CP4 - Mammary Gland and Thoracic Wall Handout Notes and lecture notes (FINAL) Flashcards
List mammary gland surface (Topographic) Anatomy Components
- Breast (location: superficial to the pectoralis major and serratus anterior, extends inferior to the clavicular edge, laterally to the edge of the latissimus dorsi, medial to the sternum, and inferiorly to the rectus sheath);
- External surface consists of the pigmented nipple and areolar tissue ( smooth muscle only in areola)
What are tissue types of internal anatomy of the breast. describe them
Tissue types
a. Glandular tissue
- Breast lobules (rounded segments/unit) produce milk transported through the lactiferous duct to the sinus and out through the nipple
- Composed of 12-15 ductal openings into the nipple!
b. Supporting tissue
- Suspensory ligament of Cooper: connective tissue connections between skin and fascia of pectoralis major. (wear and tear causes sagging when older)
- Adipose (most of the tissue) and connective tissue
List the Anotomical structures related to blood supply.
Blood supply (5 arteries, venous drainage follows similar tract). (Fig. 3)
a. Internal mammary artery branches (to intercostals) b. Lateral thoracic artery c. Thoracodorsal artery d. Intercostal artery (perforators) e. Thoracoacromial artery
No valves are present between which 2 veins that are influential in metastases spread of breast cancer
No valves are present between intercostal veins and vertebral veins that are influential in metastases spread of breast cancer
Name important lymphatic structures of the breasts
. Lymphatics (significant in cancer diagnosis) (Fig. 3)
a. Axillary lymph nodes (responsible for majority of lymphatic drainage)
b. Supraclavicular (greater risk of cancer metastases)
c. Internal mammary (parasternal) (cancer may infect one breast and then move to the other breast via internal mammary lymph nodes)
Name Sensory (dermatomal innervations) structures of the breasts
Sensory (dermatomal innervations)
a. Thoracic intercostal nerves from T3-T5
b. Supraclavicular nerves (upper and lateral breast)
c. Lateral cutaneous branch of T4 (nipple)
What are key points about breast cancer?
touch on incidence, how common it is, its mortality, its correlation with age, and survival rates
Breast Cancer
- Incidence of lifetime breast cancer 1:7 women (by age 90)
- Most common visceral cancer in women
- 2nd most common cause of cancer mortality! (Ex. Incidence in US 211,300 cases, mortality 39,800)
- Risk increases with age
- Survival rates are increasing with better diagnostic screening according to earlier stage of diagnosis and better treatments (reduction of 1.5-2.0 % annually)
Name 7 procedures that deal with how breast cancer may be diagnosed.
describe each or state something noteworthy about it.
• Diagnosis of Breast Cancer (screening abnormalities)
- Self examination (manual inspection of all areas of breast, unsure of increase in protection/survival rates)
- Physician performed examination (only can view surface anatomy, looks for dimpling, thickening, skin lesions, and symmetry)
- Mammograms (significant impact on survival rate and diagnosis!) -Mammograms are typically conducted in two views, craniocaudal view (top-down) for medial/lateral viewing and medial-lateral-oblique view parallel to the pectoral muscle. These views are evaluated together for symmetry and to distinguish microcalcifications from tissue overlap. Not every mass is a cancer. (light areas are electron dense)
- Ultrasound (distinguishes cyst (fluid-filled) vs. solid mass which appears dark on image and determines abscess or not)
- Ductography (radiographic dye fails to envelop papillomas)
- Breast MRI (used to evaluate how extensive the cancer is)
- Needle biopsy (biopsy is the removal of tissue for microscopic inspection)
What is a clinically importanat structure in breast CA
• The axillary tail is clinically important (present in both males and females).
How does glandular and fat tissue vary per breast?
• The size/amount of glandular tissue does not vary per breast, just the amount of fat per mammary gland.
What divides the breasts into compartments?
• The breast is supported and divided into compartments by suspensory ligaments (of Cooper), running from the deep pectoral fascia to the skin.
-suspensory ligaments of cooper Compartmentalize between connective and glandular tissue septae.
How can a tumor in the breasts make the skin look? why does this happen?
• If there’s a tumor (benign or cancerous) in the breast, it can cause dimpling on skin, because the tumor shortens the suspensory ligaments.
Why is lymphatic drainage from breasts clinically important in breast CA?
• Lymphatic drainage from breast is important clinically: 75% drains laterally to axillary lymph nodes, 25% drains inferiorly to abdominal and medially to parasternal lymph nodes
When breast CA appears in one breast and later in the other, what is the likely cause of the second?
why and how does this happen?
