Lecture 3 - Mammary Gland and Thoracic Wall (GA) Flashcards
Definition of the thorax?
Area between neck and abdomen
What are the mammary glands part of?
Superficial fascia
What do breasts primarily consist of?
Fat
Where is the breast located?
- Deep to dermis
- Superficial to deep fascia superficial to the pectoralis major and serratus anterior
- Inferior to clavicular edge
- Superior to rectus sheath
- Lateral to the edge of the latissisimus dorsi
- Medial to the sternum
What gives shape to the breasts? Describe their location
The suspensory ligaments of Cooper
Extend perpendicularly from the deep fascia superficial to the pectoralis major to the skin
Does the amount of milk produced by breasts vary with their size? Why/Why not?
NOPE because the amount of glandular tissue does not vary with size
Describe the pathway of milk in the breast.
Breast lobules produce milk => lactiferous ducts => lactiferous sinus => 12-15 ductal openings into the nipple
Are lactiferous ducts found in all women?
NOPE, they disappear after menopause because they depend on hormones
Do both male and females have an axillary breast tail?
YUP
What does the external surface of the breasts consist of?
- Pigmented nipple
2. Areolar tissue with glands
Role of areolar glands?
Sebaceous glands that enlarge during pregnancy to help lubricate the skin for breast feeding
When do the nipple and areola become more pigmented? How come? In which population is this exacerbated?
During the last trimester of the 1st pregnancy
Due to increased amount of melanin
In African Americans
Where is the ONLY muscle of the mammary gland located? What kind? When does it contract?
The areola - smooth muscle
Contracts upon stimulation
What are the 5 arteries providing blood supply to the breasts?
- Internal thoracic artery branches (to intercostals)
- Lateral thoracic artery branches
- Thoracodorsal artery
- Intercostal artery (perforators)
- Thoracoacromial artery
What is another name for the internal thoracic artery in females?
Internal mammary artery
Is the breast affected by coronary bypass surgery in females in which the internal thoracic artery is harvested? Why/Why not?
NOPE, because of the extensive and redundant blood supply of the breast
What are the 2 tissue types of the breast?
- Glandular tissue
2. Supportive tissue
What are the 3 types of supportive tissue of the breast?
- Suspensory ligaments
- Fat
- Connective tissue
Describe the venous drainage of breasts.
Follows the same tracts as the arteries
What are the 4 types of lymph nodes that drain the breast? Which one is responsible for the majority of the lymphatic drainage?
- Axillary lymph nodes*** (75% of drainage)
- Supraclavicular lymph nodes
- Internal mammary lymph nodes
- Abdominal lymph nodes (25% of drainage)
What is another name for internal mammary lymph nodes?
Parasternal lymph nodes
Which breast lymph nodes are at greater risk for cancer metastases?
Supraclavicular lymph nodes
How can breast cancer move from one breast to the other?
Via internal mammary lymph nodes through the pectoral major fascia
What artery does the lateral thoracic artery branch from?
Axillary artery
What artery does the internal thoracic artery branch from?
Subclavian artery
Why can cancer spread easily from the breasts to the vertebral column/brain?
Because there are no valves between the intercostal veins and the vertebral veins
How do surgeons divide breasts?
4 quadrants
Where do most breast cancers occur? In what lymph nodes do these drain?
Superior lateral quadrants
Drain into axillary lymph nodes
Can surgery alone potentially cure breast cancer?
If caught early enough, yes
What are 5 explanations for felt breast lumps? List in order of %
- Fibrocystic changes
- No disease
- Miscellaneous benign
- Cancer
- Fibroadenoma
Incidence of lifetime breast cancer in women?
1:7 by age 90
Is breast cancer the most common visceral cancer in women?
YUP
Does breast cancer risk increase with age?
YUP
What are the 7 breast cancer screening techniques? Which one is the gold standard for significantly impacting survival rates?
- Self examination
- Physician performed examination
- Mammogram***
- Ultrasound
- Ductography
- MRI
- Needle biopsy
When does breast examination indicate breast cancer? Explain each symptom.
- Skin dimpling because the cancer cells are attacking the suspensory ligaments of Cooper and shortening them
- Prominent vascular patterns because a fast-growing tumor will have a large vascular demand and will cause dilation of superficial veins
- Skin edema due to lymph accumulation in the skin (orange peel appearance) because the cancer is attacking the subcutaneous lymphatics
- Nipple retraction due to shortening of lactiferous ducts
Does breast self-examination increase breast cancer survival rates?
Unsure
What are the 2 views that mammograms are conducted in?
- Craniocaudal view
2. Medial-lateral oblique view
What are breasts ultrasounds used for?
To distinguish fluid-filled cysts (light) from solid masses (dark)
What are breasts MRI used for?
To evaluate how extensive the breast cancer is
How is breast examination conducted?
