Intro to Main Structures of the Thorax Flashcards
What is the pericardium?
membrane enclosing the heart
divides into the fibrous and serous pericardium
Describe the fibrous pericardium
outer
very tough and not distensible
attached inferiorly to diaphragm by pericardiophrenic ligaments
blends into adventitia of great vessels - superiorly
Describe the serous pericardium
made up of: visceral (epicardium) and parietal layer (lines fibrous pericardium)
both composed of flattened layer of epithelial cells (mesothelium)
potential space (pericardial cavity) lies between
What forms the anterior part of the heart?
mostly right ventricle
bit of left
What forms the inferior/diaphragmatic part of the heart?
mostly left ventricle
bit of right
What forms the posterior/base part of the heart?
mostly left atrium and pulmonary vein
bit of right
What forms the pulmonary part of the heart?
mostly left ventricle in cardiac notch of left lung
What forms the apex of the heart?
left ventricle, usually posterior to left ics 5 in adults
Superior border of the heart
left costal cartilage 2 to right costal cartilage 3
Right border of the heart
convex to right
right cc3 to right cc6
mainly SVC and IVC
Inferior border of the heart
lies on diaphragm central tendon
right cc6 to left ics 5
mainly right ventricle and some left
Left border of the heart
convex to left
left ics 5 back to left cc 2
mainly left ventricle and may be some left atrium
Valves of the heart
pulmonary aortic bicuspid/mitral tricuspid all are retrosternal and close to midline PAMT
Pulmonary valve location
medial to left cc3
Aortic valve location
medial to L ics3
Bicuspid valve location
medial to L cc4
Tricuspid valve location
medial to R ics4
Where is the best place to hear valves for ascultation?
downstream of valve positions
Where to hear sound of pulmonary valve and what sound?
left ics 2 near sternal edge
dup
Where to hear sound of aortic valve and what sound?
right ics 2 near sternal edge
dup
Where to hear sound of bicuspid valve and what sound?
left ics 5 at midclavicular line
lub
Where to hear sound of tricuspid valve and what sound?
left ics 5/6 near lower sternal edge
lub
What is the pleura?
a serous membrane divided into parietal and visceral layers which surround the lungs and contain the pleural cavities
Parietal pleura
lines thoracic cavity lateral to mediastinum
sensory: intercostal and phrenic nerves, therfore sensitive to pain
Visceral pleura
covers lung and follows lung fissures
supplied by autonomic nerve - not sensitive to pain
What is pleuritis?
inflammation of the pleura
lung surfaces are rough and ‘pleural rub’ can be heard with a stethescope
leads to sharp chest pain when breathing or coughing
Different surfaces of the lungs
mediastinal
diaphragmatic
costal
cervical
Mediastinal surface
flat
faces mediastinum and has impressions of mediastinal structures
contains hilum and pulmonary ligament
Diaphragmatic surface
concave and faces domes of diaphragm
Costal surface
convex and faces ribs
Cervical surface
extends into neck 2-3cm above medial third of clavicle as apex/dome/cupola
What are pleural reflections?
Line where the pleura change direction from one wall of the pleural cavity to another
When do pleural reflections occur?
When the costal pleura becomes continuous with the mediastinal pleura anteriorly and posteriorly and with the diaphragmatic pleura inferiorly
Describe the outline of the visceral pleura
Rib 2: reflections closest at plane of eternal angle
Rib 4: parallel down to rib 4
Cc 6: left indented (cardiac notch), right continues to cc6
Rib 8: crosses here at midaxillary line
Rib 10: crosses here at lateral border of erector spinae muscle
Describe the outline of the parietal pleura
Close behind rib parallel down to rib 4
Left indented (cardiac notch) but right continues down to cc 6
Rib 8 at midclavicular line
Rib 10 at midaxillary line
Rib 12 at lateral border of erector spinae muscle
Describe the lobes of the right lung
3 lobes - superior, middle, inferior
Superior and middle: mainly anterior
Inferior: mainly posterior
Describe the fissures of the right lung
Oblique fissure: from T2 posteriorly to rib 6 anteriorly
Horizontal fissure: from rib 4 to oblique fissure
Describe the lobes of the left lung
2 lobes: superior and inferior
Superior - mainly anterior and has lingual
Inferior - mainly posterior
Describe the fissures of the left lung
Oblique fissure - from T2 posteriorly to rib 6 anteriorly
Difference between right and left bronchi
Right is more vertical and wider than L
How do the main bronchi divide?
into secondary bronchi - supply lobes
then into tertiary bronchi - supply segments
How many bronchopulmonary segments does the right lung have?
10
How many bronchopulmonary segments does the left lung have?
9/10
Clinical relevance of bronchopulmonary segments
resecting a segment is preferable to resecting a lobe when there is disease
in supine ps, fluid tends to accumulate in apical and posterior segments of the inferior lobe
Describe the proximal aorta
from left ventricle
aortic arch with: 1. brachiocephalic trunk 2. left carotid artery 3. left subclavian artery
Describe the descending aorta
thoracic artery wth intercostal arteries leading off
past diaphragm: abdominal aorta
Where is the azygous system located?
posterior to the mediastinum
What is the function of the azygous system?
drainage of the posterior thoracic wall
Main veins of the azygous system
IVC, ic vein, azygous vein, SVC, left brachiocephalic vein, hemiazygous
How to view a CT scan
from the feet on their back
