Breast
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Breast
- Consists of mammary gland tissue, fibrous and fatty tissue, blood and lymph vessels, and nerves.
- Extends from the second to sixth ribs and from the sternum to the midaxillary line and is divided into the upper and lower lateral and medial quadrants.
- Has mammary glands, which lie in the superficial fascia.
- Is supported by the suspensory ligaments (Cooper's ligaments) , which are strong fibrous processes that run from the dermis of the skin to the deep layer of the superficial fascia through the breast.
- Has a nipple , which usually lies at the level of the fourth intercostal space.
- Has an areola , which is a ring of pigmented skin around the nipple.
- Receives blood from the medial mammary branches of the anterior perforating branches of the internal thoracic artery, the lateral mammary branches of the lateral thoracic artery, the pectoral branches of the thoracoacromial trunk, and the lateral cutaneous branches of the posterior intercostal arteries.
- Is innervated by the anterior and lateral cutaneous branches of the second to sixth intercostal nerves.
- May have presence of more than one pair of breasts (polymastia), more than one pair of nipples (polythelia), absence of breasts (amastia), and absence of nipples (athelia).
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Mammary gland
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- Is a modified sweat gland located in the fatty superficial fascia.
- Has the axillary tail , a small part of the mammary gland that extends superolaterally sometimes through the deep fascia to lie in the axilla.
- Is separated from the deep fascia covering the underlying muscles by an area of loose areolar tissue known as the retromammary space , which allows the breast some degree of movement over the pectoralis major muscle.
- Has 15 to 20 lobes of glandular tissue, which are separated by fibrous septa that radiate from the nipple. Each lobe opens by a lactiferous duct onto the tip of the nipple, and each duct enlarges to form a lactiferous sinus , which serves as a reservoir for milk during lactation.
- Usually warrants radial incisions to avoid spreading any infection and damaging the lactiferous ducts.
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Lymphatic drainage
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- Removes lymphatic fluid from the lateral quadrants into the axillary nodes and the medial quadrants into the parasternal (internal thoracic) nodes.
- Drains primarily (75%) to the axillary nodes, more specifically to the pectoral (anterior) nodes (including drainage of the nipple).
- Follows the perforating vessels through the pectoralis major muscle and the thoracic wall to enter the parasternal (internal thoracic) nodes , which lie along the internal thoracic artery.
- Also drains to the apical nodes and may connect to lymphatics draining the opposite breast and to lymphatics draining the anterior abdominal wall.
- Is of great importance in view of the frequent development of cancer and subsequent dissemination of cancer cells through the lymphatic stream.
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Axilla
| Axilla
- Is a pyramidal region between the upper thoracic wall and the arm.
Boundaries of the axilla
- Medial wall: upper ribs and their intercostal muscles and serratus anterior muscle.
- Lateral wall: humerus.
- Posterior wall: subscapularis, teres major, and latissimus dorsi muscles.
- Anterior wall: pectoralis major and pectoralis minor muscles.
- Base: axillary fascia.
- Apex: interval between the clavicle, scapula, and first rib.
Contents of the axilla
- Include the axillary vasculature, branches of the brachial plexus, lymph nodes, and areolar tissue.
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