The Breast

Question 1

What is a mammary gland?

Answer 1

The mammary gland is a modified sweat gland present in the
superficial fascia of the pectoral region.

Question 2

Identify the location of the breast.

Answer 2

The breast is located in the superficial fascia of the pectoral
region. A small extension from its superolateral part
(axillary tail of Spence) however pierces the deep fascia
and extends into the axilla. The aperture in the deep fascia
through which axillary tail passes into the axilla is called
foramen of Langer. The axillary tail is the site of high
percentage of breast tumor.

Question 3

Describe the shape and extent of the breast

Answer 3

Shape: Hemispherical bulge.
Extent:
1. Vertically, it extends from 2nd rib to 6th rib.
2. Horizontally, it extends from lateral border of the
sternum to the midaxillary line.

Question 4

What structures are related to the deep aspect of the breast.

Answer 4

1. pectoral fascia
2. Three muscles: Pectoralis major, serratus anterior and the external oblique muscle.

Question 5

Describe the 3 structures of the breast.

Answer 5

(A) Skin: It is the covering for the breast and presents the
following features:
1. Nipple: It is a conical projection below the center of the
breast, usually at the level of the 4th intercostal space.
2. Areola: It is the circular area of pigmented skin
surrounding the base of the nipple. It contains large
number of modified sebaceous glands, particularly at its
outer margin. They produce oily secretion, which
lubricates the nipple and areola, and thus prevents them
from drying and cracking.
(B) Stroma: The stroma of breast consists of connective tissue
and fat. It forms the supporting framework of the breast.
The connective tissue condenses to form fibrous strands/
septa, called suspensory ligaments of Cooper which maintain the protuberance of the breast.
(C) Parenchyma/glandular tissue/mammary gland proper: The parenchyma/glandular tissue of the breast
secrete milk to feed the newborn baby. It consists of about
15–20 lobes arranged in a radial fashion like the spokes of a
wheel and converge towards the nipple. Each lobe is divided into lobules which consist of cluster of acini. Each lobe is drained by a lactiferous duct. Each duct expands into a lactiferous sinus, which serves as a reservoir for milk during lactation.

Question 6

Identify the arterial supply of the breast.

Answer 6

1. Axillary artery through the superior thoracic artery, acromiothoracic artery and lateral thoracic artery.
2. Lateral branches of the posterior intercostal arteries.
3. Perforating branches of the internal thoracic (mammary) artery.

Question 7

Identify the nerve supply of the breast.

Answer 7

The nerve supply to the breast is primarily somatosensory derived from the 2nd - 6th intercostal nerves through their anterior and lateral cutaneous branches.

Question 8

Identify the venous drainage of the breast

Answer 8

1. Axillary vein
2. Posterior intercostal veins
3. Internal thoracic vein

Question 9

Identify the lymph nodes draining the breast.

Answer 9

1. Axillary lymph nodes
2. Internal mammary lymph nodes
3. Supraclavicular nodes
4. Posterior intercostal nodes
5. Cephalic (deltopectoral) nodes

Question 10

Describe the superficial and deep lymphatic drainage of the breast.

Answer 10

Superficial lymphatics: drain the skin of the breast except that of nipple and areola.
Deep lymphatics: drain the parenchyma of the breast, and skin of the nipple and areola. A plexus of lymph vessels deep to the areola is called subareolar plexus of Sappey. The subareolar plexus and most of the lymph from the breast drain into the anterior group of axillary lymph nodes.
The lymphatic drainage from the breast occurs as follows:
1. The lymph from lateral quadrants of the breast is
drained into anterior axillary or pectoral group of lymph nodes. These lymph nodes are situated deep to the lower border of pectoralis minor.
2. The lymph from medial quadrants is drained into
internal mammary lymph nodes situated along the
internal mammary artery. Some lymphatics may go to
the internal mammary lymph nodes of the opposite side.
3. A few lymph vessels from the lower lateral quadrant of the breast follow the posterior intercostal arteries and drain into posterior intercostal nodes located along the course of these arteries.
4. The few lymph vessels from the lower medial quadrant of the breast pierce the anterior abdominal wall and communicate with subdiaphragmatic and subperitoneal lymph plexuses.
5. The lymph vessels from the deep surface of the breast pierce pectoralis major and clavipectoral fascia to drain into the apical group of axillary lymph nodes.
N.B. About 75% of the lymph from the breast is drained into axillary nodes, 20% into internal mammary lymph nodes, and 5% into the posterior intercostal lymph nodes.

Question 11

What are the 3 developmental anomalies of the breast

Answer 11

Polythelia/supernumerary nipples, which appear along
the milk ridge and is often mistaken for moles.
* Retracted nipple/inserted nipple, which occurs if nipple
fails to develop from ectodermal pit. In this condition
suckling of infant cannot take place and nipple is prone to
infection.
* Polymastia, the development more than one breast along
the milk line.
* Gynecomastia, the development of breast in male,
mainly at puberty. Usually it is bilateral and thought to
occur due to hormonal imbalance.