Heart and Pericardium Flashcards
Describe general position of heart
In thoracic cavity
Deviated towards left side
In middle mediastinum - heart occupies most of this space
Describe boundaries of heart - all = 4
Sup = sternal angle, manubriosternal joint - t4/5, rib 2
Inferior = xiphisternal joint - level of t9
Left = left midclavicular line - lines up with apex of heart, at level of t9 (apex)
Parasternal lines = parallel, lateral borders of sternum
What is mediastinum
Compartment in thoracic cavity
What is mediastinum bounded by
1st rib
Diaphragm
Rib cage
Thoracic vertebrae
Name and explain regions of mediastinum - gen
Extrapulmonary = non lung organs, divided into 4 regions = sup and inf (ant, mid, post)
Describe superior mediastinum
Sup = Rib 1 - thoracic inlet
Inf = sternal angle, rib 2, t4/5
Describe inferior mediastinum
Sup = sternal angle, rib 2, t4/5
Inf = diaphragm
ANTERIOR, MIDDLE AND POSTERIOR MEDIASTINUM
Describe what is in middle mediastinum
Heart
Roots of great vessels
Nv
Respiratory system
Describe heart in middle mediastinum
2 serous and 1 fibrous pericardial coverings
Describe roots of great vessels in middle mediastinum
Aorta and pulmonary trunk (t junction)= away and towards heart
Arteries= right and left pulmonary arteries, biggest in body, 4 pulmonary veins
Svc = head, neck and upper limbs
Ivc = abdomen and below and lower ribs
Describe neurovasculature in middle mediastinum
INSIDE pericardium = for heart, coronary circulation and cardiac plexus
OUTSIDE pericardium =phrenic nerves and pericardiophrenic arteries and veins
Describe respiratory system in middle mediastinum
Left and right primary bronchi
What is heart enveloped by
Continuous double layer of serous membrane= pericardium
Describe pericardiums - gen
serous pericardium, encloses potential space = pericardial cavity
Has additional outer membrane = fibrous pericardium (tough ct layer, outside pericardial membrane)
Name all the layers of pericardium from superficial to deep
Fibrous pericaridum
Serous parietal pericardium
Serous visceral pericardium
Describe fibrous pericardium
Outermost
Dense ct
Anchored to roots of great vessels (pulm trunk), diaphragm and thoracic wall (sternum)
Covered in pericardial fat (above diaphragm=bottom of pericardium)
Describe serous pericardium - parietal layer
Adhered to fibrous pericardium
Deep surface- if flip = inner surface of fibrous
Hard to separate
Describe serous pericardium - visceral layer
Innermost
Shrink wraps heart
Nv visible within
Variable amounts epicardial fat - deep to serous pericardium, upon heart
What is pericardial cavity
Potential space between layers of serous pericardium
Are the visceral and parietal pericardium’s continuous
Visceral reflects and becomes continuous with parietal at where pulmonary trunk meets heart wall
Describe function of pericardial cavity and fibrous pericardium
Pericardial cavity normally contains few ml serous fluid = ease gliding of beating heart against surrounding tissues
Tough fibrous pericardium = restricts expansion of heart to help direct blood out vessels, rigid wall so when expands = helps direct blood away from heart
What is pericardial effusion
Build up of excess fluid in pericardial cavity between serous layers
May be slow = allows fibrous pericardium to stretch in response
What is cardiac tamponade
Large or rapid pericardial effusion = causes heart to accelerate to maintain volume of blood pumped despise diminishing pericardial space
Heart may stop beating - since less blood pumping = hr increase so much that heart will stop beating (decreasing space, so less blood pumped)
What is intervention to treat cardiac tamponade
Pericardiocentesis = syringe and drain space
Describe external presentation of heart
2 pumps = right and left
Each divided into 2 chambers = atrium and ventricle
Describe heart in ANATomical position
Heart rotated around longitudinal axis towards left and its inferior end (apex) tilted towards left and anterior
Describe chambers of heart and their visibilities from ant and post
Ant = see mostly right ventricle - in situ view
Post = see mainly left atrium and ventricle
Describe grooves - sulci
Muscular walls of 4 chambers of heart create sulci = shallow grooves on external surface with coronary circulation (vasculature-paired arteries and veins)
