ANATOMY of the heart Flashcards
What are the features of the thorax?
Superior thoracic aperture
Inferior thoracic aperture
Thoracic wall
The thoracic cavity contains?
- Two pleural cavities
- The mediastinum
On average a heart pumps?
5/6 L blood/min
Location of the heart
5th Intercostal midclavicular line
What is the Pericaridium
Specialised double walled sac that contains :
- heart
- roots
- great vessels
Functions of pericardium
• Confines the heart to the middle of the inferior mediastinum
• Allows sufficient free movement
• Provides lubrication between the external
surface of the heart and the inner
pericardial layer
• Prevents excessive dilation of the heart
• Protects from infection
The pericardium is anchored in place superiority ?
Superiorly by the great vessels – it is continuous with the adventitia layer of the great vessels
The pericardium is anchored in place anteriorly?
Anteriorly by sterno-pericardial ligaments which attach to the posterior surface of the sternum
The pericardium is anchored posteriorly ?
Posteriorly by loose connective tissue to structures in the posterior mediastinum
The pericardium is anchored inferiority?
Inferiorly by the central tendon of the diaphragm
What are the layers of the Pericardium?
Fibrous pericardium
Serous pericardium
Layers of serous pericardium
Parietal serous pericardium
Visceral serous pericardium
What is the fibrous pericardium ?
The tough conical outermost layer, whose apex is pierced by the aorta, pulmonary trunk and SVC. Dull in appearance.
What is the pericardial cavity ?
Potential space between parietal and visceral serous pericardium.
CONTAINS PERICARDIAL FLUID
What is the Parietal serous pericardium?
Lines inner surface of the fibrous pericardium
What is the Visceral pericardium?
Aka EPICARDIUM
lines the surface of the heart
Nerve supply of Fibrous layer of pericardium
Phrenic- main sensory and motor supply
Vagus nerve (CN X) and sympathetic nerves
Nerve supply of Parietal layer of Serious Pericardium
Phrenic main sensory and motor supply
Vagus (CN X) and sympathetic nerves
Which layer of the Serous pericardium is insensate- not perceived by senses?
Visceral
Arterial supply of Pericardium
- Pericardiophrenic & musculophrenic arteries
Main supply - Pericardial arteries - supply dorsal pericardium
- Coronary arteries - supply epicardium
Main blood supply of pericardium
Pericardiacophrenic & musculophrenic arteries
From internal thoracic artery
From subclavian
Blood supply to dorsal pericardium
Pericardial arteries
From bronchial, oesophageal and superior phrenic arteries
From thoracic aorta
Blood supply to epicardium
Coronary arteries
Explain venous supply of pericardium
Veins of pericardium enter at :
- Accessory hemiazygos vein
- internal thoracic vein - pericardiophrenic veins
- hemiazygos vein
- azygos vein
What are the borders of the heart In a standard postero-anterior (PA) view on a chest radiograph?
Right border = SVC, RA, IVC
Left border = The arch of the aorta,
pulmonary trunk, left auricle, LV
Inferior border = RV, LV at the apex
Coronary sulcus contains
Right coronary artery
Small cardiac vein
Coronary sinus
Left circumflex artery
What is the Coronary sulcus?
Separates atria and ventricles
What is the Anterior interventricular sulcus?
Anteriori partition between ventricles
Anterior interventricular sulcus contains?
Anterior interventricular artery
Great cardiac vein
What is the Posterior interventricular sulcus?
Posterior partition between ventricles
Posterior interventricular sulcus contains
Posterior interventricular artery
Middle cardiac vein
Layers of heart
Epicardium - outermost
Myocardium - muscular
Endocardium - thin inner layer
Which layer of the heart contains myocytes?
A- epicardium
B- myocardium
C- endocardium
B
Myocardium
Features of Epicardial fat
- Lies between the epicardium (visceral pericardium and the myocardium of the heart
- Accumulates around the coronary arteries
- increased amounts are associated with CVD; atherosclerosis and obesity
Chambers of the Heart
Right atrium
Right ventricle
Left atrium
Left ventricle
Features of Right Atrium
Forms right border/ a portion of the heart’s anterior surface
The SVC, IVC and coronary sinus all return deoxygenated blood to the RA.
