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What is the thorax?
the region between the neck and abdomen
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What are the contents ofthe thorax?
- heart
- lungs
- structures passing between neck and abdomen
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What is the shape of the thorax?
truncated cone with an inlet (where the neck joints the thorax) and an outlet, which is closed off by repiratory diaphragm
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The bony thorax consists of which structures?
- 12 thoracic vertebrae
- 12 pairs of costae (ribs and costal cartilages)
- sternum consiting of manubrium, body and xiphoid process
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What are the thoracic apetures?
- thoracic inlet
- thoracic outlet
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What are some other names for the thoracic inlet?
- superior thoracic aperture
- thoracic outlet (to clinicians)
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What is another name for the thoracic outlet?
inferior thoracic aperture
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What is the costal margin?
where costal cartilages of ribs 7-10 blend together
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What are the bony boundaries of the thoracic inlet?
- body of 1st thoracic vertebra posteriorly
- 1st pair of costae laterally
- manubrium anteriorly
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What are the bony boundaries of the thoracic outlet?
- body of 12th thoracic vertebra posteriorly
- 11th and 12th costae laterally
- Xiphoid process and costal cartilages 7-10 anteriorly
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What does the respiratory diaphragm separate?
thorax from abdomen
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What closes off the thoracic outlet?
respiratory diaphragm
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How high does te dome of the diaphragm rise to provide protection to thoracic and some abdominal viscera?
rises to level of 5th intercostal space on right side and 6th intercostal space on the left side
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What makes up the sternum?
- manubrium
- body
- xiphoid process
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What does the manubrium articulate with?
- clavicles
- 1st pair of ribs
- 2nd pair of ribs
- body of sternum
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Where does the manubrium articulate with the clavicles?
by way of sternoclavicular joints
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Where does the 2nd pair of ribs articulate with the manubrium?
at sternal angle
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Where does the body of the sternum articulate with the manubrium?
at sternal angle
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Is the sternal angle the same between men and women?
no
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Is the sternal angle more acute in women or men? Why?
- more acute in women
- men typically have larger thoracic cage and therefore have bigger heart and lungs
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What is the body of the sternum composed of?
four fused stenebrae
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Are the four sternebrae making the body of the sternum ever not fused?
yes, they are separate in infants
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What does the body of the sternum articulate with?
- manubrium
- costal cartilages 2-7
- xiphoid process
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What does the manubriosternal joint allow?
hinge-like movement of body both anteriorly and posteriorly
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The manubriosternal joint faciliates increased repiration by allowing what?
expansion of thoracic cavity
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Where is the xiphisternal joint?
at level of T8 vertebrae
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Is the xiphisternal joint easily palpated?
yes
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When is the tip (inferior point) of the xiphoid process palpated?
with discomfort
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How many points does the xiphoid process have?
usually one but having two points (bifid) is common
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What is the shape of the xiphoid and how long is it?
length and shape are highly variable from person to person
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How many types of ribs are there?
3
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What are the 3 types of ribs based on?
their attachments to the sternum
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What are the 3 classifications of ribs?
- true ribs
- false ribs
- floating ribs
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Which ribs are true ribs?
1-7
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What makes ribs 1-7 true ribs?
costal cartilages attached directly to sternum
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Which ribs are false ribs?
8-10
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What makes ribs 8-10 false ribs?
have their costal cartilage attached indirectly to the sternum
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Which ribs are floating ribs?
11-12
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What makes ribs 11 and 12 floating ribs?
do not have any attachment to sternum
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Muscle layers of the intercostal spaces consist of the following three itercostal muscles:
- superficial: external intercostal
- middle: internal intercostal
- deepest: innermost intercostal
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The most superficial layer of the intercostal spaces consists of which muscles?
external intecstal
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Where do the external intercostals extend?
from tubercles of ribs to junction of costal cartilages with bony ribs
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Where does the external intercostal membrane pass?
from anterior margin of muscle to lateral borde of sternum
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What is the orientation of the fibers of the external intercostal muscles?
inferomedial orientation
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What happens when external intercostals contract?
ribs are elevated
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The middle layer of the intercostl spaces consists of which muscles?
internal intercostals
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Where do internal intercostals extend?
from sternum to mid-axillary line
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The internal intercostal membrane passes where?
from lateral margin of this muscle to the region of the vertebral column to fuse with supeiror costotransverse ligaments
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What is the orientation of the fibers of the internal intercostal muscles?
inferolateral
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What is the action occurs upon contraction of the internal intercostals?
ribs are depressed
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The deepest layer of the intercostal spaces consists of which muscles?
innermost intercostals
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Where do the innermost intercostals extend?
from angles of ribs to just anterior of the mid-axillary line
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The innermost intercostal membrane passes where?
from anterior border of muscle to lateral border of transverus throacis muscle
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The fibers of the innermost intercostals have he same orientation and function as which muscle?
internal intercostal
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Where does transverus thoracis muscle extend?
from posterior surface of lower 2 of the body of the sternum and the xiphoid process to the costochondral junction of ribs 3-6
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How many transverus thoracis muscles are there?
number varies from person to person
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What is the function of transverus thoracis muscle?
depress ribs
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Where do intercostal nerves come from?
ventral primary rami of T1-11
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The motor branches of the intercostal nerves innervate what?
intercostal muscles
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The cutaneous branches of the intercostal nerves provide what?
sensory innervation to the skin on the lateral and anterior surfaces of the thorax and abdomen
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How many pairs of posterior intercostal arteries are there?
