The breast is a modified apocrine sweat gland, also known as the mammary gland, specialized for milk production and lactation in females.

Where is the breast anatomically located?

The breast lies in the superficial fascia of the anterior chest wall, extending from the 2nd to the 6th rib and from the lateral border of the sternum to the mid-axillary line.

What is the axillary tail of the breast?

The axillary tail, also called the Tail of Spence, is a lateral extension of breast tissue into the axilla and is clinically important in breast cancer spread.

How many lobes are present in a normal breast?

A normal adult breast contains approximately 15–20 lobes arranged radially around the nipple.

What are Cooper’s ligaments?

Cooper’s ligaments are fibrous connective tissue bands that extend from the skin to the deep fascia, helping maintain the shape and structural integrity of the breast.

What is the primary function of the nipple?

The nipple contains openings of lactiferous ducts and serves as the exit point for milk during lactation.

Which tissue is absent beneath the nipple and areola?

Adipose (fat) tissue is absent beneath the nipple and areola.

What is the main arterial supply of the breast?

The breast receives blood from the internal thoracic artery, lateral thoracic artery, thoracoacromial artery, and posterior intercostal arteries.

What is the major lymphatic drainage pathway of the breast?

Approximately 75% of breast lymph drains into the axillary lymph nodes, especially the anterior (pectoral) group.

What is Sappey’s plexus?

Sappey’s plexus is a subareolar lymphatic network that plays a key role in lymph drainage from the nipple and areola.

Which nerve supplies sensation to the nipple?

The nipple is mainly supplied by the fourth intercostal nerve (T4).

What is the retromammary space?

The retromammary space is a loose connective tissue plane between the breast and pectoral fascia that allows free mobility of the breast.

From which embryological structure does the breast develop?

The breast develops from the mammary ridge, also known as the milk line.

Polymastia refers to the presence of accessory breast tissue, usually occurring along the milk line.

What hormonal changes occur in the breast during pregnancy?

During pregnancy, estrogen promotes ductal growth while progesterone stimulates lobuloalveolar development.

Which hormone is responsible for milk secretion?

Prolactin is responsible for milk production in the alveoli of the breast.

Which hormone causes milk ejection?

Oxytocin causes contraction of myoepithelial cells leading to milk ejection.

Why does breast carcinoma spread easily?

Breast carcinoma spreads easily due to rich lymphatic drainage and absence of a well-defined deep fascial barrier.

What causes peau d’orange appearance in breast cancer?

Peau d’orange occurs due to lymphatic obstruction leading to skin edema and pitting.

What is gynecomastia?

Gynecomastia is the benign enlargement of male breast tissue due to hormonal imbalance, particularly increased estrogen activity.

Breast Anatomy Detailed Structure Blood Supply Lymphatic Drainage Clinical Correlation

Breast Anatomy (Mammary Gland)

1. Definition and Overview

The breast (mammary gland) is a modified apocrine sweat gland, specialized for lactation. It is present in both sexes but is functionally developed in females after puberty under hormonal influence.

2. Location and Extent

Lies in the superficial fascia of the anterior chest wall
Vertical extent: 2nd to 6th ribs
Horizontal extent: Lateral border of sternum → mid-axillary line
Axillary tail (Tail of Spence): Extension into axilla through foramen of Langer (important in breast cancer spread)

3. External Features

(A) Nipple

Located at the level of the 4th intercostal space in nulliparous females
Contains 15–20 openings of lactiferous ducts
No fat, hair, or sweat glands
Rich in smooth muscle → erection with stimulation

(B) Areola

Circular pigmented area around nipple
Contains Montgomery’s tubercles (modified sebaceous glands)
Darkens during pregnancy

4. Internal Structure (Gross Anatomy)

(A) Lobes and Lobules

15–20 lobes arranged radially
Each lobe → subdivided into lobules
Lobules contain alveoli (acini) → milk-secreting units

(B) Duct System

Alveoli → intralobular ducts → interlobular ducts
Each lobe drains via a lactiferous duct
Lactiferous duct shows slight dilatation near nipple (lactiferous sinus – minimal in humans)

5. Supporting Structures

(A) Fibrous Tissue

Suspensory ligaments of Cooper
Extend from skin → deep fascia
Maintain breast shape
Shortening causes skin dimpling (important sign in carcinoma)

(B) Fat

Determines size and shape of breast
Absent beneath nipple and areola

6. Relations

Skin and superficial fascia

Posterior

Pectoral fascia over:

* Pectoralis major

* Serratus anterior (laterally)

Retromammary space: Allows mobility of breast over chest wall

7. Blood Supply

Arterial Supply

Internal thoracic artery (perforating branches)
Lateral thoracic artery
Thoracoacromial artery
Posterior intercostal arteries

Venous Drainage

Axillary vein
Internal thoracic vein

8. Lymphatic Drainage (Very Important)

75% → Axillary lymph nodes

* Anterior (pectoral)

* Central

* Apical

Medial quadrants → Parasternal nodes
Some drainage → posterior intercostal nodes
Subareolar plexus (Sappey’s plexus) plays key role

9. Nerve Supply

Intercostal nerves T2–T6
Nipple mainly supplied by T4
Sensory supply to skin and nipple
Sympathetic fibers to blood vessels and smooth muscle

10. Developmental Anatomy

Develops from mammary ridge (milk line) extending from axilla to groin
Persistence → accessory breast or nipple (polythelia, polymastia)

11. Changes with Age and Hormones

Puberty

Estrogen → ductal growth
Progesterone → lobuloalveolar development

Pregnancy

Proliferation of alveoli
Increased vascularity

Lactation

Prolactin → milk secretion
Oxytocin → milk ejection

Menopause

Glandular tissue replaced by fat
Breast becomes less dense

12. Applied Anatomy (Clinical Importance)

Breast carcinoma spreads via lymphatics
Peau d’orange: Lymphatic obstruction
Retraction of nipple: Involvement of lactiferous ducts
Mastitis: Infection during lactation
Gynecomastia: Male breast enlargement

13. Key Exam Points (Quick Recall)

Tail of Spence → axillary extension
Cooper’s ligaments → skin dimpling
Main lymph drainage → axillary nodes
Nipple nerve supply → T4
Milk line anomalies → accessory breast/nipple