innervation of the heart wall Flashcards
autonomic innervation of the heart
fibres travelling in the vagus nerves
how does parasympathetic system control heart rate
(controlling heart rate) and in spinal cord segments T1-4
how does the sympathetic system control heart rate
(controlling heart contraction) are routed to the heart and coronary arteries via the cardiopulmonary nerve plexus situated at the bifurcation of the trachea.
sensory and pain fibres of the heart
fibres from the heart wall travel to spinal cord levels T1-4 in the sympathetic nerves.
(Changes in blood pressure, etc., travel back in the vagus nerves to the brain).
somatic sensory fibres of the heart and relation to the upper arm
in the above spinal nerves T1-4 supply the dermatomes on the inner aspect of the upper arm.
So, pain coming from the heart from these segments is interpreted by the brain as coming from these dermatomes instead of the heart, particularly those from the left upper arm, and so pain from the heart (e.g., angina pectoris) is said to be referred to these upper arm dermatomes because these are stronger impulses than the autonomic ones)].
what innervates the SA node and AV node
sympathetic motor fibres
Why is angina pain referred much more often to the left upper arm than the right?
The usual answer given for this is that the heart is situated more to the left side of the chest and so the brain will interpret the pain impulses as coming from the left arm more frequently than it does the right arm, although right arm pain has also been known to occur.
location of SA node
lies near the opening of the SVC in the right right upper chamber (atria)
location of AV node
lies in the inferior part of the the Koch triangle,[1] near the coronary sinus on the interatrial septum
location of atrioventricular bundles of his
lie within each side of the ventricular
Septum