And variable fat within
Name the sulci of heart
Atrioventricular sulcus
Interventricular sulcus
Describe atrioventricular sulcus
Ring around heart between atria and ventricles = separates them
Transverse plane
Describe interventricular sulcus
Anterior = seen in anatomical position
Posterior = flips to posterior view
Between left and right ventricles, ant to post (sup to inf and back superiorly)
Describe heart - conceptual overview
Muscular organ divided into right and left pumps (Normally do not communicate in adults)
Each pump divided into 2 communicating chambers = atrium collects blood and ventricle discharges blood
Describe the 2 circuits of blood circulation
They have different roles in circulation of blood throughout body
Right pump = moves blood from heart to lungs for gas exchange = pulmonary circulation, short and nearby
Left pump = moves blood from heart to all tissues of body = systemic circulation (includes heart and bronchial circulation)
Describe cardiac blood flow = 1
Venous deoxygenated blood from systemic circulation collects into right atrium from ivc, svc, coronary sinus or directly (anterior cardiac veins) and passes into right ventricle (through valve)
Describe cardiac blood flow = 2
Deoxygenated blood then pumped from right ventricle —> pulmonary trunk/arteries and into pulmonary circulation (to lungs)= now oxygenated blood
Describe cardiac blood flow = 3
Oxygenated blood from pulmonary circulation collects in left atrium from pulmonary veins and passes into left ventricle (through valve)
Describe cardiac blood flow = 4
Oxygenated blood pumped from left ventricle —> pumped into systemic circulation through aorta and all its branches (to periphery)
Describe where right atrium collects blood from
From systemic circulation via
Svc = head, neck and upper limbs
Ivc = everything below heart
Coronary sinus = locally around heart
Which vessels/things that drain into right atrium have valves
Svc = no valve since gravity helps
Have valves to prevent back flow (passive, flaps shut in response to tendency of blood —> bc gravity to flow back)
Describe posterior atrial wall of right atrium
Where vessels enter = smooth
Describe anterior/lateral atrial wall of right atrium
Contains parallel folds of pectinate muscles, extending into right auricle
= helps expand atrial volume while minimizing atrial wall stress - to accept more of that blood coming from system
Describe how blood passes into right ventricle
Via right av valve = tricuspid
What are auricles
Left and right = blinds sacs at the end of atria = allows more blood to be collected there
What is crista terminalis
Crest at transition between smooth wall and pectinate muscle
Where is fossa ovalis
In smooth wall between the 2 atria =depression called fossa ovalis
Describe in utero - fossa ovalis
In utero = fetal lungs and pulmonary circulation are offline, bc gas exchange occurs through placenta —> prenatal circulation includes a system of shunts that allows pulmonary circulation to be bypassed
What is foramen ovale
Opening in wall between atria = allows oxygenated blood from ivc to bypass right ventricle and go into left atrium instead
What happens to foramen ovale after birth
Shortly after birth = seals over and leaves impression in atrial wall = fossa ovalis (seals, heals over due to blood pressure differences)
In 25-30% of people = foramen ovale fails to close = leads to patent foramen ovale (depends on size, can lead to oxygen insufficiency so Need surgical intervention)
Describe fetal circulation with respect to foramen ovale
Oxygenated blood comes back up from navel and umbilical vein —> ivc of developing embryo
Bit of oxygenated and deoxygenated mis
Then allows blood to be shunted from right to left atrium = bypass pulmonary trunk
Describe right ventricle
Deoxygenated blood enters right ventricle through right av valve
Describe right av valve
Has 3 cusps, linked by chordae tendinae —> 3 sets papillary muscles
3x cusps (ant, post, septal), sets of chordae, sets of papillary muscles
(Cusps —> chordae —> papillary muscles)
What is the purpose of papillary muscles and chordae tendinae
