Bronchi, lungs, pleura and diaphragm Flashcards
Where should the trachea be located
Central
If not- indication of pathology
Swallowing and breathing can also cause positional shifts.
Describe the trachea
Extends from vertebral level C6 to T4/5
Held open by C-shaped cartilage rings
Lowest ring has a hook – carina (keel of ship)
The oesophagus continues into the posterior mediastinum
Describe the relations of the trachea to other structures
As the trachea passes through the superior mediastinum, they are crossed laterally by the azygos vein (right) and arch of aorta (left)
Describe the primary bronchi
formed at T4/5, with the right wider and more vertical (STERNAL ANGLE) - inhaled objects likely to enter right lung as more vertical and wider.
Describe the lobar (secondary bronchi)
formed within lungs to supply lobes (2 on left, 3 on right)
Supply the lobes
Describe the segmental bronchi
supply the bronchopulmonary segments (further subdivisions to supply independent units of lung tissues known as bronchopulmonary segments)
Describe the bronchial tree
Trachea divides into two main bronchi at vertebral level T4/5:
Right and left main (primary) bronchi divide into:
Lobar (secondary) bronchi - supplying the lobes (2 left, 3 right)
The lobar bronchi further subdivide into segmental (tertiary) bronchi supplying self-contained independent units of lung tissue named bronchopulmonary segments
What is meant by the bronchial tree
Branching pattern of trachea into main, lobar and segmental bronchi
What is C7
Prominent vertebrae- can be palpated
What happens to the segmental bronchi
The segmental bronchi give rise to multiple generations, ultimately bronchioles, which further subdivide and supply the respiratory surfaces.
The walls of the bronchi are held open by discontinuous elongated plates of cartilage, but these are not present in bronchioles
Why is the trachea open posteriorly
To allow the oesophagus to expand (e.g when eating)
What is meant by a bronchopulmonary segment
smallest functionally independent region of the lung so can remove one without affecting others/upstream
Has its own blood supply (pulmonary artery), innervation and airway
Tributaries of the pulmonary vein tend to pass intersegmentally around the margins of the segment..
How many bronchopulmonary segments are there
10 in each lung- however some fuse in the left lung
Describe the lungs
essential respiration organs situated in thorax and separated by mediastinum; each lies freely in pleural cavity (lined by pleural membranes held together by tension of fluid) apart from attachment to heart via pulmonary vessels and trachea and lung room (hilum)
Describe the shape of the lungs
The lungs are conical in shape
Describe the base of the lungs
concave
rests on convex surface of diaphragm
Describe the apex of the lungs
thoracic inlet oblique - apex rises 3-4 cm above
level of first costal cartilage- into root of neck.
Describe the surfaces of the lungs
The surfaces of the lungs relate to the structures that the lungs are sat in.
Costal- lies immediately adjacent to the ribs and intercostal spaces
Mediastinal surface- lies against the mediastinum anteriorly and vertebral column posteriorly- contains hilum
Inferior- diaphragm
Describe the borders (edges) of the lungs
Inferior border- sharp, separates base from the costal surface
Anterior and posterior- separate costal surfaces from the medial surface- smooth and rounded.
What does the diaphragm separate
right lung from right lobe of liver
left lung from left lobe of the liver, stomach & spleen
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
What is found above and behind the cardiac impression of the lungs
Above and behind cardiac impression - hilum of the lung where vessels, bronchi & nerves enter & leave the mediastinum
Which structures indent the costal surfaces of the lungs
The ribs
Describes the lobes of the left lung
Oblique fissure separates the superior and inferior lobes
Superior lobe lies above the fissure – includes:
Apex
Most of anterior part of lung
The inferior lobe is in contact with posterior and inferior borders
Describe the other key features of the left lung
The inferior portion of the medial surface is notched because of the heart’s projection into the left pleural cavity from the middle mediastinum.
From the anterior border of the lower part of the superior lobe a tounge-like extension (lingula) projects over the heart bulge.
Groove for aorta
Cardiac impression
Groove for left subclavian artery
Groove for the left brachiocephalic vein ( second groove).
Describe the lobes of the right lung
The right lung has three lobes and two fissures
Normally, these lobes are freely moveable against each other because they are separated, to the hilum, by invaginations of the visceral pleura.
Oblique fissures- separate the inferior lobe from the superior and middle lobes
Horizontal fissure- separates superior from the middle lobe.
Describe the other features of the right lung
Groove for right subclavian artery Groove for oesophagus Groove for SVC Groove for azygos vein Groove for IVC
Describe the root (hilum) of the lung
The root of each lung is a tubular collection of structures that together attach the lung to structures in the mediastinum (heart and trachea)
It is covered by a sleeve of mediastinal pleura that reflects onto the surface of the lungs as visceral pleura. The region outlined by this pleural reflection on the mediastinal surface is the hilum, where structures can enter and leave
The root and hilum are not the same thing.
root is inside the hilum.
