Breast Anatomy

Question 1

Vascular anatomy:

Answer 1

The blood supply to the breast skin depends on the subdermal plexus, which is in communication with deeper underlying vessels supplying the breast parenchyma.

Question 2

The blood supply is derived from the following:

Answer 2

1. The internal mammary perforators (most notably the 2nd-5th perforators).
2. The thoracoacromial artery.
3. The vessels to serratus anterior.
4. The lateral thoracic artery.
5. The terminal branches of the 3rd to 8th intercostal perforators.

Question 3

The superomedial perforator supply from the internal mammary vessels is particularly robust and accounts for …?

Answer 3

Some 60% of the total breast blood supply.

**This rich blood supply allows for various reduction techniques, ensuring the viability of the skin flaps after surgery.

Question 4

Sensory innervation of the breast is dermatomal in nature:

Answer 4

It is mainly derived from the anterolateral + anteromedial branches of thoracic intercostal nerves T3-T5.

==> Supraclavicular nerves from the lower fibers of the cervical plexus also provide innervation to the upper and lateral portions of the breast.

==> Researchers believe sensation to the nipple derives largely from the LATERAL CUTANEOUS BRANCH OF T4.

Question 5

Breast parenchyma is made-up of …?

Answer 5

Fatty tissue + Glandular, milk-producing tissues.

Question 6

The ratio of fatty tissue to glandular tissue varies among individuals. In addition, with the onset of menopause …?

Answer 6

Ie, decrease in estrogen levels.

The relative amount of fatty tissue increases as the glandular tissue diminishes.

Question 7

The base of the breast overlies the …?

Answer 7

Pectoralis major muscle between the 2nd-6th ribs in the nonptotic state.

Question 8

The gland is anchored to the pec major fascia by the …?

Answer 8

SUSPENSORY LIGAMENTS first described by Astley Cooper in 1840.

Question 9

The Cooper ligaments run throughout the breast tissue parenchyma …?

Answer 9

From the deep fascia beneath the breast and attach to the dermis of the skin.

**They are not taut ==> allow for the natural position of the breast.

==> Relax with age and time, eventually resulting in breast ptosis.

Question 10

The lower pole of the breast …?

Answer 10

Is fuller than the upper pole.

Question 11

The tail of …?

Answer 11

SPENCE ==> extends obliquely up into the medial wall of the axilla.

Question 12

Which other muscle does the breast overlie?

Answer 12

Inferomedially ==> RECTUS ABDOMINIS MUSCLE.

Question 13

The position of the nipple:

Answer 13

Should lie above the inframammary crease and is usually level with the 4th rib and just lateral to the midclavicular line.

Question 14

The average nipple-to-sternal notch measurement in a youthful, well-developed breast is …?

Answer 14

21-22cm.

**an equilateral triangle formed between the nipples and sternal notch measures an average of 21cm per side.

Question 15

Musculature related to the breast:

Answer 15

1. Pec major.
2. Serratus anterior.
3. External oblique.
4. Rectus abdominis fascia.

**the blood supply that provides circulation to these muscles perforates through to the breast parenchyma, thus also supplying blood to the breast.

Question 16

By maintaining continuity with the underlying musculature, the breast tissue …?

Answer 16

Remains richly perfused, thus preventing complications from arising from aesthetic or reconstructive surgery that requires the placement of a breast implant.

Question 17

The importance of pec major in reconstructive breast surgery:

Answer 17

1. Provides muscle coverage for the implant.
2. ==> decreased risk of exposure of the implant, since the skin and underlying subcutaneous tissues are often thin following mastectomy.
3. • provides additional tissue between implant and skin, thus decreasing palpability of the implant.

Question 18

Often, placement of the implant beneath the muscle causes it to be noticeable when the pec is …?

Answer 18

CONTRACTED.

In these instances, it may be helpful to RELEASE the pec muscle from its INFERIOR and MEDIAL attachments to decrease the incidence of noticeable contractions.

**In addition, with inferior release of the pec muscle, lower positioning of the implant can be achieved, resulting in a more esthetically pleasing appearance.

Question 19

Serratus anterior - DANGER:

Answer 19

Transection of the long thoracic nerve is carefully avoided during an axillary lymph node dissection because its loss results in “winging” as the scapula is released from the chest wall and moves upward and outward.

Question 20

Because the serratus anterior underlies the lateral aspect of the breast, in esthetic surgery, …?

Answer 20

Blunt elevation of the pec major laterally inadvertently elevates a small portion of the serratus muscle.

==> Often the serratus anterior must be elevated sharply to obtain a sufficient muscle layer to provide coverage of the implant.

Question 21

Role of rectus muscle in reconstructive breast surgery:

Answer 21

In attempting to achieve complete coverage with muscle, the rectus fascia must often be elevated to place the implant sufficiently caudal.

**This dense, thick fascia is often intimately adherent to the ribs below it.
Once the fascia is elevated and released, proper positioning and expansion of the implant can proceed.