Download anterior chest wall and breast anatomy

ANTERIOR CHEST WALL AND BREAST ANATOMY
Landmarks of surface anatomy
Closed tube thoracostomy
- Done on the 5th ICS mid axillary line
>> Treatment of thoracic trauma with complications of pneumothorax (air or gas in the pleural cavity) and hemothorax (blood in the pleural cavity)
not requiring open surgical intervention is with closed tube thoracostomy. The tube is introduced through a small incision.
Precordial area
AUDIO
>> All patients suffering a penetrating injury in cardiac proximity should be considered at risk for a cardiac wound. Cardiac proximity is an area
bounded superiorly by the clavicles, inferiorly by the costal margin and laterally by the midclavicular lines (“cardiac box”).
Muscles of the anterior chest wall
Pectoralis major
o the sternal part of the sternocostal head of the pectoralis major originates from the manubrium and body of the sternum
o the clavicular fibersof the pectoralis major originates from the medial half of the anterior surface of the clavicle
o 2 heads of the pectoralis major originates from the medial half of the anterior surface of the clavicle
o Anterior axillary fold is formed by the inferior border of the pectoralis major muscle
o thick fan-shaped muscle
o arises from the anterior surface of the sternal half of the clavicle
o Converges to a flat tendon which is attached to the lateral lip of the intertuberous sulcus of the humerus
o tendon is bilaminar (2 thin layers)
o anterior lamina is formed by fibers from the manubrium, which are joined superficially by clavicular fibers and deeply by
fibers from the sterna margin and the 2nd to 5th costal cartilages
o posterior lamina receives fibers from the 6th costal cartilages,6th rib, sternum and aponeurosis of the external oblique
o Blood supply
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pectoral branch of the thoracoacromial axis
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perforating branches of the internal thoracic arteries and superior and lateral thoracic arteries
o Innervation
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Lateral and medial pectoral nerves
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Fibers for the clavicular part are from C5 and C6, for the sternocostal part from C6, C7, C8, T1
o Action
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Adduction and medial rotation of the humerus against resistance
Pectoralis minor
o Triangular muscle lying posterior to the pectoralis major
o Extends from the upper margins and outer surfaces of the 3rd-5th ribs near their cartilages and from the fascia over the
adjoining external intercostals muscles
o Its fibers ascend laterally under the pectoralis major converging on a flat tendon which is attached to the medial border
and upper surface of the coracoids process of the scapula
o Blood supply
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Pectoral and deltoid branches of the thoracoacromial and superior and lateral thoracic arteries
o Innervation
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branches of medial and lateral pectoral nerves
o Action
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Assists serratus anterior in drawing scapula forward around the chest wall
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With the levator scapulae and rhomboids it rotates the scapula depressing the point of the shoulder
o Both pectoralis muscles are quiescent during inspiration but active in forced inspiration
o Deltopectoral triangle
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Bounded superiorly by the clavicle, laterally by the deltoid muscle, medially by the pectoralis major muscle
o Cutaneous innervation of the pectoral region
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Supraclavicular nerves (C3, C4)
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Upper thoracic nerves (T2-T6)
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Brachial plexus (C5, C6, C7, C8, T1) does not supply cutaneous branches to the pectoral region
Subclavius
o Muscle between clavicle and 1st rib
o Arises from the junction of the 1st rib and its costal cartilage by a thick tendon
o Passes upwards and laterally to a groove on the under surface of the middle 1/3 of the clavicle
o Posteriorly, it is separated from the 1st rib by the subclavian vessels and the brachial plexus
o Anteriorly, it is separated from the pectoralis major by the anterior lamina of the clavipectoral fascia
o Blood supply
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clavicular branch of thoracoacromial artery and suprascapular artery
o Innervation
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subclavian branch of the brachial plexus, which contains fibers from C5 and C6
o Action
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pulls the point of the shoulder down and forward and braces the clavicle against the articular disc of the
sternoclavicular joint
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protects the subclavian vessels in fractures of the clavicle which rarely involve these vessels
Muscle layers of the intercostal space
External intercostal muscles
o 11 pairs extend from tubercles of the ribs where they blend with the posterior fibers of the superior costotransverse
ligaments and continue forward to the sternum as an aponeurotic layer called the external intercostal membrane
o
each muscle passes from the lower border of one rib to the upper border of the rib below
o
Innervation
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innervated by the adjacent intercostals nerve
o Action
