1-Differential Diagnosis of Chest pain Flashcards
what is an example of visceral reflex afferent pathway?
visceral reflex afferent pathway = reflex sensory nerves from organs
example = baroreceptors are sensory receptors that detect changes in blood pressure. The afferent (sensory) fibers from baroreceptors (which are part of visceral reflex system) predominantly travel in vagus nerve
what is visceral afferent innervation and
a) how do pain fibers travel?
b) how do visceral reflex afferents travel?
= sensory nerves travelling from organs.mostly similar route - travel through autonomic nerves, enter spinal cord at dorsal roots
a) pain fibres from visceral organs can travel to spinal cord alongside both sympathetic & parasympathetic nerves (so pain fibres travel same pathway as sympathetic & parasympathetic nerves to spinal cord)
b) visceral reflex afferents = sensory nerves responsible for reflex activities in response to changing condition, mostly travel in vagus nerve but some also travel in accessory nerve (CN XI)
what sympathetic neurotransmitter is released at ganglion synapse of
a) presynaptic neuron and post synaptic neuron?
b) post synaptic fibre connecting ganglion & organ?
a) acetylcholine
b) noradrenaline
what parasympathetic neurotransmitter is released at ganglion synapse of
a) presynaptic neuron and post synaptic neuron?
b) post synaptic fibre connecting ganglion & organ?
a) acetylcholine
b) acetylcholine
where do presynaptic sympathetic fibres exit?
they travel inferiorly in spinal tract & exit from T1-L2 = thoracolumbar outflow
what are the 5 options of what sympathetic nerves do once exit spinal cord?
*for sympathetic innervation of heart - only 1st 3 relevant
- into ganglion and synapses at same level it exited
- can travel superiorly through sympathetic chain and synapse higher up
- travel inferiorly and synapse at lower ganglion
- pass straight through sympathetic chain ganglion without synapsing, as abdominopelvic splanchnic nerves to synapse in one of prevertebral ganglia of abdomen e.g. celiac ganglion
- pass straight to adrenal medulla without synapsing as an abdominal pelvic splanchnic nerve
what are splanchnic nerves?
= preganglionic neurons that don’t synapse at sympathetic ganglia but travel to organs etc
- preganglionic nerve fibers exit spinal cord and travel to sympathetic chain ganglia
- when reaching sympathetic chain ganglia, some synapse with post ganglionic neurons in ganglion
- however some nerves don’t synapse and become splanchnic nerves composed of preganglionic neurons and travel as bundles of nerves outside sympathetic chain
what are some types of splanchnic nerves?
- abdominopelvic splanchnic nerves
- cardiopulmonary splanchnic nerves
what is cardiac plexus and what is it made up of?
plexus = intertwining of nerves
made up of:
1. sympathetic fibres
2. parasympathetic fibres
3. visceral afferent fibres
what are cardiopulmonary splanchnic nerves?
they are post synaptic fibres from cervical & upper thoracic sympathetic chains
how do parasympathetic signals reach organs - where do they exit?
craniosacral outflow:
cranial nerves: (from head)
- CN III = oculomotor
- CN VII = facial
- CN IX = glossopharyngeal
cranial nerve CN X = vagus nerve (from chest & upper abdomen)
sacral level of spinal cord = to organs of the lower abdomen, pelvis & perineum
what splanchnic nerves are parasympathetic?
pelvic splanchnic nerves
what is route of presynaptic parasympathetic fibres?
- they travel in vagus nerve
- when they approach chest & upper abdomen organs they branch into smaller nerve fibres
- in ganglia (that are on target organs wall), they synapse and are then called post-synaptic neurons
- these post synaptic neurons within the ganglia have short axons that extend to nearby tissues and allow signals etc
what is outflow of
a) sympathetic?
b) parasympathetic?
a) thoracolumbar
b) craniosacral
what does somatic pain feel like?
body wall = sharp, stabbing, well localised
what does visceral pain feel like?
organ =dull, achy, nauseating, hard to place exactly where pain comes from
what are examples of places causing somatic pain?
- muscular
- joint
- bony
- intervertebral disc
- fibrous pericardium
- nerve
what are examples of places causing visceral pain?
- heart & great vessels
- trachea
- oesophagus
- abdominal viscerae
what is radiating pain?
pain felt in centre of chest and felt spreading from there e.g. to upper limbs, back, neck
what is referred pain?
pain ONLY felt at site remote from area of tissue damage in chest e.g. upper limbs, back, neck
what is route of action potential if you poke someone in dermatome T5?
prod →skin mechanoreceptors stimulated in T5 dermatome (specifically the anterior ramus part of dermatome)
- travel anterior ramus of T5
- pass into spinal nerve
- into dorsal root ganglion
- dorsal root
- dorsal rootlet
- synapsing within T5 spinal cord segment
- pain pathway cross spinal cord to opposite side (up until now been on right, now left)
- pass up left hand side of spinal cord
- come into consciousness on opposite side of cerebral cortex
why is central sulcus improtant?
important for differentiating motor & sensory info
what is function & location of postcentral gyrus?
- action potentials arrive here and bring body wall (somatic) sensations into consciousness (somatosensory)
- posterior of parietal lobe
what is function of precentral gyrus?
