Podcast
Questions and Answers
Which of the following muscles is NOT directly involved in the movement of the pectoral girdle?
Which of the following muscles is NOT directly involved in the movement of the pectoral girdle?
What is the anatomical landmark formed by the inferior border of the Pectoralis Major muscle?
What is the anatomical landmark formed by the inferior border of the Pectoralis Major muscle?
Which of the following muscles is responsible for stabilizing the clavicle?
Which of the following muscles is responsible for stabilizing the clavicle?
Which muscle forms a passage for vessels, nerves, and the lateral thoracic artery?
Which muscle forms a passage for vessels, nerves, and the lateral thoracic artery?
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The Serratus Anterior muscle is named for its:
The Serratus Anterior muscle is named for its:
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Which of the following muscles is responsible for depressing and anchoring the clavicle?
Which of the following muscles is responsible for depressing and anchoring the clavicle?
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The serratus anterior muscle originates from which specific location on the ribs?
The serratus anterior muscle originates from which specific location on the ribs?
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Which of the following is NOT a function of the serratus anterior?
Which of the following is NOT a function of the serratus anterior?
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What is the main nerve that innervates the serratus anterior muscle?
What is the main nerve that innervates the serratus anterior muscle?
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The Pectoralis major muscle has two heads; what are they?
The Pectoralis major muscle has two heads; what are they?
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Which of the following structures is NOT directly involved in the lymphatic drainage of the breast?
Which of the following structures is NOT directly involved in the lymphatic drainage of the breast?
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During lactation, which smooth muscle fibers in the breast are responsible for compressing the lactiferous ducts?
During lactation, which smooth muscle fibers in the breast are responsible for compressing the lactiferous ducts?
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Which of the following arteries is NOT involved in the arterial supply of the breast?
Which of the following arteries is NOT involved in the arterial supply of the breast?
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What is the primary reason for the enlargement of female breasts during puberty?
What is the primary reason for the enlargement of female breasts during puberty?
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The suspensory ligaments of Cooper are primarily responsible for:
The suspensory ligaments of Cooper are primarily responsible for:
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The retromammary space is a potential space located between:
The retromammary space is a potential space located between:
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Which of the following statements is TRUE regarding the anatomical location of the female breast?
Which of the following statements is TRUE regarding the anatomical location of the female breast?
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In the female breast, the parenchyma is composed of _________ while the stroma is composed of _______.
In the female breast, the parenchyma is composed of _________ while the stroma is composed of _______.
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Which of the following clinical conditions involves the enlargement of male breast tissue?
Which of the following clinical conditions involves the enlargement of male breast tissue?
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The lymph nodes that receive most of the lymphatic drainage from the lateral quadrants of the breast are the:
The lymph nodes that receive most of the lymphatic drainage from the lateral quadrants of the breast are the:
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Study Notes
Pectoral Region
- The pectoral region is located on the anterior chest wall
- It comprises four muscles that move the pectoral girdle: pectoralis major, pectoralis minor, subclavius, and serratus anterior
Pectoralis Major
- The largest and superior muscle of the anterior chest wall
- A thick, fan-shaped muscle beneath the breast tissue
- Forms the anterior wall of the axilla
- Has clavicular and sternocostal heads
- Its inferior border forms the anterior axillary fold
- Works together with the deltoid
Pectoralis Minor
- Lies in the anterior chest wall, mostly covered by the pectoralis major
- Triangular in shape
- Its base is formed by fleshy slips attached to the 3rd-5th ribs near their coastal cartilages
- Apex connects to the coracoid process of the scapula
- This muscle is a useful anatomical and surgical landmark for axillary structures, like the axillary artery
- Creates a passage for vessels
Pectoralis Minor in Relation to Vessels and Nerves
- Diagrams show the muscle's location relative to vessels and nerves in the axillary region
Subclavius
- Almost horizontally positioned in anatomical position
- A small, triangular muscle between the first rib and clavicle
- Stabilizes the clavicle and protects the subclavian vessels and brachial plexus
- Helps prevent clavicle dislocation at sternoclavicular joint
Serratus Anterior
- Named for its "saw-toothed" appearance
- A fan-shaped muscle
- Originates on the superolateral surfaces of the first to eighth ribs
- Inserts along the anterior surface of the medial border of the scapula, including the inferior angle
- Holds the scapula against the thoracic wall during movements like push-ups
Pectoral Muscles
- Detailed descriptions of proximal and distal attachments, innervation, and main actions of each pectoral muscle (pectoralis major, pectoralis minor, subclavius, and serratus anterior)
- Includes specific nerves like medial pectoral, nerve to subclavius and long thoracic nerve
The Breasts
- The most prominent superficial structure in the anterior thoracic wall
- Composed of glandular, supportive fibrous tissue, embedded in a fatty matrix, with blood vessels, lymphatics, and nerves.
