Lesson 2 Flashcards
The posterior region of the right atrium is made up of a smooth wall, referred to as what?
Sinus venorum
The anterior part of the right atrium is lined by parallel muscle bundles known as what?
Pectinate muscles
The medial region of the right atrium is made up of the?
Interatrial septum
Which structures lead to or are found in the sinus venorum?
- SVC
- IVC
- Coronary sinus
- fossa ovalis
- sinoatrial (SA) node
- atrioventricular (AV) node
What is the significance of the crista terminalis?
The sulcus terminalis corresponds to the crista
terminalis on the inner surface of the heart.
Where is the sulcus terminalis?
Externally, on the posterior surface is a groove called the sulcus terminalis and extends
vertically, from the superior vena cava to the inferior vena cava. The intersection of the
sulcus terminalis, lateral border of the SVC, and superior border of the right auricle, is used
to approximate the location of the SA-node.
Where is the superior
cavoatrial junction?
The point where the SVC meets the sinus venorum,
The inferior vena cava is guarded by a valve known as, what?
Eustachian valve
The coronary sinus is guarded by what valve?
Thebesian valve
What does the eustachian ridge separate?
The opening of the inferior
vena cava and coronary sinus.
The muscular rim surrounding the tricuspid orifice is called
what?
Vestibule or supravalvular lamina
Between the IVC and tricuspid valve is a quadrilateral region
known as what?
Cavotricuspid isthmus
What is the tendon of Todaro?
Tendinous structure
which connects the eustachian valve to the right fibrous trigone of the cardiac skeleton; the boundary between the fossa ovalis and coronary sinus.
What are Thebesian veins?
The floor of the right atrium and surface of the atrial septum are covered in these numerous tiny
cardiac veins. These veins drain deoxygenated blood from the
cardiac musculature directly into the right atrium.
What and where is the Triangle of Koch?
- Located on the floor of the right atrium
- an important landmark because it is the
location of the AV-node - The Triangle of Koch is made up of (1) the opening of the coronary sinus, (2) the anterior portion of the tricuspid valve annulus, (3) and the Tendon of Todaro
What are the three components of the right ventricle?
- The inlet or inflow tract - the inlet is made up of the tricuspid opening, where blood passes through from the right atrium and into the right ventricle.
- The outlet or outflow tract - outflow tract is the passage to the pulmonary artery. It has a smooth wall and is referred to
as the infundibulum or conus arteriosus; the tricuspid valve and pulmonary valve are
separated by a muscular structure called the crista supraventricularis - The apical component.
On the apical component of the right ventricle, the anterior wall or inferior wall is lined by muscle bundles called
what?
Trabeculae carneae or Trabeculae cordis
What is the the moderator band or septomarginal trabecula?
- On the lower ventricular septum, toward the anterior wall
- muscle joins the anterior papillary muscle to the
ventricular septum - moderator band has a portion of the right bundle branch within it and conducts impulses from the ventricular septum to endocardium of the right ventricle
What is the chordae tendineae?
Chordae tendineae are attached to the AV-valves, which prevent its leaflets from collapsing back into the atrium during contraction and causing valvular regurgitation
What are the papillary muscles?
The chordae tendineae are
attached to papillary muscles, which project from the trabeculae carneae. The papillary muscles pull down on the chordae tendineae.
The left atrium is made up of what 3 components?
- the appendages - lined with pectinate muscles, walls of the left atrium are mostly smooth
- vestibule - located between the
inferior pulmonary vein and mitral annulus and is called the left atrial isthmus - venous components
The left ventricle is made up of what three components?
- The inlet refers to the opening of the mitral valve. The inflow tract is funnel-shaped, and is
formed by the mitral annulus, mitral valve leaflets, and their chordae tendineae. - The outlet or outflow tract refers to the opening of the aorta and is surrounded by smooth wall.
- The apical component of the left ventricle is also made up of trabeculae carneae.
What is the SA node?
- the natural pacemaker of the heart
- located at the roof of the right
atrium, within the crista terminalis - responsible for the organized and regular beating of
the heart - heart rates originating from the SA-node are 60–100 beats per minute (bpm).
What are the Internodal Pathways?
- Bachmann’s Bundle – Anterior tract that directs impulses from the SAN to both the
left atrium and AVN - Wenckebach’s Bundle – Middle tract that directs impulses from the SAN to AVN
- Thorel’s Bundle – Posterior tract that directs impulses from the SAN to AVN
What is the AV node?
- located in the right atrium, within the triangle of Koch
- main function of
the AV-node is to slow down electrical impulses coming from the SA-node. Slowing down
the electrical impulses is necessary to allow the ventricles time to fill with blood during atrial contraction. - Heart rates originating from the AV-node are 40-60 bpm, and the AV-node can serve as the latent pacemaker if the SA-node malfunctions.
What is the Bundle of His?
The bundle of His transmits electrical impulses from the AV-node and passes through the
cardiac skeleton before dividing into the left and right bundle branches.
What are the Bundle Branches?
The bundle branches are made up of the right and left bundle branches. The left bundle
branch is further divided into the left anterior fascicle and left posterior fascicle. Unlike the
left bundle branch, the right bundle branch is insulated and corresponds to the moderator
band. The bundle branches travel down the interventricular septum, directing themselves to
their respective ventricles to conduct electrical impulses toward the Purkinje fibers.
What are Purkinje Fibers?
These fine, small fibers penetrate the myocardium and spread electrical impulses for
contraction. Heart rates originating from the Purkinje fibers are 20-40 bpm.
