Lecture 3: Pericardium and Coronary Circulation Flashcards
What are the vertical boundaries of the mediastinum?
the parasternal lines and the left midclavicular line
What are the horizontal boundaries of the mediastinum?
the sternal angle (manubriosternal joint) and the xiphisternal joint
What is the superior limit of the mediastinum?
the sternal angle at the level of T4/T5
What is the inferior limit of the mediastinum?
the xiphisternal joint at the level of T9
What is the mediastinum?
the compartment in the thoracic cavity that holds the heart
What are the boundaries of the mediastinum?
1st rib, diaphragm, rib cage, & thoracic vertebrae
What does the mediastinum contain?
the extrapulmonary organs
What are the 5 contents of the middle mediastinum?
- heart
- great vessels (roots)
- neurovasculature inside pericardium
- neurovasculature outside pericardium
- respiratory system
What are the contents of the great vessels found in the middle mediastinum?
the aorta, pulmonary trunk and arteries (R/L), pulmonary veins, superior and inferior vena cavae
What are the contents of the neurovasculature inside the pericardium?
coronary circulation and cardiac plexus
What are the contents of the neurovasculature outside the pericardium?
phrenic nerves and pericardiacophrenic arteries and veins
What is the content of the respiratory system found in the middle mediastinum?
the primary bronchi (L/R)
What is the heart enveloped by?
the serous pericardium and pericardial cavity
What is the heart’s additional membrane called?
the fibrous pericardium (FC)
What is the fibrous pericardium made of?
dense connective tissue
What is the fibrous pericardium anchored to?
the roots of great vessels, diaphragm and thoracic wall
What can the fibrous pericardium be covered in?
pericardial fat
What are the two layers of serous pericardium called?
parietal and visceral layers
What is the parietal layer of the serous pericardium adhered to?
deep surface of fibrous pericardium
Which layer of the pericardium is hard to separate?
the parietal layer of the serous pericardium
What is the pericardial cavity?
potential space between layers of serous pericardium
What does the visceral layer of the serous pericardium do?
it ‘shrink-wraps’ the heart
What are there variable amounts of in the visceral layer of the serous pericardium?
epicardial fat
What is the order of the pericardium?
- fibrous pericardium
- serous pericardium (parietal layer)
- pericardial cavity
- serous pericardium (visceral layer)
What creates pericardial sinuses?
when the visceral serous pericardium transitions to parietal serous pericardium where the fibrous pericardium is anchored to the great vessels
What are pericardial sinuses?
cul-de-sacs within the pericardial cavity
What are the 2 pericardial sinuses called?
oblique and transverse sinus
Where is the oblique sinus found?
posterior to the heart (left ventricle/atrium)
Where is the transverse sinus found?
posterior to the aorta and pulmonary trunk
Why does the pericardial cavity only contain a few mL of serous fluid?
to ease gliding of the beating heart against surrounding tissues
Which layer of the pericardium restricts the expansion of the heart to help direct blood out the ventricles?
the tough fibrous pericardium
What is pericardial effusion?
buildup of excess fluid in the pericardial cavity that may be slow
What happens to the fibrous pericardium when there is pericardial effusion?
it stretches in response
What is cardiac tamponade?
large or rapid pericardial effusion that causes the heart to accelerate to maintain volume of blood
What can the heart do if there is a cardiac tamponade?
stop beating
What is the intervention for a cardiac tamponade?
pericardiocentesis
What are the two pumps in the heart?
the right and left pump
What are the two pumps in the heart divided into?
2 chambers
What are the 2 chambers of the heart called?
the atrium and ventricle
Where is the heart rotated around in anatomical position?
the longitudinal axis towards the left
Where is the heart’s inferior end (apex) tilted towards in anatomical position?
the left and anterior
What do the muscular walls of the four chambers of the heart create?
sulci
What are sulci?
shallow grooves on the external surface
What do sulci contain?
coronary circulation and variable fat
What is the atrioventricular sulcus?
ring around the heart between atria and ventricles
Where is the inter ventricular sulcus found?
between left and right ventricles, anterior to posterior
What provides blood supply to the heart?
the right and left coronary arteries
Where do the right and left coronary arteries come from?
the first two branches of the aorta
Where are the right and left coronary arteries located?
in sinuses created by the aortic valve cusps
When do the aortic valve sinuses and coronary arteries fill with blood?
when the aortic valve shuts (during ventricular diastole)
What happens to the coronary arteries when the aortic valve opens?
they become sealed by cusps
What happens to the coronary arteries when the aortic valve closes?
they open and fill
Where does the right coronary artery emerge?
at anterior/right base of aorta
Where does the right coronary artery run?
to the right in the atrioventricular sulcus around the posterior surface
What are the 3 main branches of the right coronary artery?