This blood enters the RV through the right AV orifice, (location of the tricuspid valve)
What is the muscular ridge that internally in the right atrium?
Crista terminalis - divides sinus of venar from atrium proper
What is the muscular ridge of the right atrium called externally?
Sulcus terminal is
The fossa oval is is a remnant of the ?
Foramen ovale - connects the atria in the fetal circulation
At what depression does the fossa oval is exist?
At the level of the inter atrial septum ( separates left atrium and right atrium)
Which structure forms right border - anteriori surface of heart ?
Right atrium
Which structure form most of the heart’s anterior surface and some of the diaphragmatic surface?
Right ventricle
How does blood Exeter the right ventricle?
From the RA through the tricuspid valve in a HORIZONTAL FORWARD DIRECTION
Key features of Right Ventricle
- Inflow portion (conus arteriosus)
Smooth-walled and located on the superior aspect of the ventricle, near the opening to the pulmonary artery - Outflow portion
Walls contain irregular muscular columns (trabeculae carnae) - increases the heart’s mechanical and conductive performance
Types of Trabeculae Carnae
- Ridges
- Bridges
- Pillars
Contraction of which muscles prevents prolapse/ eversion of cusps intro atria during systole?
Papillary muscles attached to AV valve
Example of Bridges?
Moderator band
Example of pillars in Trabeculae carnae
Papillary muscles - attach to tricuspid valve via cusps via chordate tendinae
The left atria forms?
The base of the heart
The left atrium receives blood from ?
Pulmonary vein through mistrial valve, to LV
Fractures of Left Atrium compared to RA?
Also has a (left) auricle
Interior surface consists of a smooth inflow portion, and a more rugged outflow portion (lined by pectinate muscle)
NO CRISTA TERMINALIS
Location of Left ventricle in situ
Contributes to the anterior, diaphragmatic, and left pulmonary surfaces of the heart, and forms the apex
Features of LV compared to RV
CHAMBER IS LONGWR
MYOCARDIUM IS THICKER
Trabecular carneae: Finer and more delicate
NUMBER OF PAPILLARY MUSCLES : Has TWO (rather than three) attaching to the cusps of the mitral (rather than tricuspid) valve leaflets
Size of PAPILLLARY MUSCLES: Those in LV are LARGER
NO MODERATOR BAND:
Blood enters ascending aorta through aortic valve (rather than pulmonary trunk through pulmonary valve)
What are semilunar valves?
Aortic and pulmonary valves
Each valve has 3 crescent-shaped cusps
OPEN»_space; Lets blood enter the pulmonary and
systemic circulations
CLOSE»_space; Prevents back flow of blood from the
pulmonary trunk/aorta into the RV/LV
Closure of which valves creates the sound DUB
Semi-lunar valves
Do semilunar valves contain chordae tendinae?
No
Function like valves in veins
The heart has a dense fibrous (cardiac) skeleton comprised of 4 connective tissue rings, which are?
- Fibrous ring of pulmonary valve
- Fibrous ring of aortic valve
- Right atrioventricular ring
- Left atrioventricular Ring
Describe adult circulation
- SVC from systemic circulation
- RA
- RV via tricuspid valve
- Pulmonary arteries via pulmonary valve
- Lungs to get oxygenated
- Pulmonary veins from pulmonary circulation
- LA
- LV via biscuspid / mitriai valve
- Aorta via aortic valve
- Aorta to systemic circulation
Collectively the right side of the heart in adults is the ?
Pulmonary circuit
Collectively the left side of the heart is the?
Systemic circuit
What are the 3 vascular shunts in fetal circulation?
- Foramen ovale
- Ductus arteriosus
- Ductus venosus
Where us the Foramen ovale in the fetal circulation?
Between the atria. Blood bypasses the pulmonary circulation.
Where is the Ductus arteriosus?
Links the distal arch of aorta with the pulmonary trunk.
Blood bypasses the pulmonary circulation.