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acts with the internal intercostals
Internal intercostals
o 11 pairs of internal intercostals begin anteriorly at the sternum, in the interspaces between the cartilages of the ribs and at
the anterior extremities of the cartilages of the false ribs
o continue as far back as the posterior costal angles where each is replaced by an aponeurotic layer called the internal
intercostals membrane
o each muscle descends from the floor of a costal groove and adjacent costal cartilage and inserts into the upper border of
the rib below
o the fibers are at the right angles to those of the external intercostals muscles
o
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Innervation
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Innervated by the adjacent intercostals nerve
o Action
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act with the external intercostals
o Internal: expiration
o External: inspiration
Innermost intercostals
o each muscle is attached to the internal aspect of 2 adjoining ribs
o posteriorly they may come together with the corresponding subcostals
o innermost intercostals are related internally to the endothoracic fascia and parietal pleura and externally to the
intercostals nerves and vessels
o innervation
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supplied by the adjacent intercostals nerve
o action
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acts with the internal intercostals
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Subcostales
o muscular and aponeurotic fascicule
o well developed in the lower part of the thorax
o each descends from the internal surface of one rib near its angle to the inter surface of the 2nd or 3rd rib below
o fibers run parallel to the internal intercostals and lie between the intercostals vessels, nerves and pleura
o Innervation
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innervated by the adjacent intercostals nerves
o action
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each depresses the ribs
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Transversus thoracis
o also called triangularis sternae and sternocostalis
o spreads over internal surface of the anterior thoracic wall
o arises from the lower 1/3 of the posterior surface of the sternum, the xiphoid and the costal cartilages of the lower true
ribs near their sternal ends
o fibers diverge and ascend laterally as slips that pass into the lower borders and inner surfaces of the costal cartilages of the
2nd , 3rd , 4th , 5th and 6th ribs
o the lowest fibers are horizontal and contiguous with highest fibers of the transversus abdominis and the highest fibers are
almost vertical
o
o
o
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it separates the intercostals nerve from the pleura
innervation
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adjacent intercostals nerve
action
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pulls down costal cartilages to which it is attached
Levatores costarum
o strong bundles, 12 each on each side, that arise from the tips of the transverse processes of the 7th cervical and 1st to
11th thoracic vertebrae
o they pass obliquely downwards and laterally parallel with the posterior borders of the external intercostals
o each is attached to the upper edge and external surface of the rib immediately below the vertebra from which it takes its
origin, between the tubercle and angle
o each of the 4 lower muscles divides into 2 fasciculi
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one is attached as described and the other descends to the 2nd rib below its origin
o Innervation
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innervated by the lateral branch of the dorsal rami of the corresponding thoracic spinal nerves
o Action
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elevate ribs but their importance in ventilation is disputed
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act from their costal attachments as rotators and lateral flexors of the vertebral column
Serratus anterior
o spans from the superior 9 ribs in the mid clavicular line to the medial border of the scapula
o the fibers converge from the 4th‐9th ribs converge on the interior angle of the scapula
o Innervation
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innervated by the long thoracic nerve (injury to this nerve causes winging of the scapula)
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SKELETON
the skeleton of the thorax consists of the 12 thoracic vertebrae, 12 pairs of the ribs and costal cartilages and sternum
Anteriorly, the superior 7 costal cartilages articulate with the sternum
8th, 9th and 10th cartilages articulate with cartilage above
11th and 12th are “floating ribs”, their cartilages do not articulate anteriorly
clavicle lies over the anterosuperior surface of first rib, making it difficult to palpate
Thoracotomy
open the chest on the 5th intercostals space
each ribs articulates posteriorly with the vertebral column
posteriorly, all ribs incline inferiorly
anteriorly, the 3rd to 10th costal cartilage incline superiorly
the scapula is suspended from the clavicle and crosses the 2nd to the 7th ribs
the trachea can be palpated through the jugular notch or suprasternal notch
the sternal angle or junction between the manubrium and the body is a palpable landmark guiding your fingers to the 2nd costal cartilage
the xiphoid process is palpable on the inferior edge of the body and forceful displacement can cause injury to the liver
7 costal cartilages articulate with the sternum
