16.2 – Anatomy of the Breast and Axilla Flashcards
Where are the breasts located?
- horizontal and vertical span?
- Which 2 muscles does it lie superficially to?
- The breast is located on the anterior thoracic wall.
- It extends horizontally from the lateral border of the sternum to the mid-axillary line.
- Vertically, it spans between the 2nd-6th costal cartilages (sternal angle to xiphisternum).
- It lies superficially to the pectoralis major and serratus anterior muscles.
- In the subcutaneous tissue (superficial fascia) of the anterior thoracic wall.
What allows for movement of the breast & space for breast implants?
Retromammary space b/w posterior capsule & pectoralis major = allows movement & space for breast prosthesis.
What are the 2 regions of the breast (surface anatomy)?
The breast can be considered to be composed of two regions:
- Circular body – largest and most prominent part of the breast.
- Axillary tail – smaller part, runs along the inferior lateral edge of the pectoralis major towards the axillary fossa.
What is the Anatomical Structure of the Breast?
- What type of gland are mammary glands?
- What are the suspensory ligaments of Cooper? 2 Functions?
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Anatomical Structure of the Breast
The breast is composed of mammary glands surrounded by a connective tissue stroma.
Mammary Glands
- The mammary glands are modified sweat glands. They consist of a series of ducts and secretory lobules (15-20).
- Each lobule consists of many alveoli drained by a single lactiferous duct.
- These ducts converge at the nipple like spokes of a wheel.
Connective Tissue Stroma
- The connective tissue stroma is a supporting structure which surrounds the mammary glands. It has a fibrous and a fatty component.
- The fibrous stroma condenses to form suspensory ligaments (of Cooper).
- These ligaments have two main functions:
- Attach and secure the breast to the dermis and underlying pectoral fascia.
- Separate the secretory lobules of the breast.
Pectoral Fascia
- The base of the breast lies on the pectoral fascia – a flat sheet of connective tissue associated with the pectoralis major muscle. It acts as an attachment point for the suspensory ligaments.
- There is a layer of loose connective tissue between the breast and pectoral fascia – known as the retromammary space. This is a potential space, often used in reconstructive plastic surgery.
Where is the nipple usually located?
Which muscle fibres make up the nipple?
Nipple usually over the 4th intercostal space.
At the centre of the breast is the nipple, composed mostly of smooth muscle fibres.
What is peau d’orange? Which ligaments cause it?
What 3 things does the areola contain?
- What are the tubercles of Montgomery?
Areola contains:
- Apocrine sweat glands
- Sebaceous (areolar) glands (may form small bumps – tubercles of Montgomery)
- Few hair follicles.
What are the quadrants of the breast?
Breast Quadrants:
Intersect in the middle of the nipple (UO, LO, UI, LI, nipple = 5th quadrant).
Upper outer – may extend into the axilla as an axillary tail, most of the breast lies here.
Lesions described according to which quadrant they lie in, their position on a clock face
centred on the nipple & their distance from the edge of the areola.
What is the blood supply of the breast?
Medial Aspect = internal thoracic artery (also known as internal mammary artery) – a branch of the subclavian artery.
The lateral part of the breast receives blood from four vessels:
- Lateral thoracic and thoracoacromial branches – originate from the axillary artery.
- Lateral mammary branches – originate from the posterior intercostal arteries (derived from the aorta). They supply the lateral aspect of the breast in the 2nd 3rd and 4th intercostal spaces.
- Mammary branch – originates from the anterior intercostal artery.
The veins of the breast correspond with the arteries, draining into the axillary and internal thoracic veins.
What is the venous drainage of the breast?
Describe the route for malignant cells in breast cancer – secondaries in spine.
What is the nerve supply to the breast and nipple?
What is the lymphatic drainage of the breast?
There are three groups of lymph nodes that receive lymph from breast tissue – the axillary nodes (75%), parasternal nodes (20%) and posterior intercostal nodes (5%).
