3. Bronchi, Lungs, Pleura and Diaphragm Flashcards
Sternal angle
Point at which 2nd costal cartilage attaches
Posteriorly, this is at the vertebral level T4/5
What vertebral level does the trachea start and end at?
C6 to T4/T5
What is the name of the hooked cartilage at the bottom of the trachea?
Carina
Hooks under bifurcation of trachea into left and right main bronchus
What are the 3 divisions of the bronchi?
Primary
Lobar
Segmental
Primary bronchi
Formed at T4/5
Right is wider and more vertical than left: solid objects more likely found in right
Lobar (secondary) bronchi
Formed within the lungs
Supply the lobes of the lungs (more in right than left, as right has an extra lobe)
Segmental (tertiary bronchi)
Supply the bronchopulmonary segments
Lobes in each lung
Right: 3
Left: 2
What are the cartilaginous structures found at the top of the airway?
Thyroid Cartilage
Cricoid Cartilage
Thyroid cartilage in males and females
Larger in males than females
What is the clinical significance of the gap between the cartilaginous structures at the top of the airway?
In an emergency situation, a cricothyroidotomy can be performed by piercing a hole in the median cricothyroid ligament.
How many bronchopulmonary segments are there per lung?
10
Despite there being different number of lobes in each
What is the arrangement of bronchopulmonary segments? How is this advantageous?
Smallest, functionally independent regions that can be removed without affecting anything upstream (not in series)
Because they’re functionally independent they have their own nerve supply, blood supply and airway
How are the lungs arranged?
Each lies freely in its pleural cavity (filled with pleural fluid which creates surface tension between layers)
Free apart from its attachment to the heart (via pulmonary vessels) and trachea at the lung root (hilum)
Describe the 2 types of circulation to and from lungs
Pulmonary circulation: arteries take deoxygenated blood to lungs and veins return oxygenated blood to heart
Bronchial circulation: arteries takes O2 to lungs and veins remove deoxygenated blood
What do the vessels, nerves and bronchi from the mediastinum have to pass through to get to the lungs?
Root of the lung
Describe the shape of the lungs
Conical
Where is the apex of the lung?
Thoracic inlet oblique
3-4 cm above the level of the 1st costal cartilage
Describe the base of the lung
Concave
Rests on convex surface of diaphragm (dome superiorly)
What are the 3 edges of the lung?
Anterior
Posterior
Inferior
What are the 3 surfaces of the lung?
Costal (Outer, closest to ribs)
Mediastinal (Closest to heart)
Diaphragmatic (Rests on diaphragm)
What does the diaphragm separate the left and right lung from?
Right lung: from right lobe of liver
Left lung: from left lobe of the liver, stomach and spleen
Describe the posterior part of the mediastinal surface of the lung
Thick
In contact with thoracic vertebrae
Describe the anterior part of the mediastinal surface of the lung
Deeply concave: accommodates the heart
Cardiac impression larger on L than R because of position of heart
Describe the part above and behind the cardiac impression of the mediastinal surface of the lung
Hilum (pleural reflection) of the lung where vessels, bronchi and nerves enter and leave the mediastinum
What are the root and hilum?
Hilum: reflection in pleura
Root: is inside the hilum, structures going from lung to heart
Describe the left lung from a mediastinal aspect
Lingula projects forwards infront of heart (at front, flap, like a tongue)
Groove for aorta
Cardiac impression for heart
2 pulmonary veins from each lung
Describe the structure of the left lung
2 lobes: Superior (upper) Inferior (lower) Separated by oblique fissure Superior lobe lies above the fissure, includes: Apex Most of anterior part of lung
Describe the right lung from a mediastinal aspect
Grooves for major vessels
Groove for oesophagus at back
Describe the structure of the right lung
3 lobes:
Superior
Middle
Inferior
Separated by 2 fissures
Oblique fissure: separates inferior lobe from the other 2 lobes
Horizontal fissure: separates superior from middle lobe
Right lung is slightly larger than the left (as heart is located on left side)
What structures enter of leave the hilum of the lung?
Pulmonary artery 2 Pulmonary veins Primary bronchus Bronchial arteries Pulmonary nerve plexus Lymph vessels and nodes
Pulmonary trunk
Large artery emerging from right ventricle, which goes superiorly then posteriorly, before dividing into left and right pulmonary artery.
It’s the 1st vertically orientated blood vessel coming from the right ventricle.
What is the pulmonary ligament?
Inferior fold of pleura (below the hilum)
Thickening of tissue
Expands on inhalation and allows expansion of lung
Pleura
A thin layer of flattened cells supported by connective tissue that lines each pleural cavity and covers the exterior of the lungs
What are the 2 pleural layers?
Visceral pleura: covers surface of lungs and lines fissures between the lobes
Parietal pleura: lines inner surface of chest walls
Where do the visceral and parietal pleura become continuous?
At the hilum of the lungs
Describe the pleural cavity in health
Pleural cavity is collapsed (visceral and parietal mostly touching each other with small amount of fluid inbetween)
Moist surfaces allow lungs to glide as they expand and collapse
Heart location
Mainly centrally located, but projects downwards and towards left side
Lungs and pleural cavity locations
Lungs and pleural cavities are next to each other at top of chest
Pleural cavity at bottom is larger: only in deep inhalation lung will fill pleural cavity
What is the gap between the inferior surface of the lung and the inferior surface of the pleura called?
Costo-diaphragmatic recess
Where does the oblique fissure run?
Along 6th rib
Where does the horizontal fissure on the right side run?
From 4th costal cartilage and 4th rib runs laterally, directly out until it meets the oblique fissure
How does the diaphragm function as the main inspiratory muscle?
Contraction of the diaphragm increases the vertical dimension of the thoracic cavity.
-presses on the abdominal viscera which initially descend (because of relaxation of the abdominal wall during inspiration)
Further descent is stopped by the abdominal viscera, so more diaphragm contraction raises the costal margin
Increased thoracic capacity produced by diaphragm and rib movements in inspiration, reduces intrapleural pressure, with entry of air through respiratory passages and expansion of the lungs
What are the attachments of the diaphragm?
Costal margin
Xiphoid process
Ends of ribs 11 and 12
Lumbar vertebrae
How do the dimensions of the thoracic cavity change when inspiring?
Anteroposterior diameter increases
Transverse diameter increases
What causes expiration?
Expiration is PASSIVE
Caused by the natural elastic recoil of the lungs
What happens in forced expiration?
Abdominal muscle contracts pushing the abdominal viscera against the diaphragm and pulling the costal margin down.
