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Fibrous Pericardium
-very tough and elastic
-outer layer of paricardium
-dull appearance
-protects the heart against over filling
-continuous w/ central tendon of diaphragm
Pericardial Sac
-lies posterior to the body of the sternum and 2nd-6th costal cartilages at level of T5-T8 vertebrae
-composed of two layers: Fibrous and Parietal layer of serous pericardium
Serous Pericardium
-thin membrane which secretes a serous watery fluid
-subdivided into outer parietal part and visceral layer
Outer Parietal part of Serous Pericardium
-lines inner surface of fibrous pericardium
Visceral Layer of Serous Pericardium
-also called EPICARDIUM
-reflected off fibrous pericardium onto heart itself
-outermost layer of the heart wall
What is normally in the pericardial cavity?
-some serous fluid that allows the heart to beat without much friction in the pericardial sac
Oblique pericardial sinus
-shaped like an inverted "U"
-blind cul de sac
-located up behind heart, behind left atrium which receives pulmonary veins
-bounded on right side by right pulmonary veins and IVC and on the left by the left pulmonary veins
-you can enter this sinus inferiorly with several fingers but you can't pass the fingers around any of the vessels because the sinus is a blind recess
Transverse Pericardial Sinus
-runs side to side and connects the two sides of the pericardial cavity
-lies posterior to the pulmonary trunk and ascending arota but anterior to the superior vena cava
-used by surgeons to put a ligature around the pulmonary trunk and asceding aorta during coronary bypass operations
What sinus is used to put ligature around pulmonary trunk and ascending aorta during some heart operations?
Transverse Pericardial Sinus
Where is the pericardium located?
-behind sternum and extends superiorly up to the level of sternal angle and inferiorly to the xipisternal joint
-1/3 of heart lies to right of midline
-2/3 of heart lies to left of midline
What is the fibrous pericardium fused to and what is the significance of this?
-Central tendon of diaphragm
-shape and position of heart change with each breath
-condition where serous pericardium becomes inflamed which may cause excess fluid to be secreted in the pericardial cavity
-this can cause compression of the heart which can lead to decreased circulation and incomplete filling of atria which can become deadly
Where can a pericardialcentesis be done?
-left 5th or 6th intercostal space
-can enter left part of infrasternal angle just left of xiphoid process and enter posteriorly and superiorly, angled up into the pericardium
Coronary Groove/Atrioventricular Groove
-runs around heart
-coronary vessels run through it
-separates atria and ventricles
Interventricular Groove
-perpendicular to coronary groove
-anterior part separates left and right ventricles and continues to the diaphragmatic surface of heart
-posterior part separates the two ventricles and indicates the side of the interventricular septum internally
What artery supplies the pericardium?
-mainly the pericardiacophrenic artery (branch of internal thoracic a.)
Sternal costal surface of heart
-faces ribs
-formed primarily by right ventricle but also some of left ventricle and both atria
-auricles of atria also contribute to this surface
Left/Pulmonary Surface of heart
-formed primarily by left ventricle
-this is the surface that indents the left lung and gives it the deep cardiac impression
Diaphragmatic Surface of heart
-rests on diaphragm
-formed by left and right ventricles
Base of heart
-not the diaphragmatic surface!!!!
-formed by left atrium and is the posterior aspect of the heart
-tip of heart
-formed by portion of left atrium
Long Axis of Heart
-extend from base to apex
-runs posterior to anterior
-superior to inferior
-right to left
Borders of Heart
1. Right- convex and formed by right atrium
2. Inferior- primarily by right ventricle
3. Left- primarily by left ventricle
4. Superior- line that comes across upper margins of auricles
Flow of Blood through Heart
1. SVC, IVC, coronary sinus 2. right atrium
3. tricuspid valve
4. right ventricle
5. pulmonary valve
6. pulmonary trunk, right and left pulmonary arteries
7. lungs
8. right and left pulmonary veins
9. left atrium
10. bicuspid/mitral valve
11. left ventricle
12. aortic valve
13. ascending aorta
14. arch of aorta
Right Atrium
-rough walled part and smooth walled part
-Pectinate Muscles (rough wall)
-crista terminalis
-interatrial septum
-fossa ovalis
Crista Terminalis
-smooth muscle ridge separating smooth wall from rough wall of right atrium
Pectinate Muscles
-muscular ridges in rough walled part of atria
Interatrial Septum
-divides left and right atrium
-fossa ovalis is on the right side
Right Ventricle
-tricuspid valve
-conus arteriosis/infundibulum
-pulmonary trunk
-pulmonary valve
-trabeculae carnae
-papillary muscles (anterior, posterior, septal)
-chordae tendinae
-septomarginal trabeculae/moderator band
Tricuspid valve
-separates right atrium and ventricle
What is cardiac tamponade?
-compression of the heart
-can be caused by pericarditis
Which ventricle of the heart is thickest and why?
-left ventricle (2-3 times thicker than right)
-higher systemic arterial pressure, greater than pulmonary arterial pressure
-occurs when ventricles fill with blood
Which valves are closed during diastole?
-pulmonary valve
-aortic valve
-occurs when ventricles contract and expel blood
Which valves are closed during systole?