- sinoatrial nodal artery
- right marginal artery
- posterior interventricular artery
Where does the sinoatrial nodal artery run?
under auricle of right atrium and loops around superior vena cava
What does the sinoatrial nodal artery supply?
the sinoatrial node and right atrium
Where does the right marginal artery run?
towards apex on right border of the heart
What does the right marginal artery supply?
most of the right ventricle
Where does the posterior interventricular artery run?
towards apex in posterior interventricular sulcus
What does the posterior interventricular artery supply?
posterior ventricles and posterior 1/3 of inter ventricular septum (muscle wall)
Where does the left coronary artery emerge from?
posterior/left base of aorta
Where does the left coronary artery run?
to the left, posterior to pulmonary trunk
What are the 3 divisions of the left coronary artery?
- anterior interventricular artery
- circumflex artery
- left marginal artery
Where does the anterior interventricular artery run?
towards apex in anterior interventricular sulcus
What does the anterior interventricular artery supply?
anterior ventricles and 2/3 of interventricular septum
Where does the circumflex artery run?
under auricle of left atrium, in atrioventricular sulcus, onto posterior surface
What does the circumflex artery supply?
left atrium and via #6
Where does the left marginal artery run?
towards apex on the margin of the heart
What does the left marginal artery supply?
most of the left ventricle
What artery is a branch of the circumflex artery?
the left marginal artery
Which two anastomoses are formed in the common coronary artery configuration?
- between end of right coronary and circumflex arteries
- between anterior and posterior interventricular arteries
What is heart dominance?
it describes which coronary artery gives rise to the posterior interventricular artery
Why is heart dominance important?
because it determines the posterior third of the interventricular septum
What is right dominant composed of?
70% posterior interventricular artery from right coronary artery
What is left dominant composed of?
15% posterior interventricular artery from left coronary artery and circumflex artery
What is codominant composed of?
15% posterior interventricular artery from both
What is atherosclerosis?
when plaque deposits build up on internal walls of coronary arteries
What is the consequence of atherosclerosis?
stenosis
What is stenosis?
narrowing of lumen
What causes myocardium?
local ischema of heart muscle
What is myocardial infarct?
tissue necrosis
What are the stages of myocardial infarct?
atherosclerosis -> stenosis -> myocardium -> myocardial infarct
What can less severe blockages be treated by?
angioplasty
What is an angioplasty?
percutaneous coronary intervention
What do severe blockages require?
coronary artery bypass graft
What do coronary artery bypass grafts do?
they circumvent the blockage and restore blood flow
Why is it important to know cardiac dominance?
because if blockage is in proximal LCA, then PIVA may be affected, but less so in codominant hearts
What are the 4 cardiac veins?
- great cardiac vein
- middle cardiac vein
- small cardiac vein
- anterior cardiac veins
What are the cardiac veins paired with?
coronary arteries
Where are the cardiac veins paired with the arteries?
in the sulci
Which artery runs with the great cardiac vein?
the anterior interventricular artery
What does the great cardiac vein drain?
anterior ventricles and left atrium
Which artery runs with the middle cardiac vein?
the posterior interventricular artery
What does the middle cardiac vein drain?
posterior interventricular septum
Which artery runs with the small cardiac vein?
the right marginal artery and right coronary artery
What does the small cardiac vein drain?
right atrium and ventricle
Which artery runs with the anterior cardiac veins?
local branches of right coronary artery
What do the anterior cardiac veins drain?
the anterior right ventricle
What is special about the anterior cardiac veins?
they drain directly into the right atrium
What is the coronary sinus?
swelling in atrioventricular sulcus that collects venous blood form great, middle and small cardiac veins
What does the coronary sinus open into?
the right atrium near the inferior vena cava
