Anatomy III: Blood and Glands

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Questions and Answers

What is the primary arterial supply to the breast?

Brachial artery

Femoral artery

Subclavian artery (correct)

Common carotid artery

Which statement is true regarding the lymphatic drainage of the breast?

All lymph from the breast drains to the bronchomediastinal trunks

Lymph from the breast does not drain to the opposite side

The majority of lymph drains to the axillary lymph nodes (correct)

Parasternal lymph nodes drain all lymph from the lateral quadrants

What role do the anterior and lateral cutaneous branches of intercostal nerves play in the breast?

They supply sensory fibers to the breast skin (correct)

They provide motor function to the breast muscles

They innervate the thoracic cavity

They are responsible for lymphatic drainage

What is a consequence of a minor congenital anomaly in the breast?

Difficulty in breastfeeding Signup and view all the answers

Which veins are primarily responsible for the venous drainage of the breast?

Axillary and internal thoracic veins Signup and view all the answers

How much lymph drains from the breast to the parasternal lymph nodes?

25% Signup and view all the answers

From where does lymph pass after draining into the axillary nodes?

To the clavicular lymph nodes Signup and view all the answers

What are sympathetic fibers in the breast responsible for?

Blood vessel regulation Signup and view all the answers

What primarily determines the size of non-lactating breasts?

Quantity of fatty matrix Signup and view all the answers

What anatomical structure represents the upper limit of the female breast?

Superior surface with no sharp demarcation Signup and view all the answers

During which life stage do breasts primarily enlarge due to glandular development and increased fat deposition?

Female puberty Signup and view all the answers

What are the suspensory ligaments of Cooper responsible for?

Attaching the mammary gland to the skin Signup and view all the answers

Which hormone is primarily responsible for the enlargement of glandular tissue during the menstrual period?

Luteinizing hormone (LH) Signup and view all the answers

In male breasts, which anatomical feature is accurately described?

They consist of small ducts or epithelial cords Signup and view all the answers

What anatomical structure allows movement of the breast on the pectoral fascia?

Retromammary space Signup and view all the answers

What is true about the mammary glands?

They are modified sweat glands without a capsule Signup and view all the answers

What anatomical feature forms the anterior axillary fold in athletic men?

Lateral border of the breasts Signup and view all the answers

What limits the movements of the mammary glands?

Suspensory ligaments of Cooper Signup and view all the answers

What is the primary function of the lactiferous sinus?

To accumulate milk droplets Signup and view all the answers

Which statement about areolae is accurate?

They secrete an oily substance for lubrication. Signup and view all the answers

How does the nipple respond when a baby suckles?

It compresses the lactiferous ducts. Signup and view all the answers

What change happens to the areola during pregnancy?

It enlarges and darkens. Signup and view all the answers

What is NOT a characteristic of the nipples?

They contain fat and hair. Signup and view all the answers

What initiates the hormonal let-down reflex during breastfeeding?

Compression of the areola and lactiferous sinus. Signup and view all the answers

Where is the nipple typically located in young nulliparous women?

4th intercostal space, 10 cm from the axillary midline Signup and view all the answers

What feature of the lactiferous ducts is significant during nursing?

They converge at the areola. Signup and view all the answers

Study Notes

Anatomy III: Blood and the Cardiovascular and Respiratory Systems

This is a course on the anatomy of the blood and cardiovascular and respiratory systems.

Lesson 5: Mammary Glands

Mammary glands are present in both males and females, but fully develop in women.
In men, mammary glands consist of small ducts and epithelial cords. The glandular system does not fully develop.
Male breast tissue is similar to subcutaneous tissue.
Breasts mostly follow the contour of the pectoralis major muscles.
The nipple is located in the 4th intercostal space, lateral to the midclavicular line.
In athletic men, the pectoralis major muscles are more apparent, revealing intermammary clefts overlying the sternum and lateral borders forming the anterior axillary fold.

Breasts in Women

Functionally, breasts are accessory to reproduction.
The superior boundary of the breast is a flattened surface, not sharply demarcated from the thoracic wall.
Lateral and inferior boundaries are the submammary sulcus.
Breast tissue is comprised of glandular and supporting fibrous tissue, embedded in a fatty matrix, containing vessels, lymphatics and nerves.