- Well-developed only in females
- The nipple is the most prominent part of the breast
The Mammary Glands
- Located in the subcutaneous tissue overlying the pectoralis major and minor muscles
- Accessory to reproduction in women
- Rudimentary and functionless in men, with only a few ducts or cords.
- The fat in male breasts is similar to subcutaneous tissue elsewhere. In females the glandular system rarely fails to develop
- The glandular tissue within the female breasts increases in volume following puberty.
The Female Breasts
- Roughly circular shape, resting on the sternum, extending from the lateral border of sternum to midaxillary line
- Vertically runs from the second to sixth ribs, including the axillary tail of Spence (axillary process)
- Minor portion extends along the inferolateral edge of the breast
Extent of the Breast
- 2/3 of the breast rests on deep pectoral fascia overlying the pectoralis major
- 1/3 rests on the fascia covering the serratus anterior muscle
- The space between the breast and pectoral fascia is the retromammary space
Retromammary Space
- A loose subcutaneous tissue/potential space
- Contains a small amount of fat
- Allows breast movement over the pectoral fascia
Structure of breast tissue (layers)
- Describes the layers within the breast, including the epidermis, dermis, Cooper's ligaments, breast ducts, and retromammary space and other components of the breast
Suspensory Ligaments of Cooper
- Dense fibrous connective tissue bands supporting the lobes and lobules of the mammary gland.
- Well-developed in the superior part of the gland
- Help support the lobes and lobules during puberty in females
The Glandular Tissue of the Breast
- Lactiferous ducts give rise to 15-20 lobules of mammary gland parenchyma
- Each lobule drains into a lactiferous duct
- These ducts converge towards the nipple (like spokes on a wheel)
- Deep to the nipple, the ducts enlarge (in lactiferous sinuses)
Areolae
- Contains numerous sebaceous glands that enlarge during pregnancy
- Secrete an oily substance lubricating the areola and nipple
Nipples
- Conical/cylindrical prominences in the centre of the areola
- Lack fat, hair, and sweat glands.
- Fissured tips that contain opening of lactiferous ducts
- Mostly composed of smooth muscle that compresses the ducts during lactation
Mammary Glands
- Modified sweat glands, without a capsule
- Breast contour primarily composed of fat, except during pregnancy when glandular tissue develops
- Milk-secreting alveoli form clusters resembling grapes
- Breast size and composition may vary depending on factors like menstrual cycle or pregnancy
Blood Supply of Breasts
- Arterial supply: internal thoracic, lateral thoracic, thoracoacromial, and posterior intercostal arteries
- Venous return: axillary, internal thoracic, and intercostal veins
Lymphatic Drainage of Breasts
- Very important due to metastasis
- Lymph from nipples, areola, and lobules gathers in a subareolar plexus
- Most lymph (75%) drains from the lateral quadrants through axillary nodes to pectoral nodes
- Some lymph drains directly into the deltopectoral/supraclavicular/interpectoral/inferior deep nodes
Clinical Anatomy of Breasts
- Breast quadrants
- Carcinoma (breast cancer)
- Mastectomy
- Gynecomastia
- Polymastia, polythelia, and amastia
- Mammography
Mammogram Types
- Images demonstrating fatty, scattered fibroglandular, heterogeneously dense, and extremely dense breast tissue
Mammogram Examples
- Images showing normal, benign cyst, cancer, and calcification in the breasts
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Description
Test your knowledge on the anatomy of the pectoral region, including the muscles that comprise this area and their functions. Learn about the pectoralis major and minor, as well as their anatomical significance in relation to vessels and nerves. This quiz is an essential resource for understanding the muscular framework of the chest.
