Breast Development

Breast Development mainly starts in the 7th week of gestation. Actually it starts thickening along the ridges called as Milk line of Schultz and this milk line of Schultz mainly extends from the axilla to the groin. This is the basic site for the development of the multiple breasts. The presence of breast is along the milk line of Schultz

Common abnormalities that are associated with the development of breast such as:-

• Amastia:- There is a complete absence of breast tissue, nipple as well as areola.
• Amazia:- It’s a situation where the only breast tissue is absent but there is a presence of nipple and areola.
• Polymastia:- It means the presence of multiple breasts, it’s most site is mainly axilla and is mostly associated with Turner syndrome as well as Fleischer’s syndrome.

Common abnormalities that are associated with nipple development are as follows:- 

• Nipple inversion (most common ):- Inverted nipple which is mainly because of subareolar duct shortening. Beside this, it is a common condition which maybe gets back to its normal position most of the time without any treatment that’s why we can say a spontaneous correction is seen in this case. Rarely surgery is required for cosmetics purposes. Somehow mechanical suction devices have been used to evert the nipple with some effect.

This may occur at puberty or later in life. About 25% of cases it is bilateral. It may cause problems with breastfeeding and infection. A slit-like retraction of the nipple may be caused by duct ectasia and chronic periductal mastitis but circumferential retraction might indicate an underlying carcinoma.
• Athelia:- Here there is a complete absence of nipple.
• Polythelia:- Here presence of multiple nipples along the milk line of Schultz.

Others syndromes which are associated with congenital disorders  where the breast is absent such as:- 

Poland syndrome ( Most important):- Here presence of Amazia, absence of a sternal portion of pectoralis major muscle, costal cartilage as well as ribs thus most of the times the hemothorax is completely deformed and along with that there is the presence of brachysyndactly ( Abnormal shortness of fingers or toes combined with webbing between the adjacent digits).

Anatomical structures of breast 

Breast tissue is actually a large sweat gland I.e modified apocrine gland and this modified apocrine gland extends mainly from 2nd rib to 6th rib craniocaudally and from the lateral border of sternum to anterior axillary line. Nipple location commonly at 4th intercostal space. Point to be noted that all the breast tissues there is the presence of hair follicles but there are no hair follicles present over the nipple and areola in the female breast.
The areola contains involuntary muscles arranged in concentric rings as well as radially in the subcutaneous tissue. Montgomery tubercles are the sebaceous tubercles that are present over nipple and areola and those are enlarged during pregnancy and lactation.

The axillary tail of Spence and these are seen passing through a foramen of langer. The functional unit of the breast is called lobule and from lobules, all the secretions come towards the nipple. They are most numerous in young women. From 10-100 lobules empty via ducts into a lactiferous duct, which there are 15-20. The lactiferous duct is provided with a terminal ampulla, a reservoir for milk or abnormal discharges, and excreted through the nipple.

The ligament of Cooper this is hollow conical projections of fibrous tissue filled with breast tissue and this ligament attached to the pectoralis muscles and forming the main framework for breast. These ligaments account for the dimpling of skin overlying a carcinoma.

Breast Development – Physiology

Most important structures are the hormones which help in the physiological development of the breast such as estrogen and progesterone. Estrogen mainly helps in the development of ducts whereas progesterone help in the development of lobules.

Tanner staging of breast development

Blood supply of  Breast 

Mainly 3 arteries 
A. Axillary artery branches – Superior thoracic artery – Acromiothoracic artery – Lateral thoracic artery 
B. The internal mammary artery which supplies to the breast through its branches mainly 2nd, 3rd, and 4th intercostal branches.
C. Intercostal artery 

Venous drainage through 
A. Axillary vein B.Internal mammary vein C. Intercostal vein 

Note :- The posterior intercostal veins which drain breast it has communication to praverebral plexus and this paravertebral plexus communicates with batson plexus and this is the route for spread of breast carinoma cells.
Batson plexus can spread or is attached to the lumbar vertebral veins and also directly assends to the dural sinuses so that cancer cell go to the lumber vertebra or dural sinuses and from dural sinus they get deposited into leptomeninges.

Lymphatic drainage
A. Axillary group of lymph nodes are drain approximately 75 %.
• Anterior axillary lymph nodes • posterior axillary lymph nodes • lateral axillary lymph nodes • Central axillary lymph nodes • Apical axillary lymph nodes 
B. Internal mammary nodes 
C. Supraclavicular nodes.

Apart from these breasts has its own lymphatic drainage insides there are two groups of lymphatics.
• Superficial lymphatics:- They mainly drain the skin over the breast except nipple and areola.
• Deep lymphatic:- It’s drain areola and nipple along with breast parenchyma.
Lymphatic communication exists between two breasts leading to the spreading of cancer cells so if there is carcinoma of breast one side then there is a chance of spreading the other side too.

Oncological classification of lymphatic

A. Berg classification:- This classification mainly based upon pectoralis minor muscles .It’s has 3 levels of the group of lymph nodes.
• Level । – lateral and inferior to pectoralis minor muscle. This level includes an anterior , posterior and lateral group of lymph nodes.
• Level ।। – Present deep to the pectoralis minor muscle. Includes central and rotter’s group of axillary lymph nodes.
• Level ।।। – Present medial to the pectoralis minor muscle. Includes Apical (Halsted) group of lymph nodes.
Some important Nerves in relation to breast tissue that might get injured while doing  surgery of breast such nerve are as:- 

• Long thoracic nerve that mainly supplies the serratus anterior muscles and if this damage can cause winging of the scapula .
• Thoracodorsal nerve mainly supplies latissimus dorsi 
• The intercostobrachial nerve which mainly supplies the medial aspect of the upper arm. If there is injury to this nerve then sensation over the medial aspect of upper arm is lost.

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