- Breast is palpated systematically either in concentric circles or by quadrant
- Flat parts of the fingers are used to press down to reveal masses
- Nipple is squeezed to detect bleeding or discharge
What are breast fibrocystic changes due to?
Usually due to menstrual cycle
What is fibroadenoma?
Benign neoplasm of glandular epithelium with significant increase in connective tissue
What color would a breast tumor appear as on a mammogram?
White
What is the purpose of a needle biopsy to detect breast cancer?
Usually done after a mammogram has identified a tumor - done to assess whether it is cancerous or not
What are the next steps once breast cancer has been identified via the biopsy?
- Masectomy OR lumpectomy to remove the tumor with incisions above and below the nipple parallel to the Langer lines to minimize scarring
- Removal and biopsy of axillary lymph nodes with or without axillary incision (depending on whether masectomy or lumpectomy was performed) to test for metastasis
- Surgical repair after radical masectomy
Which 2 nerves are very important to preserve during a masectomy?
- Long thoracic nerve, which controls serratus anterior
2. Thoracodorsal nerve which controls latissimus dorsa
How do surgeons performing masectomies or lumpectomies find the lymph nodes to remove?
Lymph mapping using an injection of dye in the breast where the tumor was which will travel to the proximal lymph nodes to the tumor
What cancer is the second most common cause of mortality in women?
Breast cancer
Can a benign tumor cause dimpling of the breast?
YUP
What are the 2 methods of surgical repair following a radical masectomy? Explain each. Which works best?
- Transverse rectus abdominus myocutaneous (TRAM) flap surgery***: opposite rectus adbominus muscle is used to replace the mass lost and retains blood supply because it had both a superior and an inferior one
- Latissimum dorsi flap
What is a radical masectomy?
Masectomy involving the removal of the pectoralis major and minor due to metastasis
How is the nipple surgically repaired after radical masectomy?
CV flap or double opposing tab techniques + tattooing
What are the 3 functions of the thorax?
- Protection of vital organs
- Breathing
- Conduit
What are the 3 bones of the anterior thoracic wall?
- Clavicle
- Sternum
- 12 ribs
What are the 3 regions of the sternum?
- Manubrium
- Body
- Xiphoid
Are the scapula and clavicle subcutaneous?
YUP
What is the superior inlet of the thoracic made of? What is it called?
Superior thoracic aperture:
- Anterior wall = superior border of manubrium
- Posterior wall = T1
- Laterally = rib 1
What is the inferior inlet of the thoracic made of? What is it called?
Inferior thoracic aperture:
- Posteriorly: T12
- Posterolaterally: rib 12 and the distal end of rib 11
- Anterodistally: cartilaginous ends of ribs 7 to 10 (costal margin)
- Anteriorly: xyphoid process
What are the 3 compartments of the thorax? What does each consist of?
- Right and left lateral compartment: pleural sacs and their respective lung
- Central compartment: mediastinum and its contents
Are the right and left lateral thoracic compartments identical?
NOPE, the right side is wider and shorter than the left because of the liver pushing up on the right side and/or the heart pushing down on the left
How many ribs do humans have?
12
Describe the articulations of the ribs.
- Ribs 1-7 attach to the sternum by their own costal cartilage
- Ribs 8-10 attach to the sternum by the costal cartilage of the above rib
- Ribs 11-12 are floating and do not attach to the sternum
How are rib 11 and 12 anchored to the thoracic wall?
By abdominal wall muscles
What forms the costal margin of the thorax?
Distal cartilaginous ends of ribs 7 to 10
What are the 2 bones of the posterior thoracic wall?
- Scapula
2. 12 vertebrae
What allows the ribs to be highly mobile and be very resilient?
Their costal cartilage
Which ribs are typical?
3 to 10
What is the purpose of the costal groove of ribs?
Protects nerves, arteries, and veins that travel under the ribs
Which ribs are atypical?
1, 2, 11, and 12
How are the first 2 ribs different?
More curved and thicker
What membrane covers the ribs?
Periosteum
What can the mobility of the ribs be exploited for?
To access the thoracic cavity during thoracotomy
What does the suffix “-otomy” mean?
Surgery to enter a certain body space
What does the suffix “-ectomy” mean?
Removal of a body structure
What kind of patients have more elastic rib costal cartilage? What is a consequence of this?
Children
Compression may cause injury to the organs without fracturing the ribs
Which rib is the least likely to be fractured? Why?
1 because it is broad and flat and protected by the clavicle
Which ribs are most likely to be fractured?
2-7
What is a flail chest?
Acute condition in which multiple rib fractures (multiple fractures per rib and multiple ribs affected on both sides of the chest) cause paradoxical movement of ribs during breathing: broken rib goes inward during inspiration
What can happen to the ribs with old age? Consequence of this?
Ossification of costal cartilages which become radio-opaque and cause confusion in chest films (looks like cancer) and loss of rib resiliency
What can be a complication of flail chest? Explain.
