Breast Anatomy

Breast Layers:
1. Subcutaneous Layer
2. Mammary (glandular) layer

3. Retromammary layer

1st Layer is Subcutaneous Layer:
· Very thin consisting of fat & connective tissue
· Cooper’s Ligaments

2nd Layer – Mammary (Glandular) Layer:
· Functional layer of the breast
· 15-20 lobules radiate from nipple
· Lactiferous ducts - carry milk from acini to nipple
· Fatty tissue
· Cooper’s Ligaments

3rd Layer - Retromammary Layer

· Thin Layer
· Cooper’s Ligaments
· Fatty Tissue

Lobes are the functional portion of the breast. Each lobe contain milk-producing glands called acinus (ancini).
The breast contain literally hundreds of acinus, which resemble the grapes on a vine.

Terminal Ductal Lobular Units (TDLU) are terminal ends of the duct and the acini and are surrounded by loose, dense connective tissue. TDLU’s are usually 1-2 mm in size, not visible on ultrasound.

Cooper’s Ligaments contain connective tissue septa (which form the “skeleton” structure of the breast).

Sonographic Appearance

Boundaries = strong, bright echo reflection
· Skin line
· Nipple
· Retromammary Layer

Subcutaneous fat = hypoechoic
Cooper’s Ligaments = echogenic
Pectoral muscle = low level echoes
Ribs = hyperechoic


Vascular Supply
Main vascular supply = internal mammary and lateral thoracic artery
Venous Drainage = superficial veins that are just under the skin
(these veins can be seen on ultrasound)

Lymphatic System

Importance of evaluating axillary lymph nodes when malignancy is present


The Male BreastMale%20Chest_607.jpg
Gynecomastia – condition in which the ductal elements
hypertrophy during puberty or later in life due to hormonal
fluctuations, disease processes or medications

Increased risk for male patients for breast cancer:

· Klinefelter’s Syndrome
· Male-to-Female Transsexual
· History of prior chest wall irradiation
(especially for Hodgkin’s lymphoma)
· History of orchitis or testicular tumor
· Liver disease
· Genetic predisposition for gene mutation

Physiology of the Breast

Primary function is fluid transportation, secondary to milk production.
Milk is produced within the ancini and carried to the nipple by the ducts.
Breasts are affected by changing hormone levels with menstrual cycle, pregnancy and lactation. Development begins prior to menarch at approximately 16 years old.

During pregnancy, Prolactin is produced by the pituitary gland enables the acinito produce milk.
The delivery of the placenta after birth initiates milk production and the sucking stimulation of the baby initiates the release of
oxytocin which stimulates additional milk production. At the end of lactation, the breast tissue parenchyma involutes (meaning closely coils); therefore breast screening should not be performed until at least 6 months after breastfeeding.

The “milk line” is the anatomic line along which breast tissue. In many women, the breast tissue extends deep into the axilla, which is referred to as the axillary tail of the breast or the

Tail of Spence.**