Hold onto cusps and prevent them from prolapsing into right atrium during ventricular contraction = systole
So blood wont flow back from ventricle to aorta
Prevent prolapse into atria during systole (ventricular systole)
What are trabeculae carnae
Assists ventricualr walls
Meaty struts
Pumps deoxygenated blood out the pulmonary valve (right semilunar) into pulmonary trunk
Also helps prevent walls from sticking to each other
Describe left atrium
Pulmonary veins enter here
Describe left auricle
With less pectinate muscle - smaller than right
Describe left av valve
Bicuspid, mitral valve
Only 2 sets of cusps/chordae/papillary muscles = anterior and posterior
Describe left ventricular wall
Aortic valve, left semilunar to aorta
Wall much thicker = left needs to send blood with enough pressure to reach tips of the toes - strong pump
Where is ligamentus arteriosum
At level of sternal angle
What is ductus arteriosus
Second shunt to bypass pulmonary circulation = shunts blood from pulmonary trunk to aorta
All the blood hat does make it into pulmonary trunk does not go to pulmonary arteries = bypasses
Describe what happens after birth to ductus arteriosus
First few months postnatal life = both shunts regress/disappear = ductus arteriosus —> ligamentum arteriosum
Name the 2 developmental remnants we can see in adult heart
Fossa ovalis
Ligamentum arteriosum
Name the 2 phases of cardiac cycle
Ventricular diastole
Ventricular systole
Describe ventricular diastole - gen
Longer phase
Both ventricles relax and expand in volume and bring in blood from atria
Blood refills both chambers
Describe ventricular systole - gen
Shorter phase
Both ventricles contract
Blood pumped out of them
Describe valves during ventricular diastole
Open av = blood flows into ventricles from atria, chordae tendinae not active
Closed semilunar = no blood flows back into ventricles (since ventricles, just pumped blood out)
Describe valves during ventricular systole
Open semilunar= blood flows into pulmonary trunk/aorta
Closed av = prevent back flow into atria
Describe what heart auscultation is
Listening to sound of valves closing
Valves snap shut = make audible sound that can be heart by placing stethoscope in right place = auscultation
Describe LUB sound
Closing of mitral and tricuspid valves
Louder sound
Snapping of av valves = shut in response to forceful contraction of ventricles (systole)- ventricular pressure spikes, short, powerful phase
Describe DUB sound
Closing of aortic and pulmonary semilunar valves
Shorter
Describe heart auscultation - parasternal lines
Where we can place stethoscope and heart sounds
Landmarks
Heard to hear since bone in the way so place where we can hear echo
Parasternal and midcalvicular lines
Where to hear left semilunar - aortic valve
Right 2nd intercostal space at parasternal line
Where to hear right semilunar - pulmonary valve
Left second intercostal space at parasternal line
Where to heart right av valve
Left fifth intercostal space at parasternal line
Where to heart left av valve
Left fifth intercostal space at midclavicular line
Describe coronary arteries and openings
Heart needs own blood supply
Right and left coronary arteries, first 2 branches of aorta
Openings located in sinuses created by aortic valve cusps (2 openings into coronary arteries)
When do coronary arteries fill with blood
Aortic valve sinuses and coronary arteries fill with blood when aortic valve shut = during ventricular diastole - semilunar must be shut for blood to get into coronary arteries
Offset compared to systemic blood (cardiac cycle)
Describe right coronary artery
Emerges at anterior/right base of aorta (tip of auricle), runs to the right av sulcus, around posterior surface (loops to)
Name branches of right coronary artery
Sinoatrial nodal artery
Right marginal artery
Posterior interventricular artery
Describe sinoatrial nodal artery - branch of right coronary
Runs under auricle of right atrium, loops around svc, supplies sinoatrial node and right atrium
(Sinoatrial node = pacemaker of heart)
Describe right marginal artery - branch of right coronary
Runs towards apex on right border (margin) of heart, supplies most of right ventricle
Describe posterior interventricular artery - branch of right coronary
Piva
