Lungs and Posterior Mediastinum Flashcards
Where does the trachea begin and end?
Begins at the inferior border of the larynx and end at the bifurcation into the primary bronchi at the sternal angle
What prevents the trachea from collapsing under normal conditions?
The C-shaped cartilages
What happens to the C-shaped cartilages as you move toward the bronchi?
- They lose their c-shape and become plates of cartilage
- These still serve to keep the lumen of the air tube open
- no longer called C-shape cartilages once you get to the bronchi
Where is the cough reflex stimulated?
At the mucosa covering the carina
What is the carina?
Name of the final tracheal cartilage located at the tracheal bifurcation (at the sternal angle)
If you choke, which bronchus are the food particles most likely to end up in and why?
Right because it straighter, larger, and a more direct continuation of the trachea
What effect does the presence of the heart and great vessels have on the morphology of the left broncus?
they make it course at a sharper angle
What happens to the cartilage as you move from primary bronchi to segmental and subsegmental bronchi?
Loss of cartilage as the branching gets more extensive
What keeps the subsegmental bronchii from collapsing past the point where the rings of cartilage end (bronchioles)?
Negative pressure acts to keep the lumen of the bronchioles open
Note: smooth muscle fibers and elastic fibers regulate the size of this lumen
What makes up the walls of the bronchioles?
Mucosa, submucosa, elastic fibers, and smooth muscle
What differentiates a bronchiole from a respiratory bronchiole?
The presence of isolated alveoli along the walls of the bronchioles
List the structures that lead from the respiratory bronchiole to an alveolar sac.
Respiratory bronchioles
Alveolar ducts
Atrium
Alveolar sacs (clustered around atrium)
What structural changes are caused by edema fibrosis?
Increased distance between RBCs in the alveolar capillaries and the air in the alveolar space
What is pneumothorax?
The presence of air in the cavity between the lungs and chest wall causing lung collapse
What is the cause of lung collapse observed in pneumothorax?
Elastic and smooth muscle that are present to help regulate lumen size collapse when the negative pressure in the pleural cavity is lost
NOTE: this is the basis of collapse anytime there is fluid in the pleural cavity
T or F: everything until you get to the respiratory bronchioles, where alveoli start to appear is called dead space
True
Where can gas exchange take place in the respiratory system?
Only between the respiratory membrane in the alveolus
T or F: to maintain sufficient O2 and CO2 levels the lungs must only take in more air than the volume of the dead space
True
T or F: increased distance of diffusion across the respiratory membrane has a greater affect on CO2 than oxygen?
False, CO2 moves 10x faster across the membrane so any increase in distance will be more devastating to O2 diffusion
What 4 common processes that impair lung function by increasing diffusion distance?
Smoking - accumulation of particles
Fibrosis - too much CT in lungs
Edema - more fluid to diffuse across
Infections - bacterial accumulation or secretions
What barriers must O2 cross in order to enter an alveolar capillary in a normal lung?
- Surfactant
- Alveolar epithelial cells
- capillary endothelium
- plasma inside capillary
**note there is a basal lamina and CT associated with 2 and 3.
What would you expect to happen to the heart as a result of pulmonary embolism?
Increased pressure on the right side as it tries to push blood past the occlusion
What is a bronchopulmonary segment and what does it consist of?
Bronchopulmonary segment contains several components and occurs on the tertiary branches of the bronchi
Associated structures:
- Pulmonary Artery (deoxgenated blood)
- Bronchial Artery (oxygenated blood)
- Pulmonary vein (oxygenated blood)
Compare the bronchial and pulmonary arteries
Bronchial - High pressure, Low Flow
Pulmonary - Low Pressure, High Flow
What are the locations of the veins and arteries in the bronchiole pulmonary segment?
- arteries are central within the segment
- veins are peripheral
Where do bronchial arteries end?
- they stop at the respiratory bronchioles because they are no longer needed
What feature lies just deep to the 4th rib and follows its path from the midclavicular line to the sternum?
Horizontal fissure
Where would you place the stethoscope to listen to the sounds of the inferior lobe of the lung?
On the back below the 6th rib (probably on the posterior side)
What feature lies deep to the ribs and crosses the 5th intercostal space in the mid-clavicular line and follows the 6th rib to the sternum?
Oblique fissure (both R and L lungs)
Where would you place the stethoscope to listen to breath sounds in the middle lobe?
below the 4th rib
Where would you place the stethoscope to listen to sounds in the superior lobe?
Above the 4th rib
What feature of the left lung is comparable to the middle lobe of the right lung?
the linguina
What lung feature projects through the thoracic inlet into the root of the neck?
apex
What is the hilum?
Where the structures of the root of the lung leave the mediastinum and enter the substance of the lung
What is the lingula?
Inferior aspect of the left superior lobe
T or F: the cardiac impression is a feature that can be found on both right and left lungs?
FALSE
What structure(s) within the hilum are typically located posterior and superior to the pulmonary veins?
Secondary and primary bronchi
Where are the pulmonary arteries located on the R and L sides?
Right:
anterior to the bronchi and between the bronchi and pulmonary veins (maintains anterior position to bronchi throughout course)
Left:
Up and bronchus to remain mostly in a posterior position throughout the course
From where do the two left bronchial arteries arise?
Anterior aspect of the thoracic aorta near the tracheal bifurcation
Where does the single right bronchial artery arise from?
the first right posterior intercostal branch of the aorta
Where does the left bronchial vein drain?
