Transcript Lung Anatomy - Learning

Lung Anatomy
Ben Barnard
Department of Radiology
Kimberley Hospital
Outline
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Basic morphology
Fissures
Bronchopulmonary segments
Pulmonary vessels
Bronchial vessels
Lymphatics
Lung roots
Pleura
• Radiological features
Basic morphology
• Surfaces
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Costal
Mediastinal
Apical
Diaphragmatic
• Right lung
– Three lobes
• Left lung
– Two lobes
– Lingula of the
upper lobe
corresponds to
right middle lobe
Lobules
• One terminal
bronchiole with lung
tissue forms an
acinus
• Acinus with vessels,
lymphatics and
nerves form the
primary lobule
• Three to five primary
lobules form a
secondary lobule
Interlobar fissures
• Oblique (major) fissure
– Extends from T4/T5 posteriorly to
the diaphragm antero-inferiorly
– Left major fissure is more
vertically orientated
– Undulating in course
– Medial aspect passes through the
hilum
– Lateral aspect is anterior to the
medial aspect at the level of the
hila and below
– Above the hila, the lateral aspect
is more posterior
Interlobar fissures
• Transverse (minor) fissure
– Separates upper and middle
lobes of the right lung
– Runs horizontally from the
hilum to the anterior and
lateral surfaces of the right
lung
– Level of the fourth costal
cartilage
– Posterior limit is the right
oblique fissure, which it meets
at the level of the 6th rib in the
midaxillary line
– Anatomically complete in only
33% of people and absent in
10%
Accessory fissures
• Azygos fissure
– Downward invagination of the azygos vein through the apical portion of the
right upper lobe
– Four pleural layers – two visceral and two parietal
• Superior accessory fissure
– Separates the apical segment of the right lower lobe from the other basal
segments
– Lies parallel and inferiorly to the transverse fissure
– Passes posteriorly from the right oblique fissure to the posterior surface of the
lung
• Inferior accessory fissure
– Separates the medial basal from the other right lower lobe segments
– Also called Twining’s line
• Left transverse fissure
– Separates the lingula from the rest of the left upper lobe segments
– Rarely seen
Azygos Fissure
Bronchopulmonary segments
• Each lobe is divided into several
bronchopulmonary segments
• Each is supplied by
– Segmental bronchus
– Segmental artery
– Segmental vein
• Each segment is named for its supplying bronchus
• Anatomy of the segmental bronchi is subject to
variations – the most common being the origin of
the apical segment bronchi from the trachea
Collateral air drift
• Very little connection between segments except via
– Pores of Kohn
• Openings in alveolar walls
• Connect adjacent alveolar lumens
– Canals of Lambert
• Connections between terminal bronchioles and adjacent alveoli
• Allow gas and fluid transfer between segments but not
between lobes
• Ventilation of a segment is thus possible when its
segmental bronchus is occluded = collateral air drift
Pulmonary arteries
• Pulmonary trunk
leaves pericardium
and bifurcates in
the concavity of
the aortic arch
anterior to the left
main bronchus
Right Pulmonary Artery
• Longer than the left
• Passes across the midline
below the carina and comes
to lie anterior to the right
main bronchus
• It bifurcates while still in the
hilum of the right lung
• An artery to the right upper
lobe passes anterior to the
right upper lobe bronchus
• Interlobar artery to the right
middle and lower lobes
passes with the bronchus
intermedius
Left Pulmonary Artery
• Left pulmonary artery spirals over
the superior aspect of the left
main bronchus to reach its
posterior surface
• It is attached to the concavity of
the aortic arch by the
ligamentum arteriosum
• Pulmonary arteries further
subdivide into segmental arteries
that travel with the segmental
bronchi, mostly on their
posterolateral surfaces
• Pulmonary arteries supply only
the alveoli
Pulmonary veins
• These do not follow the bronchial
pattern
• Tend to run in intersegmental
septa
• Two veins pass to each hilum
from lung tissue above and below
each oblique fissure
• They enter the mediastinum
slightly below and anterior to the
pulmonary arteries
• The lobar veins on the right may
remain separate – such that three
veins leave the right lung and
enter the left atrium
• The left pulmonary veins may
unite and enter the left atrium as
a single vessel
Bronchial arteries
• Supply the bronchi, visceral pleura
and connective tissues of the
lungs
• Arise from the thoracic aorta at
the T5 or T6 level
• Usually one right and two left
bronchial arteries
• Arise at the upper border of T5
• When a second bronchial artery
occurs on the right, it often arises
from the third intercostal artery
• Bronchial arteries may also arise
from the subclavian or internal
mammary arteries
• Tissues supplied by the bronchial
arteries drain to the pulmonary or
bronchial veins
Bronchial veins
• Form two distinct systems
• Deep veins
– Form a network around the
pulmonary interstitium
– Communicate freely with
pulmonary veins
– Form a bronchial venous
trunk that drains to the
pulmonary system
• Superficial veins
– Drain to the azygos vein on
the right and the accessory
hemiazygos vein on the left
Lymphatics
• Mediastinal lymph
nodes that drain the
lung are named
according to position
– Pulmonary nodes
– Bronchopulmonary
nodes
– Carinal nodes
– Tracheobronchial nodes
– Right and left
paratracheal nodes
Lymphatics
• Lymph vessels of the lungs are in superficial and deep
plexuses
• Superficial plexus beneath the pleura drains around the
surface of the lungs and the margins of the fissures to
converge at the hila and bronchopulmonary nodes
• Deep channels drain with the pulmonary vessels
towards the hila
• Few connections between superficial and deep
plexuses except at the hila
• Bronchopulmonary nodes drain to tracheobronchial
nodes and paratracheal nodes and then into the
bronchomediastinal trunks
Lung roots
• Roots of the lungs are
formed by structures
that enter and emerge at
the hila
• Lie at T5-T7 level
• Right lung root lies below
the arch of the azygos
vein and posterior to the
SVC and right atrium
• Left lung root lies below
the arch of the aorta and
anterior to the
descending aorta
Pleura
• Serous membrane that
– Covers the lung (visceral
pleura)
– Lines the thoracic cavity
(parietal pleura)
• Both layers are continuous
with each other anterior and
posterior to the lung root
• Below the hilum they hang
down in a loose fold called the
pulmonary ligament
• This allows descent of the lung
root in respiration and
distension of the pulmonary
veins
Pleura
• Visceral pleura extends into
the interlobar and accessory
fissures
• At rest the parietal pleura
extends deeper into the
costophrenic and
costomediastinal recesses than
the lungs and visceral pleura
• Parietal pleura is supplied by
the systemic vessels
• Visceral pleura is supplied by
the bronchial and pulmonary
circulation
Imaging of the Lungs
CXR PA
CXR L Lat
Pulmonary angiography
Bronchial angiography
CT
HRCT
Dual-Energy CT
MRI
MRA/MRV & Dynamic Airway Imaging
Isotope V/Q Scanning
SPECT
PET-CT
What’s missing?
Thank you
References
• Netter, F.H. (2011). Atlas of Human Anatomy, 5th ed.
Philadelphia: Saunders Elsevier
• Ryan, S., McNicholas, M., Eustace, S. (2011). Anatomy
for diagnostic imaging, 3rd ed. London: Saunders
Elsevier
• Butler, P., Mitchell, A.W.M., Ellis, H. (1999). Applied
Radiological Anatomy. Cambridge: Cambridge
University Press
• Karcaaltincaba M, Aktas A. Dual-energy CT revisited
with multidetector CT: review of principles and clinical
applications. Diagn Interv Radiol 2011; 17:181-194