Breasts in Men

In athletic men, the contour of the pectoralis major muscles is noticeable.
Topographic lines can be seen, such as the intermammary cleft above the sternum and the lateral border marking the axillary fold.

Bed of the Breast

The breast bed is formed by pectoralis major and serratus anterior fasciae.
The lateral limits run from the lateral border of the sternum to the midaxillary line, and the vertical limits from the 2nd to 6th rib.

Retromammary Space

The retromammary space is a potential space between the breast and the pectoral fascia, filled with loose subcutaneous tissue.
This allows breast movement over the pectoral fascia.

Suspensory Ligaments of Cooper

These skin ligaments attach to the dermis of the overlying skin, particularly well-developed in the superior part of the gland.
They support the lobes and lobules of the mammary gland.
They extend from the infero-lateral edge of the pectoralis major muscle toward the axillary fossa.

Change of Breast Size

Breast size and shape vary based on genetics, ethnicity, and diet. It changes throughout life.
Puberty (8-15 years) causes enlargement due to glandular development and fat deposition. The areola and nipples also enlarge.
The menstrual cycle leads to slight glandular enlargement due to hormonal changes from LH and FSH.
Pregnancy causes mammary gland and new glandular tissue enlargement.

Mammary Glands (Structure)

Mammary glands are modified sweat glands.
They lack a capsule or sheath.
Milk-secreting alveoli are clustered.
Mammary glands enlarge when FSH and LH hormones are released, such as during monthly menstrual cycles.

Structure of the Breast

Lobules form the breast parenchyma, each drained by a lactiferous duct.
Lactiferous ducts converge to open into the areola.
The final portion of the ducts forms the lactiferous sinus, where milk accumulates.
Neonatal sucking stimulates compression of the areola and lactiferous sinus releasing accumulated milk.
Neonatal sucking stimulates hormonal let-down reflex encouraging continued nursing.

Areolae

Contain numerous sebaceous glands.
Enlarge during pregnancy, providing a protective oily lubricant for the areola and nipple.
Areola usually darkens during pregnancy and maintains this pigmentation.
Areola is dotted with openings from areolar glands (sebaceous glands).

Nipples

Nipples lack fat, hair, and sweat glands.
Mostly composed of circular smooth muscle fibers.
Functions: compress lactiferous ducts during lactation, erect in response to stimulation (like during sucking).
In young women (nulliparous), the nipple is typically located at the 4th intercostal space, 10cm from the axillary midline. This is not a reliable location in all adults.
Nipple inversion/retraction can be a minor congenital anomaly making breastfeeding difficult.

Arterial Supply

Blood supply comes from various arteries: subclavian, internal thoracic artery (with anterior intercostal and medial mammary branches), axillary artery (lateral thoracic and thoraco-acromial arteries), and thoracic aorta (posterior intercostal arteries).

Venous Drainage

Breast veins drain into: internal thoracic vein, axillary vein.
The venous pattern over breasts may be visible through skin, particularly during pregnancy.

Lymphatics of the Breast

Lymph from the nipple, areola, and lobules drains to the subareolar lymphatic plexus.
~75% of plexus lymph drains to axillary lymph nodes.
~25% drains to parasternal lymph nodes or to opposite breast.
Axillary nodes drain into clavicular nodes and eventually into the subclavian lymphatic trunk.
Parasternal nodes drain into the bronchomediastinal lymphatic trunks and then to the thoracic duct.

Nerves of the Breast

Nerves coming from the 4th, 5th and 6th intercostal nerves (anterior and lateral) penetrate the pectoral fascia to reach the subcutaneous tissue.
Nerves provide sensory innervation to breast skin and sympathetic innervation to blood vessels and smooth muscle of skin/nipple.

Bibliography

Various anatomical texts are referenced including publications from Moore, Drake, Rohen, and Yokochi.

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Description

Explore the intricacies of the blood, cardiovascular, and respiratory systems, along with an in-depth look at mammary glands in both males and females. This quiz covers essential information regarding the structure and function of these systems and their anatomical features.