Where is the Ductus venosus?
Shunts 30% of umbilical blood from the primitive liver, to the IVC to ensure enough oxygen reaches the developing brain
Why does the fetal circulation have three vascular shunts ?
To allow blood to bypass the liver and non-functioning lungs
How does the Foramen ovale close in the fetal circulation?
A baby’s first breath causes a decrease in pulmonary vasculature resistance, which increases the relative pressure in the LA > RA and causes the foramen ovale to close
How do the ductus arteriosus and venosus close in fetal circulation?
Increased O2 concentration within the blood leads to decreased prostaglandins (bradykinin), causing the walls of the ductus arteriosus and venosus to contract and close.
What vessels supply oxygenated blood to the myocardium?
Right Cronary Artery and Left Coronary Artery
RCA & LCA
RCA and LCA arise from?
Aorta at the aortic sinuses, just above the aortic valve
RCA and LCA reside?
In the CORONARY SULCUS
LCA arises from?
Left aortic sinus of th ascending aorta
Branches of LCA
- Anterior interventricular artery (left anterior descending – LAD)
- Circumflex (LCx) artery
Function of fibrous skeleton (cardiac) in heart
Maintain shape & support
Attachment site for valves & myocardium
Electrical insulation
What is the anterior interventricular artery (left anterior descending - LAD)
Travels towards apex in the anterior interventricular sulcus.
Sometimes gives off diagonal branches
What is the Circumflex artery
Courses left in the coronary sulcus onto the base/diaphragmatic surface of the heart.
The left marginal artery usually arises from the LCx and travels along the obtuse margin of the heart
Branches of RCA
- Atrial branch
- Right marginal branch
- Atrio-ventricular branch
- Posterior interventricular branch
Describe Atrial branch
Between the right auricle and ascending aorta.
Gives off sinu-atrial nodal branch (which supplies the SAN)
Describe Right marginal branch
Travels from the heart’s inferior margin towards the apex
Describe Atrio-ventricular branch
Small branch supplying AV Node
Describe Posterior interventricular branch
Comes from RCA as it travels along the diaphragmatic surface/ base of the heart.
Lies in the posterior interventricular sulcus
RCA supplies ?
RA and RV
Right marginal artery supplies ?
RV and Apex
Left marginal artery supplies ?
LV
Left anterior descending artery supplies?
RV, LV and Interventricular septum
Left circumflex artery supplies?
LA and LV
Explain Coronary dominance
Determined by origin of posterior descending artery (PDA), which supplies the posterior 1/3 of the interventricular septum
SA and AV nodes are supplied by?
RCA in 69% and 90 % of cases respectively
NB: The circumflex branch of the LCA sometimes supplies these structures instead.
What is the coronary sinus?
Large venous structure located in the coronary sulcus on the posterior surface of the heart
Coronary sinus collects and empties venous blood from?
Great, middle, small and posterior cardiac veins directly into the right atrium
Coronary veins
- Great cardiac ( anterior interventricular) vein
- Middle cardia (posterior interventricular) vein
- Posterior cardiac vein
- Small cardiac vein
- Anterior cardiac veins
- Smallest cardiac veins
Begins at the apex of the heart
Ascends in the anterior interventricular sulcus alongside the anterior interventricular artery (LAD) Continues onto the base/diaphragmatic surface of the heart, where it travels in the coronary sulcus alongside the circumflex branch of the LCA
It gradually enlarges to form the coronary sinus
Which vein is that?
Great cardiac (anterior interventricular) vein
Begins at the apex of the heart
Ascends in the posterior interventricular sulcus alongside the posterior interventricular artery (PDA) towards the coronary sinus
Which vein is that ?
Middle cardiac (posterior interventricular) vein
Lies on the posterior surface of the LV just to the left of the middle cardiac vein
It either enters the coronary sinus directly or joins the great cardiac vein
Which vein is that?
Posterior cardiac vein
Lies on the posterior surface of the LV just to the left of the middle cardiac vein
It either enters the coronary sinus directly or joins the great cardiac vein
Which vein is that?
