nerves of the thorax and coronary vessels Flashcards
where does the right coronary artery originate from?
- originates from right aortic sinus
where does the left coronary artery originate from?
- originates from left aortic sinus
what is the positioning of the pulmonary artery and the aorta?
the pulmonary artery is anterior to the aorta
what are the main branches of the coronary arteries on the right?
- •Sino-atrial nodal artery
- •Right marginal artery
- •Posterior descending artery
what are the left main branches of the coronary artery?
- circumflex artery
- left anterior descending
learn the coronary arteries :
refer to netters card
label the grays anatomy coronary arteries
what does the sino atrial node supply?
what does the posterior interventricular branch of the right coronary artery supply?
- supplies the sino atrial node
- This mainly supplies the posterior and inferior part of the heart
overall what does the right coronary artery supply?
- supplies right atrium, right ventricle, SAN, AVN, •posteroinferior 1/3rd of interventricular septum and some of the posterior part of left ventricle
what does the Left anterior descending artery supply?
what does the Circumflex artery supply?
- . It supplies most of the anterior interventricular septum and the left ventricle
therefore very critical
- •. The circumflex mainly supplies the left atrium and the posterolateral part of the left ventricle
overall what does the left coronary artery supply?
- supplies most of the left atrium, left ventricle, atrioventricular branches, and bundles
what are the variations in arteries in the population?
2/3 population are right dominant coronary artery
1/3 of the population are left dominant coronary artery
what’s the difference between the left dominant coronary artery and right dominant coronary artery?
right dominant = the posterior descending comes off the right dominant therefore the right coronary supplies a large portion of the posterior wall of the left ventricle
Sino-atrial nodal branch also comes off right coronary artery.
whereas
left dominant = posterior descending comes off large left circumflex artery, supplying most of the posterior wall of left ventricle.
this time the sino-atrial nodal branch also comes off the left coronary artery
what happens in myocardial infarction?
- this is when the coronary artery gets blocked and the perfusion to the myocardium is insufficient to meet the demands of the muscle and therefore there is cell death and irreversible damage to the tissue
what does the severity of the disease depend on?
- size and location of the artery
- size of the blockage
- whether there are collateral blood vessels
what are the symptoms of the myocardial infarction?
- severe crushing pain
- sweating
- nausea
- pain radiating to the arms
label a spinal cord :
what does the grey matter contain
what does the white matter contain
grey matter contains the cell bodies
white bodies contains the axons in spinal tracts
where do sensory neurones come from?
where do motor neurones come from?
sensory neurons come from the dorsal horn - posterior roots
the motor neurons come from the ventral horn - anterior roots
what kind of nerve is the phrenic nerve
where does it arise from ?
the phrenic nerve is a somatic nerve
- it arises from the cervical nerves C3, C4, C5
to combine to make 2 phrenic nerves
what is the course of the phrenic nerve?
Left: over the aortic arch
Right: lateral to Superior Vena Cava
what is the function of the phrenic nerve?
- sensory nerve to the diaphragm, mediastinal pleura, pericardium
- motor neuron to the diaphragm
(‘C3,4,5 keeps the diaphragm alive’)
where might diaphragmic pain be referred to?shoulder tip (C3,4,5 dermatome).
shoulder tip (C3,4,5 dermatome).
the same spinal nerves supplying this dermatome
what are the intercostal nerves?
Somatic nerves arising from the anterior rami of spinal nerves T1-T11
they form a lateral cutaneous branch
- that ends as an anterior cutaneous branch
function of intercostal nerves?
- somatic motor function to the muscles of the thoracic wall
- •Somatic sensory sensation from overlying skin and parietal pleura
where does sympathetic and parasympathetic arise from?
sympathetic: thoracolumbar
nerves T1-L2
parasympathetic:
(CN 3,7,9,10 and S2-s4)
what does the White ramus communicans and Grey ramus communicans contain?
White ramus communicans contains myelinated preganglionic sympathetic fibres
Grey ramus communicans contains unmyelinated postganglionic sympathetic fibres
what is the parasympathetic cardiac innervation?
Efferents: ￬HR, ￬contraction, constrict coronary arteries
what is sympathetic innervation to the cardiac?
↑HR, ↑contraction
what is the cardiac plexus?
- The cardiac plexus is formed of small mixed nerves – containing both sympathetic and parasympathetic nerves
how do sympathetic nerves reach the cardiac plexus?
•reach the heart via cardiac branches from the right and left vagal nerves, they synapse at ganglia either at the plexus or in the walls of the atria
how do sympathetic nerves reach the cardiac plexus?
- through cardiac nerves from the sympathetic trunk
- Preganglionic = fibres from T1-T5 enter and move through the sympathetic trunk to synapse at cervical or upper thoracic ganglia
- •The postganglionic fibres then travel to the cardiac plexus from both sides of the spinal cord
what does parasympathetic and sympathetic do to the bronchioles?
Parasympathetic (vagus) nerves – constrict bronchioles
Sympathetic nerves – dilate the bronchioles
how does the cardiac conduction system work?
- impulses begin at the SAN
- excitation signal spreads across the atria causing atrial contraction
- The AVN is then stimulated, which is located near the opening of the coronary sinus
- The impulses then travel along the atrioventricular bundle
- This splits into the right and left bundle branches which then become continuous with the purkinje fibres
- , the electrical impulse serves the papilllary muscle and ventricular musculature
- ventricles contract and blood is forced out
what is most important for preventing backflow of blood into the right ventricle
A.Pulmonary sinuses