- action potentials originating here bring about contractions of body wall (somatic) skeletal muscle (somatomotor)
- anterior (frontal lobe)
what is the sensory homunculus?
illustrates areas of cerebral cortex where sensations from different body wall structures reach consciousness
(there’s an equivalent motor homunculus)
why if prod on right - the action potential is brought into consciousness on the left?
as it crosses over
what are examples of sharp somatic chest pain?
- herpes zoster (shingles)
- muscle, joint & bone
- parietal pleura & fibrous pericardium
what type of pain is linked with herpes zoster (shingles)?
- reactivation of dormant virus in posterior root ganglion
- pain can be felt anywhere in that dermatome
- pain precedes with blisters
- patient with shingles developing T4/T5 dermatome may present with central chest pain
what type of pain is linked with muscle, joint and bone?
- pectoralis major or intercostal muscle strain
- dislocated costochondral joint
- costovertebral joint inflammation
- slipped thoracic intervertebral disc
- all can be felt as central chest pain
what are causes of pain linked to parietal pleura & fibrous pericardium?
- pleurisy
- pericarditis
what are areas that cause dull central chest pain?
visceral
- oesophagus (oesophagitis)
- heart (angina & myocardial infarction)
- abdominal viscerae (gastritis; cholecystitis; pancreatitis; hepatitis)
- aorta (ruptured aneurysm of aortic arch)
- trachea (tracheitis)
what are the subdivisions of the mediastinum?
- superior
- inferior split into: anterior, middle, posterior
how do you know where to seperate superior & inferior mediastinum?
line drawn at sternal angle & T4 intervertebral disc
what are the azygous veins function?
role in draining venous blood from intercostal spaces. crosses over top of hilum of the lung and then joins with superior vena cava
where does right and left vagus nerve run?
both run posterior
right = travels along with trachea then passing posterior to root of the lung and then heads onto surface of oesophagus before passing to diaphragm
left = crossing left side of aortic arch heading posterior to the lung hilum towards the oesophagus
what is the ligamentum arteriosum?
a remnant of ductus arteriosus connecting pulmonary trunk to arch of aorta
what is the main duct draining lymph from all over the body?
thoracic duct - found in posterior mediastinum
what is the function of cardiopulmonary splanchnic nerves?
they have dual functions:
- conveying post synaptic sympathetic nerves towards the heart
- conveying visceral afferents away from the heart - towards CNS
where do visceral afferents action potentials travel in brain?
they pass bilaterally to thalamus & hypothalamus the diffuse areas of the cortex
why can brain get confused about where exactly pain is coming from?
→both somatic sensory fibers from body wall and visceral afferent from organs entering at same level
- so from heart - entering at thoracic and lower cervical levels and at chest levels also entering at same level
- this can lead to confusion in brain to exactly where pain is coming from →leads to radiating & referred pain
what is radiating pain?
The PAIN is felt BOTH at the actual site of the pathology AND ALSO radiating (spreading away from there)
- If the pain is originating in a somatic structure the radiation is along the affected dermatome(s)
- If from the heart the 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 referred pain?
In REFERRED PAIN, the sensation of pain is “felt” ONLY at a site remote from the actual area of injury or disease
why do we feel referred pain?
- Due to afferent (sensory) fibres from soma and afferent (sensory) fibres from viscera (visceral afferents) entering the spinal cord at the same levels
- The brain chooses to believe that the pain signals coming from the organ, are actually coming from the soma
- The famous anatomist & surgeon John Hunter called referred pain a “delusion of the mind”
- in CARDIAC referred pain the brain chooses to believe the pain signals are coming from the upper limbs (especially the left upper limb) or from the back, neck (or jaw).
what are the different types of heart attack?
- The “type” of MI is described clinically according to which SURFACE of the heart has been affected, e.g.:
- Anterior MI
- Inferior MI
- Anterolateral MI
*this is why i need to know what arteries supply what area of heart
where do coronary arteries arise?
from the right & left aortic sinuses of the ascending aorta
what are the most common sites of coronary atherosclerosis?
- anterior interventricular branch (LAD)
- RCA - right coronary artery
- circumflex of left coronary artery branch
- left (main stem) coronary artery
what is triple vessel disease?
narrowing of 3 vessels
= treated by triple bypass
what is CABG?
coronary artery bypass grafting
- grafts anastomosed proximally to ascending aorta
- grafts anastomosed to coronary artery distal to narrowing hence narrowing bypassed
- can use arteries like radial artery, great saphenous vein or internal thoracic artery by pedicle (means one end remains intact and cut end redirected to area of heart tissue that requires blood to be restored)
what makes up CNS?
brain & spinal cord = central controllers
what makes up PNS?
PNS has autonomic nervous system as subdivision (parasympathetic & sympathetic make up autonomic nervous system)
all tissues not in CNS:
- spinal nerves (connect spinal cord)
- cranial nerves (connect with brain)
- autonomic nerves (sympathetic & parasympathetic nerves = power organs, muscles, glands)
how is vagus nerve a conduit for parasympathetic nerves?
vagus nerve is a pathway for parasympathetic signals go from brain stem along vagus nerve and then into a parasympathetic nerve to reach the target organs or tissue