9 pairs
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The posterior intercostal arteries branch from what?
descending aorta
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Where are the posterior intercostal arteries located?
between two deepest layers of intercostal muscles in intercostal spaces 3-11
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The posterior intercostal arteries have muscular branches that supply what?
intercostal, pectoral, and serratus anterior muscles
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In intercostal spaces 3-5 the lateral branches of the posterior intercostal arteries supply what in females?
breasts
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Supreme thoracic arteries are branches of what?
axillary
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What do supreme thoracic arteries supply?
intercostal spaces 1-2
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Supreme intercostal arteries are branches of what?
costocervical trunk
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What do the supreme intercostal arteries supply?
intercostal spaces 1-2
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What are the branches of the internal thoracic artery?
- anterior intercostal
- superior epigastric
- musculophrenic
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Where does the superior epigastric artery go?
rectus abdominus
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The anterior interostal arteries are branches of what?
internal thoracic
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Where are the anterior intercostal arteries found?
in intercostal spaces 1-6
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What do the anterior intercostal arteries supply?
skin, intercostal muscles, breasts, and thymus gland (located in anterior mediastinum)
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The musculophrenic artery is a terminal branch of what?
internal thoracic
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What does the musculophrenic artery provide?
anterior intercostal arteries to intercostal spaces 7-9
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The musculophrenic artery has branches going where besides to intercostal spaces?
respiratory diaphragm
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What separates right and left pleural cavities?
mediastinum
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What is the mediastinum?
three dimensional space located between the pleural cavitis
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What does the parietal pleura line?
pleural cavity
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The parietal pleura has several surfaces named for what?
structures it contacts
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What is costal pleura attached to?
ribs and intercostal space
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What is the mediastinal pleura adhered to?
mediastinum
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The diaphagmatic pleura adheres to what?
superior surface of respiratory diaphragm
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The cervical pleura lines what?
pleural cavity avove level of 1st ribs, in the root of the neck
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What does the visceral pleura cover?
surfaces of the lungs
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The connecting layer of pleura surrounds what?
the root of the lungs like a sleeve, covering structures passing into lungs
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Name the lines of reflection ofparietal pleura:
- vertebrl reflection
- sternal reflection
- costal reflection
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Where is the vrtebral reflection?
where costal and mediastinal pleurae become continuous posteriorly
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Where is the sternal reflection?
where costal and mediastinal pleurae become continuous anteriorly
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Where is the costal reflection?
where costal and diaphragmatic pleurae become continuous inferiorly
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Where do pleural recesses occur?
where two layers of parietal pleura form an acute angle and are in direct contact with each other in the living person
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Do the lungs occupy the pleural recesses?
normally they do not
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What may collect in these recesses?
with certain respiratory infections various substances (such as pus, fluid, or dead cells)
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Where is the right costodiaphragmatic recess?
laterally along costal reflection
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Where is the left costodiaphragmatic recess located?
laterally along costal reflection
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Where is the left costomediastinal recess located?
- anteriorly along sternal reflection
- between upper lobe of left lung and the heart
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The visceral pleura covering the lungs is normally in contact with what?
parietal pleura a potential space is located between these pleural layers
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What do the pleural cavities contain?
pleural fluid
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Where is pleural fluid produced?
pleural membranes
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What does the pleural fluid do?
lubricates surfaces of same membranes, preventing adhesions
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Where are the lungs found?
in pleural sacs, not pleural cavities
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What are pleural sacs?
spaces contained within the visceral pleurae
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What structures pass through the superior thoracic aperture?
- cervical parietal pleura
- ??
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Where are the intercostal vessels (nn/aa/vv)?
running between innermost and internal intercostal mm
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What is the potential space between the visceral and parietal pleura?
pleural cavity
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The visceral pleura is continuous with what?
parietal pleura
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What are the pleural recesses?
areas with no lung tissue
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What are places inside the pleural cavity where fluid might accumulate during infections?
costodiaphragmatic recesses
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Where can you have a penetrating wound that enters the pleural cavity without going through intercostal spaces?
- 1. above the first rib (pierces cervical pleura)
- 2. costovertebral angle
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What happens if the pleural cavity is punctured?
collapsed lung
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Where are the costovertebral angles?
between the lower border of the 12th rib and the diaphragmatic pleura (on top of diaphragm)
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If a needle goes into the costovertebral angle, it would puncture what and cause what?
puncture parietal pleura and cause a collapsed lung
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