ENGLISH NOTES Flashcards
WHAT IS THE LOCATION OF THE HEART AND ITS ANATOMICAL RELATIONSHIPS?
• Snugly enclosed within the middle mediastinum (medial cavity of thorax).
Contains: - Heart o Pericardium o Great Vessels o Trachea o Esophagus.
- M.Mediastinum – located in the inferior mediastinum (lower than the sterna angle)
- Extends obliquely from 2nd rib à 5th intercostals space. • Anterior to Vertebrae
- Posterior to Sternum • Flanked by 2 lungs
- Rests on the diaphragm
- 2/3 of its mass lies to the LHS of the midsternal line.
The Pericardium: (Coverings of the Heart)
- A double-walled sac
- contains a film of lubricating serous fluid
- 2 Layers of Pericardium:
-
Fibrous Pericardium:
- Fibrous Pericardium:
- Serous Pericardium:
Fibrous Pericardium:
- Tough, dense connective tissue
- Protects the heart § Anchors it to surrounding structures
- Prevents overfilling of the heart – if fluid builds up in the pericardial cavity, it can inhibit effective pumping. (Cardiac Tamponade)
Serous Pericardium: (one continuous sheet with ‘2 layers’)
- Parietal Layer – Lines the internal surface of the fibrous pericardium
- Visceral Layer – (aka Epicardium) Lines the external heart surface
Layers of the Heart Wall:
- Epicardium:
- Myocardium
- •Endocardium:
Epicardium
Epicardium: Visceral layer of serous pericardium
Myocardium:
Muscle of the heart o The layer that ‘contracts’
Endocardium
• Endocardium:
- Lines the chambers of the heart (Endothelial Cells)
- Prevents clotting of blood within the heart
- Forms a barrier between the O2 hungry myocardium and the blood. (blood is supplied via the coronary system)
Fibrous Skeleton of the Heart:
- • La red de fibras de tejido conectivo (colágeno y elastina) dentro del miocardio
- • Ancla las fibras musculares cardíacas + válvulas + grandes vasos.
- • Refuerza el miocardio
- • Proporciona aislamiento eléctrico
- • 2 partes: Septums and Rings
Septums
Septums:
- Flat sheets separating atriums, ventricles & left and right sides of the heart.
- Electrically isolates the left & right sides of the heart (conn. Tissue = non-conductive)
- • Important for cardiac cycle
- (interatrial septum/atrioventricular septum/interventricular septum)
Fibrous rings
- -Rings around great vessel entrances & valves
- stop stretching under pressure
Cardiac Chambers & Associated Great Vessels:
- 2 Atrias (superior): [Atrium = Entryway]
- 2 Ventricles (inferior): [Vent = Underside]
Atrias (superior): [Atrium = Entryway]
Thin-walled Receiving Chambers:
On the superior aspect of heart (above the ventricles).
Each have a small, protruding appendage called Auricles – increase atrial volume.
Separated by Atrial Septum (Site of Foetal Shunt Foramen ovale) Right ans left Atrium:
Right Atrium:
Ridged internal anterior wall – due to muscle bundles called Pectinate Muscles.
-Blood enters via 3 veins:
- Superior Vena Cava
- Inferior Vena Cava
- Coronary Sinus (collects blood draining from the myocardium)
