applied anatomy of the thorax Flashcards
what’s the largest muscle in the chest wall?
pectoralis major
what actions can pectoralis major do?
flexion
adduction
internal rotation
what are the attachment points of pectoralis major?
o Attaches to clavicle, sternum, ribs and humerus
where is pectoralis minor found?
underneath pectoralis major
where does pectoralis minor attach?
to the scapula and ribs
what are the attachment points of sternocleidomastoid?
mastoid process
sternum and clavicle
what nerve innervates the sternocleidomastoid?
spinal accessory nerve
what are the attachment points of the rectus abdominis?
costal margin and xiphoid process
pubic symphysis
what muscles are used in inspiration?
pec major, pec minor, SCM, external intercostals
what muscle is used in forced expiration?
rectus abdominis
what supplies the serratus anterior and what are the spinal levels?
long thoracic nerve C5-C7
where does the long thoracic nerve run?
runs on the superficial border of the muscle
what is the clinical relevance of the long thoracic nerve?
if you’re removing all the axillary lymph nodes in a radical mastectomy then it’s easy to damage this nerve winging of the scapula
how do intercostal nerves leave the spinal cord?
through the IV foramen
where do posterior intercostal arteries branch from?
thoracic aorta
where do anterior intercostal arteries branch from?
internal thoracic artery
where do anterior intercostal veins drain?
into the internal thoracic vein
where do posterior intercostal veins drain?
azygos –> superior vena cava
where are neurovascular bundles found?
innermost intercostal layer and internal intercostal
what is the pupose of thoracocentesis?
done to sample pleural fluid
how is thoracocentesis done?
- Needle inserted superior to rib to avoid damage to intercostal nerves
- Upright patient will have fluid accumulate in the costophrenic recess
- 9th mid-axillary line during expiration avoids the inferior border of the lung
what condition can a ruptured posterior intercostal artery caused?
haemothorax
where is a chest drain done?
5th intercostal space in the mid-axillary line
why does a chest drain happen higher in the chest than a thoracocentesis?
Happens higher up than thoracocentesis bc you’re trying to avoid the liver
what nerve innervates the diaphragm?
phrenic nerve
C3-C5
where does the vena cava enter the diaphragm?
T8
where does the oesophagus enter the diaphragn?
T10
at what level is the aortic hiatus?
T12
what does the parietal pleura cover?
thoracic wall and superior surface of diaphragm
what does the visceral pleura cover?
covers external lung surface
where is the pleural cavity found?
between the pleural layers
which pleural layer produces pleural fluid?
parietal pleura
what is the function of pleural fluid?
o Reduce the friction when you breathe
o Keeps the lungs stuck to the parietal layer
oKeeps the lungs inflated
explain the nerve supply of the visceral pleura
same as the lungs: sympathetic and parasympathetic. Not able to perceive pain
explain the nerve supply of the parietal pleura
same as the chest wall: innervated by the intercostal nerves and the phrenic nerve. Can feel pain.
what aspect of the chest wall are the intercostal nerves found?
lateral
what aspect of the chest wall is the phrenic nerve found on?
medial
when would you feel a tumour in the lung tissue?
when it got so big until it touched the parietal pleura
on a normal chest x ray, should the pleura be visible?
no
how is the costophrenic recess formed?
parietal pleura continues 2 ribs inferior to the lungs
ends up with a space under the inferior border of the lung
why is it best to look for a pleural effusion using a lateral view?
Diaphragm is deeply domed so the deepest point of the CPR is at the back of the chest cavity.
when can you see an effusion with a lateral view?
when there’s about 100ml of fluid
when can you see an effusion with an AP view?
need about 200ml of fluid
where is the apex of the lungs?
2cm above the clavicles
where is the cardiac notch?
4th rib
where are the borders of the lungs found?
6th rib - MCL
8th rib - MAL
10th rib
what are the pleural boundaries?
ribs 8, 10 and 12
describe the respiratory tree
trachea - main bronchus - lobar bronchus - segmental bronchi - conducting bronchioles - terminal bronchioles - respiratory bronchioles - alveolar ducts - alveolar sacs
describe the structure of the trachea
C shaped rings of cartilage anteriorly and smooth muscle posteriorly
how is the right bronchus different to the left?
more vertical and larger
what is the clinical relevance of the right bronchus being vertical?
anything aspirated is more likely to go to the right lung. Aspiration pneumonia is more likely to occur in the right lung
how many lobar bronchi do we have for each lung?
3 lobar bronchi in the right lung
2 lobar in the left
how many ribs should you normally see above the diaphragm on an x-ray?
5-7
how does hyper-expansion of the lungs look on an x-ray?
when more than 5-7 ribs can be seen above the diaphragm
explain the process of emphysema?
- Destruction of alveolar walls leading to permanent enlargement of air spaces
- Surface area dramatically reduced
- Loss of elastic tissue so less recoil of the lungs
- Narrowed bronchioles
- COPD – emphysema
why is there hyperextension of the lungs in emphysema?
o When air leaves the bronchioles, lungs will elastic recoi.
o COPD – less elastic recoil and bronchioles aren’t supported by as much tissue bc it’s all been destroyed. Air cant leave gets trapped
o Air doesn’t get expired so the lungs become hyperinflated
what divides the superior and inferior mediastinum?
angle of louis
what does the superior mediastinum contain?
great vessels, oesophagus, trachea, thymus, phrenic nerves, vagus nerves, recurrent laryngeal nerves, thoracic duct
describe the passage of the recurrent laryngeal nerve in the body?
branch of vagus nerve which loops around the arch of the aorta on the left and the subclavian artery on the right. Runs back up to the larynx where it supplies the vocal cords
where is the posterior mediastinum?
• Anterior to vertebrae T5-T12, inferior to sternal angle and posterior to pericardium
what does the posterior mediastinum contain?
azygos (and hemi-azygos), vagus, oesophagus, thoracic duct, thoracic aorta
what spinal levels are the sympathetic chain ganglion?
T1-L2
what does the sympathetic trunk control?
fight or flight response; pupil dilation, bronchodilation, cardiac acceleration, inhibition of digestion, filling of the bladder, peripheral vasoconstriction, piloerection
