Heart and great vessels Flashcards
What shape is the heart visualised as, and what are the surfaces?
Cone. Apex anteriorly to the left, base is posterior. Diaphragmatic surface is inferior, 2x pleural surfaces laterally, and a superior surface.
Where does the apex normally meet the chest wall?
left 5th intercostal space, mid-axillary line.
Describe the pericardium
2 serous layers and 1 surrounding fibrous layer. The fibrous layer is tough and attaches to surrounding structures to stabilise it (inc. great vessels, sternum and diaphragm). between the 2 layers of serous pericardium (visceral & parietal) lies pericardial fluid.
Where is the crista terminalis?
RA. From SVC –> IVC.
Where is the opening of the coronary sinus?
RA
Where does the right coronary artery come from and what does it feed in to?
From anterior aortic sinus. Give off marginal and posterior interventricular branches.
Where does the left coronary artery come from, and what does it give?
from left posterior aortic sinus. Give LAD and circumflex arteries.
What forms the venous system of the heart?
1) veins accompanying coronary arteries drain into coronary sinus.
2) Small anterior cardiac veins drain wall of RV and open into RA.
3) venae cordis minimae drain from wall of heart directly into chambers of heart.
What are the functions of the fibrous skeleton?
1) electrophysiological disontinuity everywhere except conducting regions.
2) mechanical attachment
3) maintain cardiac position
4) attachment for valves.
Describe the path of electrical impulse from the SAN to ventricles.
SAN –> atria –> AVN –> bundle of His (2x) –> purkinje fibres –> Ventricles.
Where does the cardiac plexus lie?
Deep - around bifurcation of trachea.
Superficial - around arch of the aorta.
Where do sensory nerves from the heart pass?
Via the cardiac plexus to dorsal root of spinal cord of T1-T4. The sensory nerves are stimulated by ischaemia. This feels like pain.
What is the region for referred pain from the heart?
Somatic areas supplied by T1-T4. (i.e. inner arm and upper chest.)
Other than ischaemia, what can sensory nerves from the heart and great vessels detect?
baroreceptors and chemoreceptors can detect BP and CO2 (+O2) levels. These fibres pass in the vagus nerve and form part of the reflex pathway to control BP.
Describe the distribution of sensory fibres in the pericardium.
Visceral pericardium supplied by autonomic fibres - no pain. (?)
Fibrous and parietal pericardium have sensory neurones, which travel via the phrenic (a somatic) nerve. Referred pain often over c3-c5.
