Pericardial Sac and Heart Flashcards
What is the mediastinum? Name and delineate the four subdivisions of the mediastinum.
The mediastinum is the middle region between the two pleural sacs.
The four subdivisions are the middle, superior, posterior and anterior.
Describe the make-up of the pericardial sac?
- outer fibrous layer which is fatty and blends with the central tendon of the diaphragm
- inner serous layer with the parietal and visceral components
Describe the relationships of the pericardial sac to the heart? To the vessels? to the diaphragm? lungs?
the visceral layer is reflected directly on to the heart and the roots of the great vessels.
the fatty fibrous pericardium blends with the central tendon of the diaphragm
Describe the transverse sinus.
It’s the sinus created by the folding of the primitive heart tube at the base of the great vessels - located behind the aorta and pulmonary trunk
clamped during surgery to stop blood flow from the heart
Describe the oblique sinus.
Blind culdesac sinus behind the heart
Identify the blood supply to the pericardium?
The fibrous pericardium is supplied by the pericardiacophrenic arteries
The serous visceral pericardium is supplied by the coronary arteries
Describe the nerve supply to the pericardium?
The fibrous pericardium is innervated by the phrenic nerves
the serous visceral pericardium is innervated by the coronary plexus
Where and why is pericardial pain referred?
radiates from the substernal region and left pectoral region to the left shoulder and arm. This occurs because ischemia stimualtes nerve endings that run centrally in the cardiac branches of the sympathetic trunk and enter the spinal cord at segments T1-T5 on the left side. Cutaneous fibers from these levels go to the left shoulder and arm.
Name the atrioventricular and arterial valves of the heart.
atriventricular vavles: tricuspid and mitral
arterial valves: aortic semilunar and pulmonary semilunar
Locate the approximate site on the anterior thoracic wall where the sounds of each valve can best be auscultated.
mitral valve - superficial to the apex beat at the left 5th intercostal space
aortic valve - 2nd righ intercostal space at the edge of the sternum
tricuspid valve - left lower end of the sternum
pulmonary valve - 2nd left intercostal space just to the left of the sternum
Describe the path of blood thorugh the heart.
1
Describe the INTRINSIC conduction system of the heart.
The SA node, AV node, bundle of His and purkinje fibers
Describe the extrinsic nerve supply to the heart - both sympathetic and parasympathetic.
sympathetic: arise from the sympathetic trunk in the upper thoracic and cervical regions - increase rate and force of contraction, also carry pain sensation
parasympathetic: originate from the vagus nerve and synapse on ganglia in the wall of the heart - slow the rate and force of contraction
What is contained by the middle mediastinum?
it contains the pericardium, heart and roots of the great vessels within the pericarial sac
What is contained by the superior mediastinum?
the great veins, aorta and branches, part of the trachea, esophagus, vagus nerve, recurrnet laryngeal nerves, thoracic duct and thymus.
What is contained in the anterior mediastinum?
thymus gland (anterior to the fibrous pericardium and posterior to the sternum)
WHat is contained in the posterior mediastinum?
contains a continuation of many structures contained in the superior mediastinum - esophagus, descending aorta, and thoracic duct
What are the three openings in the right atrium?
superior vena cava
inferior vena cava
coronary sinus
What valve protects the communication between the right atrium and the right vetnricle/
the right atrioventricular orifice = tricuspid valve
WHat are the three cusps of the tricuspid valve?
septal, posterior and anterior
What attaches the tricuspid cusps to the papillary muscles?
chordae tendinae
What is the function of the papillary muscles?
when the ventrile contracts, the papillary muscles contract and prevent the cusps from being forced into the atrium by pulling on the chordae tendineae
What valve protects the pulmonary orifice (the communication between the right ventircle and the pulmonary trunk)?
the pulmonary valve (semilunar valve)
How many cusps are involved in the semilunar valves?
3 - anterior, right and left
What happens to the semilunar valve cusps during systole?Diastole?
systole = the cusps are pushed against the wall of the pulmonary trunk of the out-rushing of blood
diastole - blood flows back towards the heart and fills the sinuses to close the orifice and allows the ventricles to fill
The pectinate muscles are located along the anterior wall of the atria. What is the equivalent in the ventricles?
the trabeculae carneae
Why is the moderator band (septomarginal trabeculae) so important?
It conveys a part of the conducting system to the papillary muscles, so they know when to pull the AV valve closed
The left atrium has openings of the four…
pulmonary veins
What valve separates the left ventricle from the left atrium?
the mitral valve or bicuspid valve
WHat are the two cusps of the mitral valve?
the atnerior and posterior
What valve guards the aortic orifice?
the aortic semilunar valve
Behind each cusp, the aorta bulges to form what? What blood vessels arise this area?
the aortic sinus - the right and left coronary arteries originate from this area
What representes the sole conduction connection between the atria and the ventricles?
the bundle of HIS (AV bundle divides innto left and right bundle branches)
What defines coronary artery dominance?
by which coronary artery gives off the posterior interventricular artery - most are right dominant
Where does the left coronary artery arise from? How about the right?
left aortic sinus
right aortic sinus
What are the two main branches of the left coronary artery (usually)?
anterior interventricular branch = left anterior descending (LAD)
Circumflex branch
What are the branches of the right coronary artery (usually)?
right marginal branch
posterior interventricular artery
SA Nodal artery
What does the left coronary artery supply?
interventricular septum and both ventricles
left artium and left surface of the heart
may help to supply the SA node
WHat does the right coronary artery supply?
right atrium and right ventricle
SA node
AV node and AV bundle
Which is more commonly occluded - the RCA or the LCA?
LCA
Where do most of the cardiac veins drain into?
the coronary sinus
What does the coronary sinus open into?
the right atrium
What are the main veins of the heart?
great cardiac vein middle cardiac vein small cardiac vein oblique vein of the L atrium posterior vein of the left ventricle
THe smallest veins of the heart drain into where?
directly into the chambers of the heart
Why are the coronary arteries called funcitonal end arteries?
Because their anastomoses are anatomical but no physiological - so only SLOWLY progressing occlusions stimulate formation of new collateral - acute occlusion is devastating because there’s no redundancy in the blood supply
What is the main symptoms of progressive coronary atherosclerosis?
angina pectoris
What is heart block?
When the conduction system is disrupted by occlusion of blood flow
During paracentises of the pericardium, where do we put the needle/
through the 5th or 6th intercostal space near the sternum
What is cardiac tamponade?
compression of the heart that occurs because of accumulation of fluid around the heart, interfering with filling