Broken rib punctures the lining of the lung pleura: pneumothorax
How long after pneuomothorax can you live for?
30 min
What bone is a common site for bone marrow extract?
Sternum
Is the sternum often fractured? Why/Why not?
NOPE because of resiliency of costal cartilages
What is a potential complication of sternum fracture?
Heart injury
What is the rate of mortality of sternal fractures?
25-45%
What are the 2 types of thoracic muscles?
- Intrinsic
2. Extrinsic
Function of intrinsic muscles?
Moving ribs during respiration
Can the extrinsic muscles be used for breathing?
YUP, but not main action
Function of extrinsic muscles?
Moving upper limbs
How are intrinsic thoracic muscles arranged?
In layers
What are the 3 anterior extrinsic thoracic muscles?
- Pectoralis major
- Pectoralis minor
- Serratus anterior
What are the 6 posterior extrinsic thoracic muscles?
- Trapezius
- Rhomboid major
- Rhomboid minor
- Latissimus dorsi
- Levator scapulae
- Posterior superior serratus
What are the 4 types of intrinsic thoracic muscles? List from superficial to deep
- External intercostals
- Internal intercostals
- Innermost intercostals
- Transversus thoracis muscles (same plane as innermost intercostals)
Describe the orientation of external intercostal muscles.
From superior lateral to inferior medial (until reaching the external intercostal membrane) in an oblique manner
Function of external intercostal muscles? How?
Elevate ribs during inhalation
First rib is fixed by scalene muscles that anchor it to the bones of the neck
Describe the orientation of internal intercostal muscles.
Perpendicular to the external intercostals
Function of internal intercostal muscles? How?
Depress ribs during forceful expiration
12th rib is fixed by the quadratus lumborum to the vertebrae
Are intercostal muscles continuous around the chest?
NOPE, membranous layers help complete the spaces left unfilled by the muscles
Where do the nerves and vessels (artery + vein) of the intrinsic thoracic muscles travel? How are they arranged? What is the clinical significance of this?
Between the internal and innermost intercostal muscles underneath each rib
Superior to inferior: V, A, N
During a pleural tap, the needle is inserted on the upper border of the rib so as to minimize potential damage to nerves
Function of innermost intercostal muscles?
Probably elevate the ribs
Function of transversus thoracis muscles?
Depress the ribs in midline + help attach vessels/veins to sternum
What is a pleural tap?
Bore needle is introduced into the pleural cavity to drain fluid/blood
What is the collateral branch of the intercostal vein, artery, and nerve?
Much smaller branches located above each rib
What are the 3 diameters of the thoracic cavity? What is each changed by? How is each increased during inspiration?
- Vertical: diaphragm moves inferiorly and pushes down on abdominal organs
- Antero-posterior: fixed 1st rib - external intercostals as chest moves outward
- Transverse: fixed 1st rib - external intercostals: bucket handle arrangement
How does inspiration occur?
Size of thoracic cavity is increased and air rushes inside the lungs
What is the most important structure of respiration?
Diaphragm
What are the 2 types of breathing? 2 names for each
- Quiet inspiration = eupnea
2. Forced breathing = hypernea
Describe eupnea.
- Inspiration by muscular contraction: diaphragm (deep breathing) or costal (shallow breathing) with external and innermost intercostals
- Expiration is a passive process without muscle contraction
How is the breathing affected during pregnancy?
Women increasingly rely on costal breathing because the uterus enlarges and pushes against the abdominal viscera and vertical thoracic diameter cannot be increased
Describe hypernea.
Active inspiratory and expiratory movements:
- Inspiration: diaphragm (deep breathing) or costal (shallow breathing)
- Expiration: transversus thoracic, internal intercostals, and abdominal muscles
What are the 6 surface projections of the thorax?
- Suprasternal notch: projects posteriorly to T2/T3
- Sternal angle: see other flashcard
- Sternum: anterior to heart
- Xiphisternal joint: projects posteriorly to T9
- Nipple in males: 4th intercostal space
- Apex beat of the heart: 5th intercostal space, 3.5 inches from midline on the left (or 1-2 inches below nipple)
What does the sternal angle plane separate?
- Superior and inferior mediastinum
- Trachia branching out into bronchi
- Boundaries of the aortic arch
- Vertebral level between T4 and T5
- Second rib joins sternum
- Azygos vein drains to IVC
- Manubrium and body of sternum join
- Uppermost level of the pericardium
- Superior limit of pulmonary trunk
Other name for sternal angle?
Angle of Louis
Where do you listen for the heartbeat during a physical?
The apex beat of the heart
Where do you pump during CPR?
Over the sternum
What is a bore needle?
Needle wth a large hole in its centre
Which are true ribs? Which are false?
True: 1-7
False: 8-12
Which ribs are NOT mobile?
Ribs 11 and 12
