Flashcards in *Anatomy 2 Deck (64):
What are the 3 links that can be made between the heart and nerves?
Dual motor control of the heart (sympathetic and parasympathetics)
Visceral afferent nerves
Conducting system of the heart and arrhythmia
How does the autonomic innervation reach the heart? - sympathetics, parasympathetics and visceral afferent nerves
Via the cardiac plexus
What is the effective the sympathetic nerves on the heart? (2)
Increases heart rate
What is the effect of the parasympathetic nerves on the heart?
Decreases heart rate
What types (2) of viscera afferent nerves are involved in the heart?
Visceral reflex afferents (e.g. from baroreceptors)
How do pain fibres travel to the spinal cord?
Alongside sympathetic nerves
Where do visceral reflex afferents mainly travel in?
The vagus nerve
For sympathetic innervation, what is the neurotransmitter than synapses between the axon of the presynaptic neurone and cell body of postsynaptic neurone?
For synaptic innervation, what is the neurone that connects between the ganglion and organ?
What do presynaptic sympathetic fibres from the brain do?
Travel inferiorly within spinal cord tracts and then exit the spinal cord in one of T1-L2/3 spinal nerves (thoracolumbar) and then can do 1 of 5 options
What are the 5 things that sympathetic signals which have traveled within the spinal cord and exited in one of T1-L2/3 can do?
What are the 3 options that are involved with the sympathetic stimulation of the heart?
Go into the ganglion (in sympathetic chain) of that level and synapse
Travel superiorly in the sympathetic chain to another ganglion and synapse
Travel inferiorly in the sympathetic chain to another ganglion and synpase
Pass through the sympathetic chain ganglion without synopsis, as abdominopelvic splanchnic nerves, to synapse in one of the pre-vertebral ganglia of the abdomen
Pass straight to the adrenal medulla without synapsing as an abdominopelvic splanchnic nerve
Top 3 are options for stimulation of heart
What are the names of the cervical sympathetic ganglia?
Inferior cervical sympathetic ganglia
What are the names of the postsynaptic fibres which provide sympathetics to the heart and lungs?
Cardiopulmonary splanchnic nerves
What ganglia have nerves that come out of them to produce the cardiopulmonary splanchnic nerves?
T1-T5 ganglia and cervical ganglia
For essentially midline organs such as the heart is there unilateral or bilateral sympathetic innervation?
What is the cardiac plexus made up of?
Visceral afferent fibres
What is the neurotransmitter released by both the presynaptic and postsynaptic fibres of parasympathetic fibres?
How do the parasympathetic reach the organs?
Through cranial nerves III, VII, IX, and X and the sacral spinal nerves
How many parasympathetic ganglia are in the head?
4 (1 for occulomotor nerve , 2 for facial nerve and 1 for glossopharyngeal nerve)
How does the presynaptic parasympathetic fibres from the vagus nerve reach the organs?
Synapse onto postsynaptic neurones (with short axons in ganglia within the walls of the organs of the chest and upper abdomen)
What provides parasympathetic innervation to the organs of the lower abdomen, pelvis and perineum?
The pelvic splanchnic nerves
What does the vagus nerve innervate?
All the organs from the neck, chest and abdomen as far as the end of the midgut
Where does the vagus nerve attach to the heart?
At the SA node
What travels in the cardiopulmonary splanchnic nerves?
Postsynaptic cardiac sympathetic efferent
Cardiac visceral afferent
Where are the visceral afferent nerve endings in the heart located for stretch and chemicals? (8)
Inner aortic arch
Around the SA node
Outflow tracts from both ventricles
Root of aorta
What are chemoreceptors?
any of the special cells or organs adapted for excitation by chemical substances and located outside the central nervous system.
What are 2 examples of chemoreceptors?
Aortic bodies (in root of aorta)
What is pain? (definition)
An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage
In anatomical/ physiological terms, what is pain?
Stimulation of sensory receptor
Afferent action potential reaches brain
We "feel" the pain according to the part of the brain that is stimulated by the action potential
What are the potential sources of central chest pain? (2)
Typical nature of somatic central chest pain?