• When breast cancer appears on one breast and then on the other breast, it’s unlikely that the two developed independently. More likely the breast cancer metastasized via parasternal lymph nodes through the pectoral major fascia, to the contra lateral breast, where a new tumor grew.
What is the thorax and what does it contain?
The thorax is the region between the neck and abdomen. It is an irregularly shaped space made of bones and muscles and contains components of virtually all eleven systems of the body. However, the majority of the structures found in this region belong to the cardiovascular and respiratory systems. Important structures of the digestive and lymphatic system are also prominent in this region.
- Also an area of transit for some structures
What does the throrax form?
What is it bounded by?
The thorax forms the upper trunk and is bounded by the superior thoracic aperture (anterior wall formed by superior border of manubrium, posterior wall formed by T1) and the inferior thoracic aperture (anterior wall formed by xiphisternal joint, posterior wall formed by T12).
What can the thorax be subdivided into?
The thorax can be subdivided into three compartments: a right lateral, left lateral, and a central compartment.
Describe the lateral compartments
• Lateral thoracic compartments: The right and left lateral compartments consist of their respective pleural sac and lungs. The right side is wider and shorter than the left. This is due to the liver pushing up on the right side and/or the heart pushing down on the left.
What does the central compartment consist of?
• Central compartment consists of the mediastinum and its contents
Name and describe the bones of the anterior thoracic wall
- Clavicle is subcutaneous, it can be felt along its length, just under the skin
- Sternum is the large breastbone in midline. Consists of the manubrium, body, and xiphoid (which means spear-like in Greek)
- Ribs (means “roof over”) help to give shape to the cavity of the thorax.
o The first 7 ribs are attached to the sternum by their own costal cartilage o Ribs 8-10 don’t attach to the sternum directly by costal cartilage, but instead to the costal cartilage of the rib above, helping to create the costal margin of the thoracic cavity o Ribs 11-12 are floating ribs and don’t have any anterior attachment to sternum – are anchored by abdominal wall muscles
Names the bones of the posterior thoracic wall
Bones of the Posterior Thoracic Wall (Fig. 4)
- Scapula is the major bone associated with the thorax, but it’s more important for muscle attachment in the upper limbs (to be covered later)
- Vertebrae were reviewed in an earlier class. They’re important structures as landmarks for the thorax.
What provides resilience to the ribs?
• Costal cartilages provide resilience to ribs
What is noteworthy about ribs in children? Why is this important clinically?
• Because of elasticity of cartilages in children, compression may cause injury to organs, yet ribs will not be broken
What is clinically important about the ribs in old age?
• In old age, costal cartilages may undergo progressive ossification, becoming radio-opaque and give rise to some confusion in chest films
What is clinically important about the first rib?
• 1st Rib: Least likely to be damaged; broad and flat, protected by clavicle
What is clinically important about ribs 2-7
• Ribs 2-7: Most likely to be broken (usually fractured), just anterior to angle of the rib
What is flail chest?
• Flail chest: multiple rib fractures, paradoxical movement of ribs during breathing
What is clinically important about the sternum with regards to rib fractures?
• Sternum is rarely cracked; because of its easy access, most common site for bone marrow extraction
The muscles of the thorax can be subdivided into:
the extrinsic and intrinsic muscles.
For the most part, the extrinsic muscles include the following anterior muscles :
pectoralis major, pectoralis minor, serratus anterior
For the most part, the extrinsic muscles include the following posterior muscles:
trapezius, rhomboids (Major and minor), latissimus dorsi,
-from lecture: levator scapulae, Posterio Superior serratus
the extrinsic muscles have to do with movement of:
upper limbs.
the intrinsic muscles are responsible for :
How are they arranged?
moving the ribs during respiration (although the extrinsic muscles can also function in this capacity, their principal action remains movement of the upper limb) and are arranged in layers.
Name and describe the 4 intrinsic muscles
Intrinsic Muscles (Fig. 5)
1) External intercostals
• Muscles fibers oriented as if putting hands in pockets. They go from superior-lateral to inferior-medial in an oblique fashion.
• Elevate ribs (when the 1st rib is fixed), e.g. they help expand the chest during inhalation
- end at mid-clavicular line, but continues as a membrane all the way to the sternum
2) Internal intercostals
• Muscle fibers are arranged perpendicular to the external intercostals.
• depress ribs during expiration, e.g. they help forcefully exhale air
- attaches to sternum and becomes a membra in the back (reverse of external intercostals)
3) Innermost intercostals
• “Probably elevate the ribs.”
4) Transversus thoracis muscles
• Depress the ribs in midline, as well as help attach vessels/veins to sternum.
What is clinically important about the intercostal muscles?
• Intercostals are not completely continuous anteriorly and posteriorly; membranous layers help to complete the spaces left unfilled by the muscles.
