| Thorax | Heart | Blood | Vessels | More Heart |
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-Manubrium
-Body -Xiphoid Process (lies is epigastric fossa, used as guide in CPR) Sternal Angle in between Manubrium & Body, symphysis marked by easily palpable ridge, corresponds with 2nd costal cartilage
Describe the 3 parts of the sternum and significance of sternal angle
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During ventricular systole, the atrioventricular valves close (S1 sound) and the semilunar valves open to eject blood
During ventricular diastole, the AV valves open to fill ventricles and the semilunar valves close (S2 sound)
During ventricular systole, which of the heart valves are closed?
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Typically, the RCA supplies
-the right atrium. -most of right ventricle. -part of the left ventricle (the diaphragmatic surface). -part of the IV septum, usually the posterior third. -the SA node (in approximately 60% of people). -the AV node (in approximately 80% of people).
Which areas of the heart does the right coronary artery (RCA) supply?
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Brachiocephalic Trunk (Right Subclavian & Right Common Carotid)
2. Left Common Carotid 3. Left Subclavian
What are the 3 branches that arise off the aortic arch?
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The coronary sinus is the main vein of the heart; the heart is drained mainly by veins that empty into the coronary sinus.
Located between the right AV orifice and the IVC orifice (inside right atrium)
What is the coronary sinus and where is it located?
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3 layers: External intercostal muscle, Internal intercostal muscle, Innermost intercostal muscle
Function primarily to elevate ribs during normal quiet inspiration, can also help depress ribs in forced expiration Innervated by intercostal nerves
Name the 3 layers of skeletal muscle within the thoracic wall? What is the primary function of these 3 muscles? Which nerves innervate these muscles?
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Characteristics of Cardiac Muscle
-striated muscle -muscle fibers with actin & myosin -action potentials -1-4 nuclei -Involuntary -Autonomic Nervous System/ Pacemaker Cells -NE/AcH/Muscarinic 2 receptors -Coronary Circulation
Describe at least 3 properties of cardiac muscle
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RCA supplies the posterior 1/3 of IV septum
LCA supplies anterior 2/3 of IV septum
Describe basic blood supply to the interventricular septum
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The right and left brachiocephalic veins are formed by the union of the IJ and SC veins.
The union of the internal jugular vein and subclavian vein forms the _______________ vein?
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The fossa ovalis is a thumbprint-size depression, which is a remnant of the oval foramen and its valve in the fetus;
Site of ASD (Atrial Septal Defect) during heart development & PFO (patient foramen ovale) in adults
What is the significance of the Fossa Ovalis?
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Neurovascular structures in the intercostal space include:
VEINS, ARTERIES, NERVES (from superior to inferior, lie in costal groove) 3 intercostal muscle layers: external, internal, innermost
Describe the contents of the intercostal spaces
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1. β1-adrenoceptor
2. β2-adrenoceptors -both produce positive chronotropy, dromotropy, Inotropy, & Lusitropy 3. M2 muscarinic receptors -produce negative chronotropy, dromotropy, Inotropy, & Lusitropy
Describe the 3 receptors within the cardiomyocytes and the physiologic response when each is activated
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SVC/IVC --> RA --> Tricuspid Valve --> RV --> Pulmonary Valve --> Pulm artery/lungs --> LA --> Mitral Valve --> LV --> Aortic Valve --> Body
Describe the pathway of blood throughout the entire heart, including all valves that it passes through
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Circumflex Artery- supplies lateral side & posterior heart
Left Anterior Descending (LAD)- supplies anterior & left side
The Left Main Coronary Artery splits off into which two main arteries?
What areas of the heart do these vessels supply blood to? |
Middle mediastinum constituted by the pericardium, heart, roots of great vessels
What constitutes the middle mediastinum?
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Approximately the anterior axillary line
What area do the anterior and posterior intercostal arteries and veins converge and anastamose?
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Pericardium is a closed fibroserous sac surrounding the heart made of 2 layers: Fibrous Pericardium & Serous Pericardium
Fibrous layer- inelastic, attached to sternum (anteriorly) & diaphragm (inferiorly), helps hold heart in its middle mediastinal position and limits expansion of heart Serous layer- lines and lubricates fibrous pericardium & exterior of heart, parietal layer of serous pericardium is sensitive (phrenic nerve innervates with pain fibers)
Pericardium:
-What is it? -Describe the characteristics of each layer. |
Azygous vein
Posterior intercostal veins lead into which larger vein?
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RCA occlusion = Inferior MI
ST elevtion in leads II, III, aVF
A blockage of the Right Coronary Artery would result in which type of Myocardial Infarction and what leads would you see an abnormality in?
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Starts at SA node (junction of SVC & RA) and goes throughout both atria to contract;
AV node (near opening of coronary sinus)- delays passage of electrical impulses to ventricles which ensures atria have ejected all blood into ventricles before ventricles contract AV Bundle (Bundle of His) (IV septum)- conducts impulse towards apex of heart Purkinje Fibers- turn upward and spread signal through rest of ventricular myocardium
Briefly describe the pathway of electrical impulses through the muscle of the heart
(starting with the SA node) |
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Phrenic Nerve- derived from C3-C5
A patient develops hemi-diaphragmatic paralysis (inability to to move one side of their diaphragm) following an interscalene nerve block.... which important nerve that innervates the diaphragm was likely affected?
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The origin of the PDA (Posterior Descending Artery) determines dominance
Right dominant = PDA from right coronary Left dominant= PDA from circumflex (left) Right dominant heart better- if there is a blockage in LCA, anterior 2/3 of IV septum will be ischemic versus entire IV septum would be ischemic in left dominant heart
What determines right versus left heart dominance?
Which is better and why? |
S1- closure of AV valves- ventricular systole
S2- closure of SL valves- ventricular diastole
What is happening during each of the two normal heart sounds S1 & S2?
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Lateral infarction - Left Circumflex Artery
ST elevation in leads I, aVL, V5, V6 indicate what type of infarction? Where is the occlusion?
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If extra fluid occupies the pericardial space, the capacity of the heart to fill and pump blood may be compromised (Remember the fibrous pericarium is inelastic)
Explain why a pericardial effusion would concern you as a provider?
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