Internal Features of the Heart Flashcards
Structure of the right atrium
Main cavity and a small out pouching called the auricle
What structure separates the right atrium from the right auricle?
Outside: Sulcus terminalis
Inside: Crista terminalis which forms a ridge
The sulcus terminalis overlies the location of the sinoatrial (SA) node in the musculature of the crista terminalis near the orifice of the SVC
Characteristics of the posterior wall of the right atrium
Smooth walled
Derived from sinus venosus
Characteristics of the anterior wall of the right atrium
Roughened/trabeculated surface
Derived from the primitive atrium
Which structures open into the right atrium?
Superior vena cava
Inferior vena cava
Coronary sinus
Other small veins draining the wall of the heart
What is the infundibulum?
Funnel-shaped part of the right ventricle near the pulmonary orifice
What is the trabeculae carnea?
Smallest naturally arising collection of linearly arranged myocytes in the heart
Form projecting ridges which give a sponge like appearance to the ventricular wall
What are the three types of trabeculae carnea?
Papillary muscles
Chordae tendinae
Moderator band
What valve lies in the right atrio-ventricular orifice?
Tricuspid valve
How are the cusps of the valve formed?
Fold of endocardium with connective tissue enclosed
What are the names of the cusps forming the tricuspid valve?
Anterior, septal and inferior (posterior) cusps
How are the cusps attached to the heart?
Bases of the cusps are attached to the fibrous ring of the skeleton of the heart
Free edges and ventricular surfaces are attached to the chordae tendineae
Function of the chordae tendinae
Connect the cusps of the valve to the papillary muscles
Function of atrio-ventricular and pulmonary orifice
Atrio-ventricular orifice: Enables communication between right ventricle and right atrium
Pulmonary orifice: Enables communication between the right ventricle and the pulmonary trunk
What is the moderator band?
Muscular band which crosses the ventricular cavity from the septal to the anterior wall
It forms the right branch of the atrioventricular bundle
Structure of the left atrium
Main cavity + left auricle
What structures open into the left atrium?
Four pulmonary veins
Left atrioventricular orifice
Structure of the left ventricle?
Walls of the left ventricle are thicker than the right ventricle
Trabeculae carneae is well developed: Two large papillary muscles and no moderator band
Part of the ventricle below the aortic orifice is called the aortic vestibule
What valve lies in the left atrio-ventricular orifice?
Mitral valve/bicuspid valve
Origin of the sympathetic and parasympathetic cardiac fibres
Cardiac plexus of the autonomic nervous system
Parasympathetic fibers reach the cardiac plexuses in the vagus nerves
Sympathetic stimulation of the heart
Cardiac acceleration, increased force of contraction by the cardiac muscle and dilatation of the coronary arteries
Parasympathetic stimulation of the heart
Reduces heart rate & force of contraction
Constricts coronary arteries
Surface markings of the heart
Right Border
Convex line on the right side of the thorax
Extends from the 3rd to 6th right costal cartilage
Inferior Border
Extends from the 6th right costal cartilage to the left 5th intercostal space
Apex
In the left 5th intercostal space in the midclavicular line, 9cm from the median plane
Left Border
Convex line on the left side of the thorax
Extends from the Apex to the 2nd left costal cartilage
Superior Border
Line joining 2nd left costal cartilage to 3rd right costal cartilage
Surface markings of the heart valves
Pulmonary valve: Lies behind the medial end of 3rd left costal cartilage and the adjoining part of sternum
Aortic valve: Lies behind the left half of the sternum opposite 3rd intercostal space
Mitral valve (left AV valve): Lies behind the left half of the sternum opposite the 4th costal cartilage
Tricuspid valve (right AV valve): Lies behind the right half of the sternum opposite 4th intercostal space