Sharp, stabbing, well localised
Is the fibrous pericardium and parietal pleura somatic or visceral?
What is the typical nature of visceral central chest pain?
Dull, aching, nauseating, poorly localised
What is radiating central chest pain?
Pain felt in the centra of the chest and felt spreading from there to other places e.g. upper limbs, back, neck
What is referred pain?
Pain is felt only at a site remote from the actual area of injury or disease
What happens when someone is hurt in the T5 dermatome?
Skin mechanoreceptors in the T5 dermatome are stimulated
Pain pathway crosses in spinal cord
AP travels to the brain until sensation reaches consciousness at cerebral cortex
Where do somatic afferent signals arrive bringing somatic sensations into consciousness?
Primary somatosensory area - postcentral gyrus of parietal lobe
Where do APs originate bringing about contractions of somatic skeletal muscle?
Precentral gyrus of frontal lobe (primary somatomotor area)
What is the name of the fissure between the frontal and parietal lobes?
What are potential causes for "sharp" somatic chest pain?
Herpes zoster (shingles) - patients with shingles developing in T4/T5 dermatome may present with central chest pain
Muscle, joint and back e.g. pectoralis major or intercostal muscle strain
Parietal pleura and fibrous pericardium e.g. pleurisy and pericarditis
What are some causes of "dull" (visceral) central chest pain sources? (5)
Heart (angina and myocardial infarction)
Aorta (ruptured aneurysm or aortic arc)
Abdominal viscerae (e.g. gastritis, etc.)
What is the name of the remnant of the ductus arterioles connecting PT to arch of aorta?
How do visceral afferents pass to the brain from the organs?
They travel alongside the sympathetic (splanchnic) nerves except at the spinal cord they enter via posterior roots with somatic sensory nerves
Where visceral afferent APs pass in the brain?
Bilaterally to thalamus and hypothalamus then diffuse areas of the cortex
If the pain is originating in a somatic structure, where will the pain radiate?
Along the affected dermatome
Where can pain from the heart radiate?
Radiation is to the dermatomes supplied by the spinal cord levels at which the cardiac visceral afferents enter the sympathetic chain/ spinal cord i.e. bilaterally to cervical and upper thoracic dermatomes
What is the principle behind referred pain?
(very similar principle to radiating pain) - due to afferent (sensory) fibres from soma and afferent fibres from viscera entering the spinal cord at the same levels, the brain can choose to believe that the pain signals coming from the organ, are actually coming from the soma
Where can cardiac referred pain be felt?
Upper limbs (especially left side)
What is a myocardial infarction?
Irreversible death (necrosis) of part of the myocardium due to occlusion of its arterial blood supply
What is another name for the lateral branch of the LAD?
Does the right coronary artery or left coronary artery supply most of the heart in most people?
Right - right dominant pattern (some people also have an unusual extreme right dominant pattern)
What kind of coronary artery dominancy do 15% of patients have?
Left dominant pattern
Which coronary artery is most likely to be narrowed/ occluded?
LAD of LCA (40-50%)
Which coronary artery is the second most likely to be narrowed/ occluded?
Which coronary artery is the 3rd most likely to be occluded/ narrowed?
Circumflex branch of LCA (15-20%)
Which coronary artery is the 4th most likely to be occluded/ narrowed?
Left (main stem) coronary artery
During CABG, where are the grafts anastomosed?
Proximally to the ascending aorta and distally to distal of the narrowing
What are 3 commonly used grafts for CABG?
Great saphenous vein (superficial vein of the lower limb)
Internal thoracic (internal mammary) artery
What develop if the conducting tissue of the heart is damaged by ischaemia?
An arrhythmia can develop
What provides blood supply to the SA node in about 60% of patients?
SA nodal branch of the RCA
What provides blood supply to the AV node in about 80% of patients?
AV nodal branch from RCA
What 2 arteries provide blood supply to the left and right bundle branches?
Posterior interventricular artery
What type of arrhythmia can develop if the AV node is damaged?
Complete heart block