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99 terms

Bony thorax - sternum and ribs - Ch 11

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bony thorax function
to serve as an expandable bellowslike chamber
protects organs of resp. sys and heart and great vessels
bony thorax consists of
sternum
thoracic vertebrae posteriorly
12 pairs of ribs
site for marrow biopsy
the sternum - local anesthesia is inserted into marrow cavity to get a sample of the rbm
sternum parts
manubrium
body
xiphoid process
manubrium
upper portion of sternum - 2 inches avg
body of sternum
longest part of sternum
4"
union is not complete until age 25
xiphoid process
most inferior part of sternum
cartilage during infancy and youth
doesn't ossify until age 40
small but can vary in size, shape and degree of ossification
jugular notch
uppermost border of the manubrium
T2-T3
other names for the jugular notch
suprasternal or manubrial notch - b/w clavicles and manubrium
sternal angle
where the lower end of manubrium joins the body - palpable
T4-T5
xiphoid process
T9-T10
inferior costal angle (rib)
L2-L3
sternoclavicular articulation
clavicle and manubrium articulation
only bony connection b/w each shoulder girdle and the bony thorax
how many pairs of ribs join the sternum
7 - union is cartilage
facet
articulation with cartilage of ribs
costocartilage
term for short piece of cartilage that connects anterior ribs to sternum
2nd costocartilage connects at the level of the
sternal angle
Ribs 8, 9, and 10
have costocartilage, but connect to the number 7 costocartilage instead of directly to the sternum
First 7 pairs of ribs
true ribs - because they connect directly to the sternum
false ribs
last 5 pairs of ribs
floating ribs
false ribs 11 and 12 - do not possess costocartilage and do not connect to the 7th rib's costocartilage
two ends of the ribs
sternal end
vertebral end
between the 2 ends of the rib
shaft or body of the rib
vertebral end of rib consists of a
head - articulates with 1-2 thoracic vertebrae
neck - flattened
tubercle - articulates with transverse process of a vertebra, allows attachment for a ligament
angle - forward angulation, and downward
posterior (vertebral) end of a typical rib is
3-5" higher than the anterior (sternal) end
On a radiograph, the most superior part of the rib is
the posterior end or end nearest the vertebrae
lower inside margin of each rib protects an
artery, a vein and a nerve
rib injuries
very painful
associated with substantial hemorrhage
costal groove
inside margin that contains the blood vessels and nerves
first ribs of the rib cage are
short and broad and most vertical
most sharply curved
ribs get
longer and longer down to the 7th rib
From the 7th rib, ribs get
shorter and shorter
bony thorax is widest at the
lateral margins of the 8-9th ribs
costochondral union/junction
b/w the costocartilage and sternal end
synarthrodial - no movement permitted
cartilage and bone are bound by periosteum of the bone itself
sternoclavicular jt
synovial, permit plane/gliding motion
diathrodial
sternocostal jt of rib 1
cartilage of 1st rib and manubrium - no motion - synarthrodial
cartilaginous, synchondrosis
sternocostal jt of rib 2-7
b/w costocartilage and sternum - synovial
plane/gliding - diarthrodial
interchondral jt
b/w costal cartilages of #6-10 ribs - synovial, gliding, diarthrodial - for breathing process
costotransverse jts and costovertebral jts
synovial, gliding, diarthrodial
since sternum is on same plane as spine,
patient needs to be rotated 15-20° RAO
the 15-20° RAO position
shifts the sternum to the left of the thoracic vertebrae and into the homogenous heart shadow
Degree of obliquity required is dependent on the size of the
thoracic cavity
shallow/thin chest - requires MORE rotation to cast sternum away from thoracic spine. - 20°
barrel chest requires 15°
sternum is made of
spongy bone with thin layer of hard, compact bone surrounding it
kVp for sternum
65-70 kVp
breathing technique for sternum
shallow breaths to blur lung markings overlying the sternum
requires 65±5 kVp, low mA and long exposure time of 2-3 seconds
SID for sternum
40"
used to use a lower SID to create magnification of overlying ribs and sternum - increased exposure to pt, so not recommended
skin should be at least
15 inches (38cm) from collimator
patient history should include
nature of complaint - acute vs chronic, how injury occurred
location of rib pain or injury
if injury is caused by trauma to thoracic cavity - does pt have difficulty breathing
Is pt able to stand
ribs above diaphragm
upper 10 posterior ribs
Take radiograph erect if able
suspend on inspiration
low kvp - 65-70 because of lung tissue - lower kVp allows better visualization
If injury is over heart area - higher kVp may be needed to visualize ribs thru heart shadow and lung fields
when erect,
Gravity lowers diaphragm
Allows deeper inspiration
for above the diaphragm, breathing should be
suspended during inspiration
ribs below diaphragm
lower ribs
take recumbent - allows the diaphragm to rise to highest position and results in less thick abdomen (especially on bigger pts, because abdomen flattens when recumbent) Provides better visualization of lower ribs through abdominal structures
