INTRODUCTION:

  • The Mammary Gland is the most important structure present in the pectoral reason.
  • It is found in both sexes but in males it is rudimentary. In females, it is well developed after puberty.
  • The breast is a MODIFIED SWEAT GLAND. It forms an important accessory organ of the female reproductive system.

SITUATION:

  • It lies in the superficial fascia of the pectoral region. It is divided into four quadrants i.e upper lateral, upper medial, lower lateral, lower medial.
  • A small extension of the upper lateral quadrant called the AXILLARY TAIL OF SPENCE passes through an opening in the deep fascia and lies in the Axilla. The opening is called FOREMAN Of LANGER.

EXTENT:

Vertically- it extends from second to the sixth rib.
Horizontally- it extends from the lateral border of sternum to the midaxillary line.

DEEP RELATIONS:

The deep surface of the Breast is related to the following in that order:
  • The Breast lies in the deep fascia (pectoral fascia) covering the pectoralis major.
  • Still deeper there are parts of the three muscles, namely the pectoralis major, serratus anterior and the external oblique muscle of the abdomen.
  • The breast is separated from the pectoral fascia by loop areolar tissue called retro Mammary space.

STRUCTURE OF THE BREAST:

It can be explained in three headings below:

A. Skin:

It covers the Gland and presents the following features:-
  • A conical projections called the NIPPLES, is present just below the center of the breast at the level of fourth intercostal space 10cm from the middle.
  • The nipple is pierced by 15-20 lactiferous ducts.
  • Smooth muscles fines which can make the nipple stiff or flatten it respectively.
  • It has few modified sweat and Sebaceous glands.
  • It is rich in nerve supply.
  • The skin surrounding the base of the nipple is pigmented and forms a circular area called AREOLA.
  • This region is rich in modified SEBACEOUS GLAND, particularly in its outer margin. The skin of areola and nipple is devoid of hairs.

B. Parenchyma:

  • It is a COMPOUND TUBULAR-ALEVOLAR GLAND which secrets milk.
  • It consists of 15-20 lobes. Each lobe is a cluster of alveoli and is drained by a lactiferous duct.
  • The termination of the lactiferous duct has a dilation known as LACTIFEROUS SINUS.
  • Alveolar epithelium is cuboidal during the resting phase and columnar during Lactation, the small ducts are lined by columnar epithelium and the large ducts are lined by two or more layers of cells.
  • The terminal tubule is lined by a stratified squamous keratinized epithelium.
  • The passage of milk from alveoli into along the duct is facilitated by the construction of Myoepitheliocytes.

C. Stroma:

  • It forms the supporting framework of the Gland. It is partly fibrous and partly fatty.
  • The fibrous stroma forms septa known as the SUSPENSORY LIGAMENT OF COOPER Which anchor the skin and gland to the pectoral fascia.
  • The fatty stroma forms the main bulk of the Gland which is distributed all over the Breast except beneath the areola and nipple.

BLOOD SUPPLY:

The Mammary Gland is extremely vascular.
It is supplied by:-
  • INTERNAL THORACIC ARTERY, the branch of the subclavian artery.
  • LATERAL THORACIC, SUPERIOR THORACIC & ACROMIOTHORACIC branches of the Axillary artery.
  • LATERAL BRANCHES of the posterior intercoastal arteries.
  • The arteries coverage on the breast and are distributed from the anterior surface. 
  • The posterior the surface is relatively vascular.

VENOUS DRAINAGE:

  • The superficial veins drains into the internal thoracic vein and into the superficial vein of lower part of the neck.
  • The deep veins drain into the Axillary and posterior intercostal veins.

NERVE SUPPLY:

  • The Breast is supplied by the anterior and lateral cutaneous branches of the 4th to 6th intercostal nerves. The nerves don't control the secretion of milk.
  • Secretion is controlled by the hormone PROLACTIN.

LYMPHATIC DRAINAGE:

It is drainage of the Breast assumes great importance to the surgeon because of carcinoma of the breast spread mostly along lymphatics to the regional lymph nodes.

Lymph Nodes:

Lymph from Brest drains into following lymph nodes:
  • Axillary Lymph Nodes : Mainly the anterior Axillary group. The Posterior, lateral, central and the apical group also receive Lymph directly or indirectly.
  • Supraclavicular Nodes, Cephalic Nodes and Posterior Intercoastal Nodes and Suprasterneal Lymph plexus.
  • Internal Mammary Nodes: Which lie along the internal thoracic vessels.
  • Lymphatic Vessel:
  • Superficial Lymphatics:  It drains the skin over the breasts except for the nipple and areola.
  • Deep Lymphatics: It drains the parenchyma of the breast. It also drains nipple and areola.
  • About 75% of the lymph from the breast drains into Axillary Nodes, 20 % of internal Mammary Nodes and 5% Posterior internal nodes.
  • The internal Mammary Nodes drain the Lymph not only from the inner half of the breast but from the outer half as well.
  • A plexus of lymph vessels are present deep to the areola. This is the subareolar plexus of SAPPEY. It drains into the anterior group of Lymph Nodes.
  • Lymphatics from the lower and inner quadrant of the breast may communicate with the subdiaphragmatic and subperiosteal Lymph plexuses.

CLINICAL ANATOMY:

  • The upper and outer quadrant of breast is a frequent site of cancer.
  • Infiltration of LACTIFEROUS ducts and their consequent fibrosis can cause retraction of the nipples.
  • Obstruction of the superficial Lymph vessels by cancer cells may produce edema of the skin giving rise to an appearance like that of the skin of an orange.
  • Fine needle aspiration cytology is a safe and quick method of diagnosis of lesion of Breast.
  • Cancer of the Mammary Glands in the most common cancer in all females of all ages.
  • Abnormalities of the Breast are:

a. Amastia:- Absent of Breast.
b. Athelia:- Absence of Nipple.
c. Polymastia:- Supernumerary breast.
d. Polythelia:- Supernumerary Nipple.
e. Gynecomastia:- Development of Brest in males.