5. Heart and nerves of the thorax Flashcards
Pericardium
Fibro-serous sac surrounding heart and its great vessels Consists of 2 layers: Fibrous and Serous Serous has 2 parts: Parietal: lines fibrous Visceral: adheres to heart
How many pericardial sinuses are there? Describe each
2
Transverse pericardial sinus: separates arteries from veins
Oblique pericardial sinus: is formed by reflection onto the pulmonary veins of heart
Where would you palpate to feel the apex beat of the heart?
5th intercostal space
Describe the outflow of chambers of the heart
Right atrium: Blood returns via SVC and IVC (body) and coronary sinus (heart)
Left atrium: Blood returns via pulmonary veins
Right ventricle: Outflow to the pulmonary trunk
Left ventricle: Outflow to the ascending aorta
Coronary sinus
Point at which main drainage veins of heart (Coronary veins) empty into right atrium
What does the foramen oval provide?
1st opportunity for blood to bypass lungs in foetal circulation
Blood can flow from the right atrium to the left atrium
What happens to the foramen oval after birth?
Closes after birth
Becomes the fossa ovale
What happens to the ductus arteriosus after birth?
Becomes the Ligamentum arteriosum connects PT to aortic arch
Chordae tendonae in the right ventricle
Chordae tendonae stop inversion of tricuspid valve.
How are chordae tendonae arranged in the ventricles
Embedded in the wall of the ventricle by projections (papillary muscles)
Pair of semilunar valves
Pulmonary valve
Aortic valve
Pair of atrioventricular valves
Mitral
Tricuspid
Left ventricle structure
Much thicker left ventricle wall
Trabecular carnae: net like structure
Papillary muscles tether chordae tendonae, preventing eversion of mitral valve
What are the “bowl” like structures forming the aortic valve are called?
Aortic sinuses
Describe the aortic sinuses
In the walls of 2 aortic sinuses there is a hole for the coronary arteries (2 have holes as we have 2 coronary arteries). These with holes are called coronary aortic sinsues.
The 1 aortic sinus with no hole is called a non-coronary aortic sinus
Myocardial Infarction
Lack of blood to the heart muscle causes it to die
Ischaemic event
Blood supply issue
Cardiac arrest
Arrest of beat of heart
Electrical issue
Interventricular branches
Branches that go down between ventricles
Marginal branches
Branches that run across margins
Circumflex branches
Branches that turn back on themselves
Right dominant coronary artery
More common variation
Posterior interventricular branch arises from the right coronary artery
Left dominant coronary artery
Less common variation
Posterior interventricular branch arises from the left coronary artery
Where do coronary veins drain?
All Coronary veins drain into coronary sinus
(vessel that sits between left atrium and left ventricle).
Collects deoxygenated blood from heart muscle and returns it to the right atrium
Describe the conducting system of the heart
Excitation begins in SAN
Spreads wave of depolarization across atria causing contraction
Concurrently wave stimulates AVN
Travels through the bundle of His
Then along bundle branches, through Purkinje fibres, causing ventricular contraction
What does the somatic nervous system innervate? (voluntary)
Skin
Skeletal muscles