Small cardiac vein
Arise on the anterior surface of the RV, cross the coronary sulcus and enter the anterior wall of the RA
Which vein is that?
Anterior cardiac veins
Drain directly into the cardiac chambers. Most numerous in the RA and RV
Which vein is that ?
Smallest cardiac veins
What nodes and networks initiate and coordinate contraction ?
SA NODE
AV NODE
AV BUNDLE (left and right branches)
PURKINJE FIBRES
Features of SA node
- Cardiac pacemaker
* Located in the right atrium near the SVC entrance
Features of AV node
- Located near opening of coronary sinus
* Demarks the beginning of AV bundle
Features of AV bundles
• Travels along the interventricular septum before forming R and L bundle branches, which travel towards the apex
• NB - The right bundle branch enters the septo-marginal trabecula to reach the anterior papillary muscle before
dividing into Purkinje fibres – smaller terminal branches which spread excitation impulses through the ventricles
Key features of cardiac conduction system
- Unilateral pathway of excitation/contraction
- Co-ordinated myocardial contraction - Large conduction branches are insulated
- Decreasing inappropriate stimulation
of myocardial tissue
Cardiac conduction is initiated where ?
Sinoatrial node - SAN
What regulates heart rate, force of contraction and cardiac output ?
Autonomic nervous system = sympathetic and parasympathetic
Via cardiac plexus
How is the desired innervation effect reached in the heart?
Branches of mixed nerves supplying the heart via the cardiac plexus affect the conduction system, coronary blood vessels, and atrial and ventricular musculature to achieve their desired effect
Explain sympathetic innervation of the heart
Sympathetic chain: T1 – T4, sometimes T5 too
→ cervical cardiac & thoracic cardiac nerves
- cardiac plexus
→ branches to the SA & AV nodes & directly to myocardium
= ↑ rate & force of contraction
Explain Parasympathetic innervation
Sympathetic chain: T1 – T4, sometimes T5 too
→ cervical cardiac & thoracic cardiac nerves
- cardiac plexus
→ branches to the SA & AV nodes & directly to myocardium
= ↓ rate & force of contraction
Explain Visceral innervation
Afferent fibres pass through cardiac plexus and return to CNS via sympathetic trunk and vagal cardiac branches
= Alterations in BP and blood chemistry
Why does Referred pain occurs?
Referred pain occurs because the brain cannot distinguish between sensory input from visceral sensory neurons within the ANS (supplying heart) and spinal nerves from the somatic nervous system (supplying skin sensation)
What is the angle of Louis ?
Sternal angle
Listen 2nd ICS, right sternal border for?
Aortic valve
Listen 2nd ICS, left sternal border for?
Pulmonary valve
Listen 5th ICS, mid-clavicular line (APEX) for?
Mitral valve
Listen 4th ICS, right sternal border for?
Tricuspid valve
The left atrium and ventricle drain into?
RIGHT jugulo-subclavian junction
The right atrium and ventricle drain into?
The LEFT jugulo-subclavian junction
AP imaging of the heart
Heart appears enlarged (cardiomegaly) and heart details are difficult to visualise Mediastinum appears widened
PA imaging of the heart
Heart is not magnified and markings are well delineated
Mediastinum is not widened
What is a Coronary Angiogram?
Method of visualising blood flow through the coronary arteries
A radio-opaque contrast (dye) is injected into the blood vessel (using a catheter) and XR images are taken to see how the dye moves through the artery
What is a Percutaneous Coronary Intervention (coronary angioplasty)?
Involves using a balloon to widen a stenosed or occluded artery. A stent is left in place to prevent recurrence
How is Myocardial Infarction (MI) developed?
Occlusion»_space; Reduced blood (and oxygen) supply to myocardium»_space; myocardial necrosis
Uses of Cardiac CT
Evaluation of coronary arteries
Presence of cardiac masses
Aortic abnormalities
- e.g. aortic dissection
Pericardial disease
- e.g. pericarditis
Uses of MRI in the heart?
To assess heart perfusion, for scarring, anatomic defects or masses. Can also assess the function of cardiac chambers and valves