On posterior surface, runs towards apex in posterior av sulcus, supplies posterior ventricles, and posterior 1/3 of interventricular septum (big, muscle wall)
Describe left coronary artery
Emerges at posterior/left base of aorta, runs to the left, posterior to (behind) pulmonary trunk
Name the 2 main branches of left coronary artery
Anterior interventricular artery
Circumflex artery (—> left marginal artery)
Describe anterior interventricular artery - left coronary artery
Aiva
Runs towards apex in anterior interventricular sulcus, supplied anterior ventricles and anterior 2/3 of interventricular septum
Describe circumflex artery - left coronary artery
Runs under auricle of left atrium = runs around to posterior side in av sulcus - coronary, onto posterior surface
Supplies left atrium via left marginal artery = branch of circumflex, runs towards apex on left borders (margin or heart, supplies most of left ventricle)
Name and describe the 2 important anastomoses of coronary arteries
Arterial connections, alternatives, continuous alternate connections = for blood, make sure muscle receives enough blood to function properly
Between end of right coronary and circumflex
Between piva and aiva
Describe venous drainage of heart
Cardiac veins = heart drained by network cardiac veins -paired with coronary arteries and branches, usually in sulci
Most join coronary sinus before going into right atrium
Describe coronary sinus
Swelling in av sulcus that collects venous blood from great, middle and small cardiac veins, opens into right atrium near ivc
Name the 4 cardiac veins
Great cardiac vein
Middle cardiac vein
Small Cardiac vein
Anterior cardiac veins
Describe great cardiac vein
Biggest
Runs with aiva - parallel then circumflex in left post av sulcus
Onto posterior heart —> into coronary sinus, drains anterior ventricles and left atrium
Describe middle cardaic vein
Runs with piva in post interventricular sulcus
Into coronary sinus directly
Drains posterior interventricular septum
Describe small cardiac vein
Runs with right marginal then right coronary
In av sulcus
Onto posterior heart
Into coronary sinus
Drains right atrium and ventricle
Describe anterior cardiac veins
Runs with local branches right coronary a
Very small
Opens DIRECTLY into right atrium = not coronary sinus
Drains ant right ventricle
Describe how the cardiac veins drain
Ant cardiac veins = right atrium
Great, middle and small cardiac veins = coronary sinus then right atrium
Describe innervation of heart and pericardium = sympathetic
Fibers arise from spinal cord levels t1-t4 and the cervical ganglia in neck as sympathetic cardiac nerves = cause hr to increase
Describe innervation of heart and pericardium = parasympathetic
Fibers come from vagus nerves as cardiac branches —>cause hr to decrease
Describe cardiac plexus
Sns and pans Fibers mesh to form a cardiac plexus
Providing branches to conduction system of heart, coronary vasculature and myocardium (heart muscle wall)
Name the 4 components of the hearts conduction system
Sa node
Av node
Av bundle
Purkinje Fibers
Describe sa node - conduction
Group of cells near base svc
Sends signal to another node via internodal branches
Describe av node - conduction
Near coronary sinus opening
Sits between atria and gives big bundle
Describe av bundle - conduction
Runs down av septum = gives 2 branches = right and left bundle branch
Need both to be beating at same time so both ventricles contract at same time = systole
Describe purkinje fibres - conduction
Branch to trabeculae carnae and myocardial walls
Describe septomarginal (moderator band) - conduction
Bridge across inferior right ventricle for better conductance to right anterior papillary muscles (from interventricular wall to papillary)
Shortcut so signal coming from right bundle branch can jump across to synchronize action of papillary muscle on right side, so can properly function during systole and hold on to chordae to keep the av valve closed
Describe clinical consideration - pacemaker
Sa node = Natural pacemaker of heart
Can have artificial pacemaker = pulls electrical current that sits where av or sa node normally is = Stabilized hr
Can we see nodes and bundles of conduction system
Nodes and bundles not visible = in walls of myocardium
