Atria Flashcards
Where does the pulmonary circulation drain into?
The left atrium through the pulmonary veins
Where does the systemic circulation drain into?
The right atrium through the superior and inferior vena cava
What is ventricular filling mostly?
Passive
When does the atria contract?
Not until the end of diastole
What happens to the atria during contraction?
Becomes essential to match the speed of ventricular filling to the increased rate of ventricular contraction
Describe the atrioventricular orifice
The aperture in which blood flows from the right atrium to the right ventricle. The tricuspid valve is positioned here
Describe the atrioventricular node (AV)
The electrical relay station between the atria and ventricles. It is located in the posteroinferior region of the interatrial septum near the opening of the coronary sinus
Describe the crista terminalis (terminal crest)
It is the origin of the pectinate muscles. The sulcus terminalis (on the external surface) acts as a surface marking for the internal crista terminalis
Describe the fossa ovalis
An embryological remnant of the foremen ovale.
What is the foramen ovale?
Is a hole between the two atria in a foetal heart
Describe the interatrial septum
The firbomuscular wall between the left and right atrium. The fossa ovalis and the AV node is located here
Describe the opening of the coronary sinus
The coronary sinus is the main cardiac vein. It is where the deoxygenated blood drained from the heart itself returns to the hearts circulation
Describe the pectinate muscles (comb like muscles)
These are parallel ridges in the walls of the atrium
Describe the right auricle
Also known as the right atrial appendage - it is a muscular pouch that acts to increase the capacity of the atrium
Describe the sinoatrial node (SA)
The pacemaker of the heart. It is located in the posterior wall of the right atrium, inferolateral to the opening of the vena cava, along the superior part of the crista terminalis
Describe the sulcus terminalis
A shallow depression marking the point of fusion between the venous part of the right atrium and the true right atrium. The crista terminalis sits on the internal surface of this structure
What are the features in the left atrium?
Atrioventricular orifice, fossa ovalis, interatrial septum, left auricle and pectinate muscles
What is the left auricle also known as?
The left atrial appendage
Describe the atrioventricular (left)
The aperture in which blood floes from the left atrium to the left ventricle. The bicuspid (mitral) valve is positioned here
What features are found in the right atrium?
Atrioventricular orifice, atrioventricular node, crista terminalis, fossa ovalis, interatrial septum, opening of the coronary sinus, pectinate muscles, right auricle, SA node and sulcus terminalis