o 1st with the manubrium
o all others with the body of the sternum
Pericardiocentesis
procedure where fluid is aspirated from the Pericardium
the internal mammary vessels run laterally to the edge of the sternum providing intercostals branches
o internal mammary artery harvested and used as a graft un a coronary artery bypass
internal mammary lymph nodes drain the intercostal spaces, the costal pleura and medial part of the breast
it is by this route that breast cancer may spread to the lungs and mediastinum
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IV. Breast Anatomy
the breast extends from the 2nd to the 6th rib and the axillary tail projects into the axilla
transversely, it extends from the lateral border of the sternum to the anterior axillary or midaxillary line
the axillary tail of Spence extends superolaterally into the anterior axillary fold
>> A small part of the mammary gland may extend along the inferolateral edge of the pectoralis major toward the axilla, forming an axillary
tail (of Spence). Some women discover this when it enlarges during menstruation. This portion of breast tissue is in the upper-outer quadrant
of the breast. 50% of breast cancer is located in this quadrant and in the axillary tail.
15‐20 lobules enter into branching and interconnected ducts
ducts widen beneath the nipple as lactiferous sinuses then empty as 5‐9 nipple openings
suspensory ligaments extends from the glandular tissues to the deeper layers of the skin
breast cancer can cause fibrosis of the suspensory ligaments which will cause skin retraction
this does not represent a grave sign, it does not mean there is direct skin involvement
A. Lymphatic Drainage of the Breast
Drains into internal mammary nodes
the whole breast drains into the nipple  Sappey’s subareolar plexus  dermal lymphatic  and the breast is drained to the 1‐3 sentinel
nodes
Lymphatics drain primarily through the breast into Sappey's subareolar plexus which communicates with the dermal lymphatics with the
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breast
>>For a picture and a more detailed discussion of the lymph drainage of the breast  http://196.33.159.102/1951%20VOL%20XXV%20JanJun/Articles/05%20May/4.5%20LYMPH%20DRAINAGE%20%20OF%20THE%20BREAST.%20Dr.%20R.%20Singer.pdf
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Sentinel Lymph Node Biopsy
inject a blue dye into the breast where cancer is or underneath the nipple
this will tell you whether all lymph nodes have to removed or only the sentinel
aside from sentinel dye, a radioactive material is injected and a gamma probe is used to probe and the point where it is very noisy that is
where the sentinel node is and that is where you cut.
V. Breast Cancer
A. Stages of Breast Cancer
Stage 1 – the cancer has not spread to lymph nodes
 TINOMO
Stage 2 – spread to axillary lymph nodes
 T0N1M0, T1N1M0, T2N2M0
Stage 3 – bigger tumors and nodes positive in axilla
 Stage 3B (T4- skin involvement)
 Stage 3C (nodes palpable in the supra
Stage 4 – goes to lungs and liver (metastasis)
B. Treatment Options
Aim of breast surgery is to:
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Remove the breast cancer from the breast
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Test whether the breast cancer cells have spread to the lymph nodes in the armpit
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Breast Conserving Surgery
Surgery to remove the Breast Cancer and a small margin of healthy tissue around it and remove the lymph nodes in the axilla
Radiotherapy after surgery
Lumpectomy (excision of the cancer with a margin of normal tissue) + ALND (axillary lymph node dissection) + radiotherapy
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Usually done for early Breast Cancer (stage I and II)
Can be done for locally advanced Breast cancer (stage III) if responsive to chemotherapy
Size of the tumor is no longer the criteria for BCT. More of tumor size to breast volume ration
Recurrence rate is 1% per year or 10% in 10 years
Mastectomy/Modified Radical Mastectomy (MRM)
Surgery to remove the whole breast and the lymph nodes in the axilla
Remove the whole breast but preserve pectoralis major and minor muscles + ALND
Recurrence rate is <1% since no breast tissue left
Survival rates from MRM or BCT is the same
B. Blood Supply to the Breast:
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The breast receives its principal blood supply from:
o Perforating branches of the internal mammary artery
o Lateral branches of the posterior intercostals arteries
o Branches from the axillary artery
o The veins of the breast follow the course of the arteries
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Batson’s plexus
o Vertebral venous tributaries
o Provides a secondary route from metastases of breast cancer
o Invests the vertebrae and extends from the base of the skull to the sacrum
o Venous channels exist between this plexus and the veins associated with the thoracic, abdominal, and pelvic organs
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These potential pathways explain metastases to the vertebrae, skull, pelvic bones and the CNS in the absence of pulmonary
metastases
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C. Innervation of the Breast
Nerves of the breast are principally derived from the 4th, 5th and 6th intercostals nerves
Area of the skin on the upper portion of the breast is supplied by the anterior or medial branches of the supraclavicular nerve
Lateral branches of the intercostal nerves supply the anterolateral thoracic wall
The 3rd to 6th branches (lateral mammary branches) supply the breast.
