38 - Heart and Pericardium Flashcards
What is the pericardial sac adherent to?
Central tendon of diaphragm
What limits descent of diaphragm in inspiration?
Pericardial sac is attached to central tendon
Name for central structure in thorax
Mediastinum
Mediasteinum
Central part of thoracic cavity, surrounded by connective tissue.
Divisions of mediastinum
Superior and inferior. Hear divides inferior mediastinum into anterior and posterir
Where does the heart sit in relation to vertebrae?
In front of T5-T8
Divisions of pericardium
Fibrous is external sheath. Serous pericardium is divided into parietal (which lines internal aspect of fibrous pericardium) and visceral (lies against heart) pericardium.
Left-to-right parts of the heart, if anterior surface is viewed
Right atrium, right ventricle, left ventricle
What makes up the apex of the heart?
Left ventricle
Where is the apex of the heart located?
Intersection between mid-clavicular line and 5th T rib.
How to orient heart
Auricles (or atrial appendages) face forwards. These look like fingers grasping the great vessels of the heart
Landmarks in right atrium 1) 2) 3) 4) 5) 6)
1) SVC and IVC entrances 2) Fossa ovalis in inter-atrial wall 3) Coronary sinus 4) Musculi pectinati cover outer wall. 5) Musculi pectinati terminate at crista terminalis 6) Tricuspid valve
Function of coronary sinus
Where venous blood from coronary veins drains to
Parts of right ventricle covered by trabeculae carnae
All of right atrium, except for small patch near pulmonary artery, which is smooth (infundibulum or conus arteriosus)
Arrangement of trabeculae carnae in right ventricle
All attach to walls of ventricle, except for three atypical trabeculae carnae. These attach to ventricular wall and project to centre of ventricle, where they join chordae tendinae.
Name for three atypical trabeculae carnae in right ventricle
Papillary muscles
Fibrous skeleton of heart
Layout of tricuspid valves
Number of papillary muscles joining to tricuspid valve
Three
Number of papillary muscles joining to bicuspid valve
Two
Part of left ventricle which has musculi pectinati
Left atrial appendage. Has different embryological origin to the rest of left ventricle
How to chordae tendinae attach to cusps of bicuspid and tricuspid valves?
One chordae tendon attaches to two cusps. Ensures that all cusps close together.
Name for fibrous structure surrounding semilunar valves
Coronets in fibrous skeleton
Name for fibrous structure surrounding tricuspid and bicuspid valves
Rings
Where do muscles of the ventricles attach?
To the rings of the fibrous skeleton
Muscles joining to rings of fibrous skeleton
Muscles of the ventricles and muscles of the atria attach to the rings. These muscles are separate, and are electrically-isolated.
Difference between atrial and ventricular surfaces of bicuspid and tricuspid valves.
Ventricular surface is rough, has attachment of chordae tendinae. Atrial surface is smooth
Are there any extra structures (EG: chordae tindinae) associated with semilunar valves?
No
Where do the coronary arteries begin?
Just after the aortic valve. Sit just above aortic sinuses
Conduction system of the heart
Innervation of the heart 1) 2) 3)
1) Cardiac plexus situated at base of the heart. 2) Divided into a superficial and deep part 3) Receives branches from vagus and sympathetic trunks
Location of AV node
In right atrium, between coronary sinus and tricuspid valve
Blood supplies of AV and SA nodes
~60% of time branch from early right coronary artery supplies SA node
~80% of time right coronary artery supplies AV node
Where does the left coronary artery begin?
Starts between left atrial appendage and the great vessels of the heart
Can anastamoses between coronary ateries compensate if one is occluded?
No. The coronary arteries are functionally end arteries.
The anastomoses are at the arteriolar level. Can’t supply enough blood to compensate.