Aortic vestibule
-smooth walled track of outvlow of blood in left ventricle
-thickening in center of each cusp of aortic and pulmonary valves
-thin margin on either side of nodule in aortic and pulmonary valves
Sinus venarum
-smooth posterior thing-walled part of adult right atrium
-formed by embryologic incorporation of part of venus sinus
-SVC, IVC, and coronary sinus open here bring poorly oxygenated blood into the heart
Sulcus terminalis
-external separation of primordial atrium and sinus venarum
3 cusps of aortic valve
3 cusps of pulmonary valve
Aortic valve
-3 cusps and sinuses (posteriro, right, left)
-obliquely placed
-mouths of left and right coronary arteries arise in left and right aortic sinuses respectively
-located posterior to left side of sternum at level of 3rd intercostal space
-best heard in 2nd intercostal space just right of sternal border
Pulmonary valve
-3 cusps and sinuses (anterior, right, left)
-located at apex of conus arteriosus at level of 3rd costal cartilage
-best heard in 2nd intercostal space just left of sternal border
Where is the tricuspid valve best heard?
-5th intercostal space near left sternal border
Where is the bicuspid valve best heard?
-5th intercostal space near apex of heart just medial to midclavicular line
Rheumatic fever
-can casue cusps of valves to become thick and stiff so they don't work properly
Which heart valve is most frequently diseased?
What are the first two branches of ascending aorta?
-left and right coronary arteries (located in left and right sinus of aortic valve/sinus
Left coronary artery
-arises from left sinus of aortic valve
-divides into 2 branches when it reaches atrioventricular groove (LAD and circumflex)
-also called anterior interventricular artery
-lies anterior to anterior interventricular groove and descends
-supplies 2/3 interventricular septum (through septal branches)
-supplies right and left bundle branches of conducting system
-runs with great cardiac vein
Why is blood supply to the conducting system to the heart so important?
-if it is compromised you get arrhythmias
Circuflex artery
-branch of left coronary artery
-passes around the left margin of the heart in the atrioventricular groove to the posterior aspect of the heart
- runs with coronary sinus
Right coronary artery
-runs in coronary groove
-3 branches: anterior right atrial, right marginal artery, posterior interventricular artery
Anterior right atrial artery
-branches off right coronary artery to supply the right atrium
-divides into SA NODAL BRANCH which supplies the SA node
Right marginal artery
-branch off right coronary artery
-passes along inferior margin of heart
Posterior interventricular artery
-branches off right coronary artery just before it terminates
-supplies 1/3 of interventricular septum
AV nodal artery
-last branch of right coronary artery
-very small
-supplies AV nodes of conducting system
what is the most frequent site of occulusion of coronary arteries?
-proximal point of LAD
Great cardiac vein
-runs with LAD
Middle cardiac vein
-runs with posterior interventricular artery
Where do most veins of the heart empty into?
-coronary sinus
Anterior cardiac veins
-drain directly into the right atrium
-cross the atrioventricular groove
SA (sinoatrial) node
-located in upper edge of cristae terminalis
-known as pacemaker
-initiates the impulse for contraction and those impulses spread throughout the left and right atriomusculature
AV (atrioventricular) node
-clump of cells located in the lower part of the interatrial septum very close to opening of coronary sinus
AV bundle
-travels along the edge of the membranous portion of the interventricular septum
-splits into right and left bundles when reaches the muscular part of the IV septum
Right bundle branch
-passes into moderator band (septal marginal trabeculae)to the anterior papillary muscle
Left bundle branch
-ramify throughout myocardium and ventricles
What controls the conducting system of the heart?
-autonomic nervous system
Cardiac plexus
-2 parts
1. superficial part
2. deep part
-consists of sympathetic, parasympathetic, and visceral afferent fibers (GVA)
-vagus nerves and sympathetic trunks contribute to the cardiac plexus
Superficial cardiac plexus
-located in concavity of the aortic arch close to ligamentum arteriosum
-anterior to aortic arch
Deep part of cardiac plexus
-located posterior to aortic arch and anterior to tracheal bifurcation
Cervicothoracic/Stellate ganglia
-fusion of inferior cervical and 1st thoracic sympathetic ganglia
Vagal parasympathetic fibers to the heart
-cell bodies of presynaptic parasympathetic neruon resides in medulla of brain stem
-synapse in cardiac plexus and wall of heart w/ postsynaptic neuron
-post synaptic neurons very short and go to innervate heart
What effect does parasympathetic stumulation have on the heart?
-slows down heart rate
-decreases force of contraction of heart
-constricts coronary arteries
What is sympathetic effect on heart?
-speeds up heart rate
-increases force of contraction
-dilates coronary arteries
Sympathetic pathway of innervation of heart
-presynaptic neurons lie in lateral horns of T1-T4
-axons leave through ventral roots of T1-T4 and go into spinal nerve
-leave spinal nerve through white ramus communicantes
-enter sympathetic trunk from T1-T4
-synapse in T1-T4 sympathetic ganglia
-post synaptic neuron leaves via thoracic cardiac branches and go to cardiac plexus
Visceral Afferent fibers of heart
-some transmit pain
-some carry cardiac reflexes
Visceral afferent cardiac pain fibers
-travel back to spinal cord w/ sympathetic fibers
-run with thoracic cardiac fibers of sympathetic trunk
-enter thoracic sympathetic ganglia via white rami communicantes and go to thoracic spinal nerve
-pain info reaches upper 4 thoracic cord segments
Cardiac reflex fibers
-travel in vagus nerve
-innervate barrow receptors that monitor blood pressure or innervate chemoreceptors which monitor oxygen content in great vessels
-cell bodies lie in sensory ganglion of vagus nerve
-if BP is too high brain will send signals via efferent fibers to slow heard down and reduce force of contraction
Where is pain of myocardial infarction often referred to?
-upper 4 thoracic dermatomes
-this is because sensory info of the skin is also entering the T1-T4 level w/ the pain visceral afferent fibers

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