Spectrum of changes leading to the development of invasive ductal cancer:
C. Breast Diagnostics/Diagnostic Modalities
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1) Mammography
Only diagnostic tool which can detect breast cancer even before it can be felt
Screening mammography is associated with 20‐ 30% fewer deaths from breast cancer in women aged 40‐69 years old
Most women < 40yrs old have dense breast meaning they have more glandular tissue than fatty tissue in their breast
o Their mammograms are mostly white and it is difficult to detect any lesion
Breast implants DO NOT cause breast cancer BUT their presence makes it difficult to detect cancer
Mammography on breasts with implants requires special positioning and expertise in interpretation
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2) Ultrasound
Breast ultrasound is done to:
 Evaluate a breast lump found on SBE, physical exam or mammography
 Determine whether lump is solid or cystic
 Evaluate breast of younger women
 Guide the placement of a needle or other instruments during a breast biopsy or breast surgery
 Monitor the growth of a cyst or guide the placement of a needle to drain the cyst
 Evaluate breast with silicone implants
 Evaluate breast symptoms, such as pain, redness, and fever
 Evaluate pregnant women with masses
 Evaluate women with fibrocystic breast disease
Better diagnostic tool for women less than 40 years old
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3) MRI
Has proven to be a very good diagnostic tool for imaging breast with implants
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D. Breast Cancer Risk Factors
To be a woman is to be at risk for breast cancer
There is NO known cause of breast cancer
AGE – biggest single risk factor
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History of previous breast cancer, ovarian cancer or uterine cancer
First menstruation before 12 years old or menopause after 55 years old
NO pregnancy, NO breastfeeding, first pregnancy after 30 years old
Hormone replacement therapy/ oral contraceptive pills
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can cause cancer when oral contraceptive pills are taken in continuously
Radiation exposure (radiotherapy)
1st degree relative with Breast cancer
o
only 10% of all breast cancer is hereditary
overweight/obese women
high alcohol intake
What is within your control?
Weight control
Balanced diet
Exercise
Decrease alcohol use
Avoid prolonged use of oral contraceptive
E. How to screen for Breast Cancer
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1) Self Breast Exam
Start at 20 years old
Do it one week after menstruation (after the 1st day)
Menopausal women, do it at the same time every month
Step 1: Look at your breast
Step 2: look at your breast with arms raised
- Check:
o Symmetry
o Size
o Shape
o Color
o Distortion
Step 3: While lying down, feel your breast in a circular motion moving towards the nipple
Using 3 fingers you palpate radial, circular, up and down (what is important is to cover the whole breast)
Deep palpation – you must feel the chest wall
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Step 4: Repeat step 3 (in the shower) while standing then squeeze nipple to check for discharge
Look for:
o New lump
o Unusual thickening
o Sticky or bloody nipple discharge
o Skin changes such as puckering/dimpling
o Unusual increase in size of one breast
o One breast unusually lower than the other
2) Check‐ups with your doctor
Starting at 35 years old and older
3) Annual Mammography
Starts at 50 years old, once a year until 70 years old and at 10 years before age of diagnosis of family member with history of breast
cancer
Lumps that cannot be felt CAN be detected by mammography