Pleural reflection occurs at the hilum where the pulmonary ligament attaches to lungs
What structures are found inside the hilum
Principal (primary) bronchus
Pulmonary artery (deoxygenated blood from RV)
2 pulmonary veins (oxygenated blood to LA)
Bronchial arteries (oxygenated blood from descending aorta) and veins
Pulmonary plexus of nerves (autonomic)
Lymph vessels and nodes
Describe the positioning of the structures inside the hilum
Generally, the pulmonary artery is superior at the hilum, the pulmonary veins are inferior, and the bronchi are somewhat posterior in position.
On the right side, the lobar bronchus to the superior lobe branches from the main bronchi in the root, unlike on the left where it branches within the lung itself and is superior to the pulmonary artery.
Which lung is bigger
The right (because the middle mediastinum bulges more to the left).
Describe the difference between the pulmonary arteries and veins
Pulmonary arteries- carry deoxygenated blood to the lungs
Pulmonary veins- carry oxygenated blood to the lungs.
What is the role of the brachial arteries
systemic- carry oxygenated blood to the lungs.
Describe the pulmonary ligament
used to be an open vessel- no longer- just a thickening of tissue- no function- expands as you breathe in.
What is meant by the pleura
A thin layer of flattened cells supported by connective tissue that lines each pleural cavity and covers the exterior of the lungs
Describe the two pleural layers
2 layers
visceral pleura - covers surface lungs and lines fissures between the lobes
parietal pleura - lines inner surface of chest walls
Visceral and parietal pleura are continuous with each other around the root of the lung – this is the hilum
Describe the pleura in health
In health:
Pleural cavity is collapsed, but moist surfaces allow lungs to glide as they expand and collapse
Describe pleural origin
Pleural cavities inside chest wall
Lined by parietal pleura
Lung buds grow into them
Within covering of visceral pleura
What is meant by the pleural cavity
Is the potential space enclosed between the visceral and parietal pleurae. They normally contain a thin layer of serous fluid. As a result, the visceral pleura directly opposed and freely slides over the parietal pleura attached to the wall.
What is meant by the pleural recesses
The lungs do not completely fill the anterior or posterior inferior regions of the pleural cavities.
This results in recesses in which two layers of parietal pleura become opposed.
Expansion of the lungs into these spaces usually occurs during forced inspiration.
These recesses also provide potential regions for fluid to accumulate and be aspirated.
Describe the costomediastinal recesses
Anteriorly, a costomediastinal recess occurs on each side where costal pleura is opposed by mediastinal pleura- the largest is on the left side in the region covering the heart
Describe the costodiaphragmatic recess
Largest and most clinically important
Between costal pleura and diaphragmatic pleura
Recess between inferior margin of lungs and inferior margin of pleural cavities
Largest after forced expiration, shallowest after forced inspiration.
Describe breathing
Controlled by nervous system and produced by skeletal muscle
Brings about inhalation and exhalation of air into/out of the lungs, to ventilate the gas exchange areas - alveolar sacs
capacity of thoracic cavity can be increased:
by movements of the diaphragm
by movements of the ribs
Describe movements of the pleural cavity in breathing
Pleural cavity is expanded by muscles in walls
Elastic lungs expand with the pleural cavity, sucking air down trachea and bronchi into lungs
Describe the role of the diaphragm in inspiration
Contraction of the diaphragm increases the vertical dimension of the thoracic cavity.
When it contracts, the diaphragm 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
Describe the costal margin
The margin of the diaphragm (black) is attached to the:
costal margin (lower border of the rib cage)
xiphoid process
ends of ribs 11 and 12
lumbar vertebrae
Describe the dome of the diaphragm
The dome of the diaphragm (red) bulges high inside the rib cage.
So high abdominal organs such as liver are covered by diaphragm, pleura and lung
Describe the movements of the ribs in breathing
Ribs elevated - anterior ends thrust forward and upwards - increases antero-posterior dimension of thoracic cavity.
At same time ribs are everted, increasing transverse diameter of thoracic cavity
Internal and external intercostal muscles stiffen the rib cage to increase efficiency of diaphragm
Explain the lateral movement of the ribs
Raising the costal margin widens the pleural cavities by raising drooping lateral parts of ribs
Describe the antero-posterior movement of the ribs
Raising the costal margin also raises drooping anterior ends ribs, tilting sternum upwards to increase antero-posterior diameter of pleural cavities
Describe expiration
Quiet expiration is a passive activity not requiring muscles
It depends on elastic recoil in the elastic tissue throughout the lungs and in the rib cage
In deep or forced expiration, this is assisted by the muscles of the abdominal walls that squeeze the abdominal organs against the diaphragm and pull the lower ribs downward
