branches. The
posterior intercostal arteries also make a minor contribution.
 b. Venous drainage follows the arterial supply of the breast
and is primarily to the axillary vein.
 c. Approximately 75% of drainage is to the axillary lymph
nodes, primarily to the anterior group. The majority of the
remaining drainage, especially of the medial part, is to the
internal mammary nodes.
 d. The superficial lymphatics have connections with the
opposite breast and anterior abdominal wall. If the normal
drainage channels become obstructed by malignant
disease, metastatic spread may, therefore, occur to the
contralateral breast or axillary nodes.

40. Name the anatomical structure/s
involved
 Pt who is found to have a breast lump also
having a lump in the axilla?
 LN enlargement
 There is a dimpling of the overlying skin of
the breast
 Suspensory ligaments of Cooper- lump is
pulling down the fibers.
 You suspect it is malignant & try to move the
lump while the pt presses her hip with her
hands. Lump movement reduces.
 Involvement of the pectoralis major &
fascia

41.  What directions would you move the
lump?
 Diagonally to the midline

42.  Pt is now undergoing a mastectomy.
Surgeon found LN involvement. He
wants to assess the level of
involvement. What is the landmark
would you choose?
 Pectoralis minor

43.  If she is willing to reconstruct the
breast, what muscles can be used?
 Latissimus dorsi muscle (an LD flap)
 Transversus abdominis muscle (TRAM flap)

44.  Now the Pt has undergone the L/S
mastectomy. She complains of L/S
upper limb swelling.
 Removal of axillary LNs which drains
L/s upper limb lymphatics
 Pt also complains of parasthesia of
the left axillae
 Damage to the left
intercostobrachial nerve

45.  Thank you!