Suspend on expiration - allows diaphragm to rise to level of 7th or 8th posterior ribs - providing uniform density for below ribs
when recumbent for lower ribs,
allows the diaphragm to rise to highest position
results in less thick abdomen (especially on bigger pts, because abdomen flattens when recumbent)
for below the diaphragm, breathing should
suspended on expiration
recommended projection
place area of interest closest to IR
rotate spine AWAY from area of interest to prevent superimposition
if left posterior ribs are injured, use a
straight AP and a
LPO - moves spinous processes away from the left side and reduces foreshortening of ribs
if right ANTERIOR ribs are injured, us a
straight PA and a
LAO - moves spinous process away from site of trauma and elongates axillary portion of right ribs
BB marker
ensures radiologist is aware of the location of the trauma or pathology - each tech should determine dept protocol first
trauma to the bony thorax, respiratory system, history or rib injuries may also require
PA chest and
Lateral chest
to rule out pneumothoras, hemothorax, pulmonary contusion or other chest patholgoy
if pt cannot be erect for chest radiographs,
air-fluid levels must be ruled out, and a horizontal beam projection in decub position s/b included
pediatrics
pt motion and safety
immobilization
guardian with lead to hold pt
short exposure time, high mA
breathing technique is not indicated for pediatrics
collimation
Geriatric
fear of falling
radiolucent mattress or pad
blankets
decrease in kV or mAs
tremors require short exposure time, and high mA
digital considerations
correct centering and close collimation
ALARA
EI review may indicate a reduction in mAs is possible for future exposures
CT
provides cross sectionaly images of the bony thorax. Skeletal detail and associated soft tissues - good for evaluating sternum and/or sternoclavicular jts
nuclear med
radionuclide bone scan detects skeletal pathologies of thoracic cage (metastases, occult fx) - radiopharmaceutical-tagged tracer element is injected - and will demo hot spots - increased bone activity - abnormal area is investigated with radiography.
Bone scans are usually common practice for
pts who are at risk or symptomatic for skeletal metastases (except multiple myeloma)
fx
break in the structure of a bone
fx of bony thorax can be
dangerous due to proximity of lungs, heart and great vessels
rib fx
most commonly caused by trauma or underyling pathology
fx of 1st rib
associated with injury to underlying arteries/veins - disruption of bony cortex of rib, linear lucency thru the rib
fx of ribs 8-12
associated with injury to adjacent organs such as the spleen, liver or kidney - disruption of bony cortex of rib, linear lucency thru the rib
any rib fx may cause
injury to the lung or cardiovascular structures (pneumothorax, pulmonary or cardiac contusion)
flail chest
fx of adjacent ribs in 2 or more places caused by blunt trauma and associated with underlying pulmonary injury. Can lead to instability of chest wall - disruption of bony cortex of rib, linear lucency thru the rib
sternum fx
caused by blunt trauma, associated with underlying cardiac injury - disruption of bony cortex of sternum, linear lucency or displaced sternal segment
pectus carinatum (pigeon breast)
congenital defect - caused by anterior protrusion of the lower sternum and xiphoid process - usually benign condition but could lead to cardiopulmonary complications in rare cases
pectus excavatum (funnel chest)
congenital defect - deformity - depressed sternum. Rarely interferes with respiration but often is corrected surgically for cosmetic reasons
metastases
malignant neoplasms that spread to distant sites via blood and lymphatics. Ribs are common sites of metastatic lesions
osteolytic
destructive lesions with irregular markings - irregular margins and decreased density
osteoblastic
proliferative bony lesions of increased density
combo of osteolytic and osteoblastic
moth-eaten look - results from mix of destructive and blastic lesions
osteomyelitis
localized or generalized infection of bone and marrow associated with postop complications of open heart surgery, which requires sternum to be split. Most common cause - bacterial infection- erosion of bony margins
RAO sternum rotation
15-20° - 15 for larger, 20 for thinner
If recumbent RAO sternum can't be done
do LPO or supine with 15-20° mediolateral angle
kVp for lateral sternum
70-75
kVp for ribs below the diaphragm
70-80
CR for sternoclavicular jts
T2-T3 (3" distal to vertebra prominens)
Arms for lateral sternum
drawn back
SID for lateral sternum
60-72" or use 11x14 if can only use 40"
SID if doing bilateral PA/AP ribs
72" to minimize magnification AND pt dose
For posterior ribs do AP or PA?
AP
respiration for above diaphragm
suspend on inspiration
respiration for below diaphragm
suspend on expiration
Oblique rotation for sternoclavicular jts
10-15°
Less obliquity 5-10° to visualize OPPOSITE jt next to vertebral column
When will a PA and lateral chest be requested
to rule out pneumothorax, hemothorax
For right axillary ribs, do
LAO or RPO
CR for above the diaphragm ribs
T7 - 3-4" below jugular notch
CR for below the diaphragm ribs
midway between xiphoid process and lower costal margin
IR for above the diaphragm ribs
1.5" above shoulder
IR for below the diaphragm ribs
at iliac crest