Anatomy - the thorax Flashcards
where is the thorax?
located between the neck and abdomen
what is contained within the thorax?
thoracic cavity contains the lungs and heart
also contains the major blood vessels, part of the trachea and oesophagus
what protects the contents of the thoracic cavity?
thoracic wall
what are the functions of the thorax?
respiration
protection
conduit (passageway)
what Is the shape of the thorax?
narrower at top and wider at the bottom
goes from the neck to the abdomen
what does the thoracic wall consist of?
-sternum
-thoracic vertebrae (T1-T12)
-ribs and costal cartilages
-intercostal muscles fill the intercostal spaces
-arteries and nerves that supply it
are the pectoral muscles part of the thoracic wall?
no they are considered upper limb muscles
what makes up the thoracic cage?
skeletal framework, bone and cartilage
what is the thoracic cage?
provides rigidity and flexibility
what kind of joints are between the vertebrae and the ribs?
synovial plane joints so allow some movement
what are the true ribs?
costal cartilage attaches directly to the sternum - sternocostal joints
what are false ribs?
costal cartilage attaches to the cartilage above - interchondral joints (ribs 8-10)
what are floating ribs?
do not attach to the sternum at all (11+12)
what are the costovertebral joints?
head of the rib articulates with the superior Demi-facet of the corresponding vertebra and the inferior Demi-facet of the vertebrae superior to it
what is the costotransverse joint?
the tubercle of the rub articulates with the transverse process of the corresponding vertebra
where does the rib joint on to the spine?
between 2 vertebrae, joins via Demi-facets
which ribs are atypical in terms of joints?
1, 10, 12
rib 1 - head only articulates with T1
10 and 12 don’t have demi facets only articulate with one vertebra
what is the superior thoracic aperture?
the doorway between the thoracic cavity and the neck and upper limb
what is the inferior thoracic aperture?
provides attachment for the diaphragm
what separates the thoracic and abdominal cavities?
diaphragm
what clinical problems can cervicle ribs cause?
sometimes also have a cervical band of tissue that extends anteriorly, structures passing through the thorax can be interrupted by this cervical band
brachial plexus and axillary can be affected
what are the boundaries of the superior thoracic aperture?
bones and cartilage of thoracic cage, - T1, medial border of rib one on either side and superior border od manubrium
what are the attachments of the diaphragm?
L1-L3 vertebrae
inferior costal cartilages and adjacent ribs
xiphoid process
what is the principle muscle of respiration?
diaphragm
how much can the domes of the diaphragm project upwards?
reach the level of the 5th rib
what is the nerve innervation of the diaphragm?
phrenic nerve, C3-5
C3,4,5 keep the diaphragm alive
why is the right dome of the diaphragm higher than the left?
the liver sits here
which kidney sits higher?
the left kidney
how much does the diaphragm move during quiet breathing?
1-2cm
what happens to the diaphragm when we breathe in?
it contracts, flattens out to increase space in thoracic cavity
how much does the diaphragm move during forced breathing?
6-10cm
where do the muscle fibres of the diagram insert?
the inferior thoracicapeture margins
what is the thoracic cavity?
a conduit passageway, from throat, neck to abdomen
what is the caval opening?
hole in the central tendon,
what passes through the caval opening?
inferior vena cava at level of T8
what passes through the diaphragm at the level of T10?
oesophagus, throighthe oesophageal hiatus (in the muscle of the diaphragm)
when and where does the aorta pass through the diaphragm?
at T12 through the aortic hiatus. behind the diaphragm
what are the external intercostal muscles?
occupy intercostal spaces from posterior to costochondral junction
muscle fibres run anterioinferiorly
when are the external intercostals most active?
during inspiration
when they contract they lift the ribs up
when are the internal intercostals most active?
during expiration
when they contract they depress the ribs
what are the internal intercostal muscles?
occupy the intercostal spaces from anterior to angle of the ribs
muscle fibres run anteroposteriorly
what are the innermost intercostal muscles?
deep part of internal intercostal muscles
form an incomplete layer that is most obvious laterally
where do the intercostal neuromuscular bundles lie?
lie between internal and innermost intercostals
how do the ribs move when breathing?
they slope inferiorly therefor elevation of the ribs increases the anterioposterior lateral dimensions of the thorax
contraction of the diaphragm increases the superoinferior dimensions
what Are some accessory muscles of respiration?
sternocloidimastoid (from skull down to clavicle)
pectoris muscles
how can accessory muscles help with respiration?
fixing of the arm and pectoral girdle allows neck and arm muscles to assist rib elevation in forced breathing
which muscles can assist forced expiration?
abdominal muscles
what is the order from top to bottom of the intercostal neuromuscular bundle?
vein, artery, nerve
VAN
what is the groove called that the intercostal neuromuscular bundle sits?
subcostal groove
what is the smaller bundle called that sits superior to the rib called?
collateral branches
what roots form the intercostal nerves?
anterior rami of T1-T11
what spinal nerve form the subcostal nerve?
the anterior ramus of T12
what are the 2 branches of intercostal arteries?
anterior and posterior
they anastomose - important in establishing a collateral blood supply
where do the posterior intercostal arteries originate from?
aorta
where does the anterior intercostal artery originate from?
internal thoracic artery (or its branches)
where does the internal thoracic artery originate from?
subclavian artery
internal thoracic artery?
bifurcates into musculophrenic and superior epigastric arteries
what happens if there is a stricture or damage to the proximal aorta?
internal thoracic arteries and anterior intercostal arteries can expand to maintain blood supply
what does the musculofrenic artery supply?
diaphragm
what does the superior epigastric artery supply?
skin over proximal abdominal wall
what are the 3 subdivisions of the thoracic cavity?
pulmonary cavity
mediastinum
pulmonary cavity
what are the pulmonary cavities?
contain the lungs, completely separate
what is in the mediastinum?
the heart
what are the layers of the pericardium?
visceral layer, serous pericardium
parietal layer, serous pericardium
fibrous pericardium - forms sac around heart
what are the layers around the lungs (pleura)?
parietal pleura - connecte tissue layer
visceral pleura - closely associated with the thoracic wall
what are the pleural recesses?
potential spaces between the costal and diaphragmatic pleura that the lungs can move into during inspiration
what are serous membranes?
as an organ develops it pushes into a serous membrane which is like a water balloon.
the outermost layer is the visceral layer, the farther away part is the parietal.
there is a layer of fluid between the layers which lubricates
layers are continuous which represents blood vessels ect
what is the most important recess?
the costodiapragmatic recess as its most likely where fluid will pool
between which muscles does the neuruvascular bundles lie?
internal and innermost intercostal muscles
what is the safest route to insert a needle to perform thoracentesis?
costodriaphragmatic recess, superiori to rib, just high enough to avoid collateral bundle branches of intercostal nerve
what is a thoracotomy?
surgical procedure used to gain access into the pleural space
why is the 1st rib rarely fractured?
protected very well
what would happen with a spinal cord injury of C7?
Someone with a C6 – C7 injury is likely to still have some impaired diaphragmatic control, using accessory muscles of the back and chest more than someone without SC
what is the safest route of a thorocentesis?
The preferred site for the procedure is on the affected side in either the midaxillary line if the procedure is being performed in the supine position or the posterior midscapular line if the procedure is being performed in the upright or seated position