Hemiazygos vein
Where does the right bronchial vein empty?
azygos vein - near its junction with SVC
How many secondary bronchi are in the right and left lungs?
2 in the left lung, and 3 in the right
Note: there is a secondary bronchii for each lobe
What branches are given off from the vagus n. on the posterior side of the root of the lung, and what type of fibers are these?
- Pulmonary Branches given off here
- Branches: Postganglionic, GVE, Parasympathetic
What does Vagal motor stimulation cause in the lungs?
Constriction of the bronchial smooth muscle
secretion of bronchial mucus glands
Vasodilation
What do afferent fibers from the vagus n. do in the lungs?
- Detect stretching of muscle fibers in the bronchial tree
- Also contains fibers used in the COUGH reflex
What is the affect of sympathetic stimulation on the lungs?
- dilation of bronchi
- reduction in mucous secretion
- vasoconstriction
Where does the thoracic duct enter venous flow?
at the junction of the internal jugular and subclavian veins
What pulls lymph fluid into the venous flow?
Low pressure created by the flowing deoxygenated blood (Bernoulli’s principle)
What is the consequence of a faulty lymphatic return to the venous flow?
Edema
What is the thoracic duct?
The final lymph channel that drains 3/4 of the body (upper left quadrant and both lower quadrants)
What drains the upper right quadrant in the lymph system?
Right lymphatic duct
What is responsible for draining the right side of the head and neck?
Right lymphatic duct
Where does the thoracic duct begin?
at the cysterna chyli (just inferior to the diaphragm at the aortic hiatus
Where does the superficial plexus of lymphatics lie?
Just deep to the visceral pleura
Where can the deep lymphatic plexus be found?
In the submucosa and surrounding connective tissue of the bronchi
Where do lymphatics from both the deep and superficial plexus of lymphatics drain?
In the bronchopulmonary nodes
What group of lymph nodes lie deep to the carina?
Inferior tracheobronchial nodes
Where does lymph from the lungs ultimately drain the majority of the time?
Right thoracic duct for both lungs
Describe the path of the esophagus?
- Enters superior mediastinum at the midline and is just anterior to the thoracic vertebral bodies and continues downward until it makes a left turn around T10 to enter the stomach
Describe the innervation and musculature of the esophagus.
Upper 1/3:
GSE in the recurrent layngeal nn.
Striated muscle
Lower 2/3:
GVE in the vagus n.
Smooth muscle
What is the most superior sphincter in the esophagus and what is its job?
- The upper esophageal sphincter
- opens during the swallowing reflex and closes to minimize regurgitation
What is the most inferior esophageal sphincter and what is its job?
- lower esophageal sphincter
- keeps stomach contents from refluxing back toward the larynx
Aside from the upper and lower esophageal sphincters, what is another point in the esophagus where constrictions could occur?
- Where the trachea passes deep to the tracheal bifurcation, the left bronchus can press on the trachea causing constriction
Why are esophageal sphincters important?
- several pathologies can arise at these point
E.g.
Sphincter dysfunction and the formation of diverticula that can trap food and become infected
What are some of the effects diverticula in the esophagus?
- they can get infected
- can cause regurgitation
- bad breath
- aspiration pneumonia
What two two nerves divide to make the parasympathetic portion of the esophageal plexus?
right and left vagal nerves
How do nerves of the esophageal plexus enter the abdomin?
Through the esophageal hiatus in the diaphragm around T10
T or F: splanchnic nerves arise from the sympathetic trunk
True
T or F: splanchnic nerves typically contain post-ganglionic fibers
False - always preganglionic because they still need to synapse in the collateral ganglia
From what chain ganglia do the greater, lesser, and least splanchnic nerve arise?
T5-T9 ganglia (greater)
T10-T11 ganglia (lesser)
T12 ganglion (least)
At what vertebral level does the thoracic aorta descend into the abdominal cavity and what structure must it pass through to get there?
T12
-Must pass through the aortic hiatus in the diaphragm
What gives rise to the intercostal arteries?
1-2 originate from the subclavian a.
3-11 branch from the thoracic aorta
From major artery do the bronchial and esophageal arteries branch from?
Aorta
What veins drain the posterior mediastinum?
azygos system of veins:
azygos
hemiazygos
accessory hemiazygos
What two veins come together to pierce the diaphragm as the azygos vein and what is the area where this vein pierces?
Right ascending lumbar vein
Right subcostal vein
azygos passes through the aortic hiatus
T or F: the azygos vein can be found on the left side of the vertebral column, and it drains the left anterior intercostal veins
FALSE, it is found on the RIGHT side of the vertebral column and drains the RIGHT POSTERIOR intercostal veins
How does azygos receive blood from posterior intercostal spaces 2-4?
These drain into the right superior intercostal vein which drains into azygos
How are the left posterior intercostals drained?
Rib 1-3: Right superior intercostal vein
Rib 4-8: accessory hemiazygos vein
Rib 9-12: hemiazygos vein
What venous system in the thorax is incredibly important for collateral circulation and has very few valves?
Azygos
What vein might become enlarged from an occlusion in the superior vena cava?
azygos
What three major hiatuses exist in the diaphragm?
IVC hiatus T8
esophageal hiatus T10
Aortic hiatus T12
Which hiatus in the diaphragm pierces the central tendon?
IVC hiatus
What hiatus in the diaphragm is bounded on the right and left sides by the crura of the diagphragm?
aorta hiatus
How does the relationship of the esophagus to the aorta change as you descend into the diaphragm.
aorta L and esophagus R to aorta posterior and esophagus anterior
