hi let's talk about the right atrium in this  video we'll discuss the unique structures of  
hi let's talk about the right atrium in this  video we'll discuss the unique structures of  

the right atrium the right atrium as you recall  is the recipient of all of the blood coming back  
the right atrium the right atrium as you recall  is the recipient of all of the blood coming back  

from systemic circulation so it's going to  receive blood from the superior vena cava  
from systemic circulation so it's going to  receive blood from the superior vena cava  

the inferior vena cava and the coronary sinus  which is serving the heart the region into  
the inferior vena cava and the coronary sinus  which is serving the heart the region into  

which these vessels drain is called the sinus  venarum and it's very smooth-walled so we can  
which these vessels drain is called the sinus  venarum and it's very smooth-walled so we can  

see precisely how smooth-walled this is along  these sides not rugos at all we can contrast that  
see precisely how smooth-walled this is along  these sides not rugos at all we can contrast that  

from the anterior portion of the atria which has  ridges in it these ridges are pectinate muscles so  
from the anterior portion of the atria which has  ridges in it these ridges are pectinate muscles so  

the myocardium is pushing the endocardium inward  to form these ridges and this region is separated  
the myocardium is pushing the endocardium inward  to form these ridges and this region is separated  

from the sinus venarum by the crista terminalis  so if we were to kind of move that flap back  
from the sinus venarum by the crista terminalis  so if we were to kind of move that flap back  

we would see that the crystal terminalis is  running right around there at the superior  
we would see that the crystal terminalis is  running right around there at the superior  

margin of the crista terminalis there is  a collection of specialized cardiomyocytes  
margin of the crista terminalis there is  a collection of specialized cardiomyocytes  

called the sinoatrial node or the sa node this  is known as the pacemaker region of the heart  
called the sinoatrial node or the sa node this  is known as the pacemaker region of the heart  

and it's what the cardiac plexuses are  going to work upon to alter heart rate
and it's what the cardiac plexuses are  going to work upon to alter heart rate

now between this the right and deep to this the  left atrium there is an inter atrial septum or  
now between this the right and deep to this the  left atrium there is an inter atrial septum or  

a wall that divides the two atria and we can see  here and here there is a very fragile or thin part  
a wall that divides the two atria and we can see  here and here there is a very fragile or thin part  

to that septum called the fossa ovalis the fossa  ovalis is a remnant of a fetal structure called  
to that septum called the fossa ovalis the fossa  ovalis is a remnant of a fetal structure called  

the foramen ovale where there were two septa and  a patency between them that space between them  
the foramen ovale where there were two septa and  a patency between them that space between them  

is called the foramen ovale and it represents  a pathway of blood that in utero can go from  
is called the foramen ovale and it represents  a pathway of blood that in utero can go from  

the inferior vena cava through the right atrium  to the left atrium and then out through the left  
the inferior vena cava through the right atrium  to the left atrium and then out through the left  

ventricle aortic valve so it shortcuts  pulmonary circulation there's no need to send  
ventricle aortic valve so it shortcuts  pulmonary circulation there's no need to send  

oxygen-rich blood to the lungs because the  lungs aren't serving as an organ of respiration  
oxygen-rich blood to the lungs because the  lungs aren't serving as an organ of respiration  

at that point we can see there's a there's  a ridge here and that ridge corresponds to  
at that point we can see there's a there's  a ridge here and that ridge corresponds to  

the division between the right atrium and the  right ventricle so the tricuspid valve is going  
the division between the right atrium and the  right ventricle so the tricuspid valve is going  

to be anchored within that ridge but we can also  see the opening to the coronary sinus should be  
to be anchored within that ridge but we can also  see the opening to the coronary sinus should be  

there there's the ridge the opening would be  approximately there and just superior to that  
there there's the ridge the opening would be  approximately there and just superior to that  

kind of at the nexus of the atrioventricular  septum and the interatrial septum we have another  
kind of at the nexus of the atrioventricular  septum and the interatrial septum we have another  

collection of specialized cardiomyocytes called  the atrioventricular node or the av node for  
collection of specialized cardiomyocytes called  the atrioventricular node or the av node for  

short that av node is going to be a coordination  center for the depolarization of cardiomyocytes  
short that av node is going to be a coordination  center for the depolarization of cardiomyocytes  

as they transcend that atrioventricular  septum or the fibrous skeleton of the heart
as they transcend that atrioventricular  septum or the fibrous skeleton of the heart

now here is a view of the atria with the walls  of the atria removed as well as that septum so  
now here is a view of the atria with the walls  of the atria removed as well as that septum so  

there would be the interatrial septum and we  can see the orifice for the tricuspid valve that  
there would be the interatrial septum and we  can see the orifice for the tricuspid valve that  

tricuspid valve gets its name as tricuspid because  there are three cusps there is an anterior cusp  
tricuspid valve gets its name as tricuspid because  there are three cusps there is an anterior cusp  

a posterior cusp and a septal cusp that septal  cusp is largely immobile so it it doesn't move  
a posterior cusp and a septal cusp that septal  cusp is largely immobile so it it doesn't move  

during the opening and closing of the valve i'll  point this out to you we haven't quite covered it  
during the opening and closing of the valve i'll  point this out to you we haven't quite covered it  

in the videos yet but this is a branch of  the right coronary artery which is coming  
in the videos yet but this is a branch of  the right coronary artery which is coming  

around here called the av nodal branch because  it supplies the atrial atrioventricular node  
around here called the av nodal branch because  it supplies the atrial atrioventricular node  

with blood and we can see it  there kind of at the nexus of  
with blood and we can see it  there kind of at the nexus of  

the atrioventricular septum and  the interatrial septum as well
the atrioventricular septum and  the interatrial septum as well

so we've discussed the peculiarities of  
so we've discussed the peculiarities of  

features to the right atrium this is your  summary slide thank you for your time
features to the right atrium this is your  summary slide thank you for your time