The Art of Physical Pain
The Common Vein Copyright 2021
“Awakened with the Worst Pain in My Life”
This is the pain that rattles emergency room physicians as they know the diagnosis to exclude is the potentially fatal condition of a ruptured berry aneurysm in the cerebral circulation. The pain is unbearable for the patient and is a somatic pain caused by blood irritating the meninges.
89081pd04b07.8s pain headache sleep woken awakened from sleep worst pain in my life headache 10 out of 10 ruptured berry aneurysm bleed blood hemorrhage meninges somatic
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key words pain abdomen sleep woken awakened from sleep somatic peritoneal peritonitis
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key words tree in bud nociceptors free nerve endings trees in the body Davidoff art copyright 2008 87559pb04b07b.8s
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The mechanical pressure sensitive nociceptors are dominantly located in the organs and are responsible for sensing pressure changes. The diagram shows a wave of increased pressure (pale yellow) impinging on the free nerve endings of the pressure receptors, with red nerve endings being stimulated by the pressure.
87559pb04b02b11.8s pressure receptors nociceptors mechanoreceptors free nerve endings trees in the body
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The diagram illustrates the many chemical factors, each represented in different color and different shapes, that can incite the chemical nociceptors. The hydrogen ion and acidic PH is a common stimulant of these receptors.
87559pb04b02b02b02.8s nociceptors chemical receptors free nerve endings trees in the body hydrogen ion algogenic substances autocids substance C K+ kinins interleukins adenosine histamine leukotrines H+
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74771c06.8 head and neck pain headache above the eyes above the ears CTscan volume rendering 3D
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Seconds Minutes and Hours
77118c.81 time clock duration seconds minutes hours
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77119b01 time duration age Monday Tuesday Wednesday Thursday Friday Saturday Sunday
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77119b04 time months seasons age one year colors white = cold light pink = early spring pink = early summer green = early summer blue = summer pale yellow = mid summer bright yellow = late summer orange = early fall brown = late fall dark gray = early winter light gray = winter white = mid winter very light pink = late winter
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Severity of Pain
77114c.88 Davidoff pain scale modification Wong Baker no pain minimal mild moderate moderately severe severe ignored interferes with tasks interferes with concentration interferes with basic needs needs bed rest white green blue maroon orange red
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This CT shows a reconstruction of the face with attention to the air filled structures. Of particular interest to headache are the paranasal sinuses . The maxillary sinuses are overlaid in orange while the ethmoid sinuses and the more posterior sphenoid sinuses cannot be separated in this anteroposterior view (green). Lastly the frontal sinuses are seen overlaid in dark orange just above the orbits. Other sources of pain demonstrated in this image include the eyes and obits, the ears, mouth teeth and pharynx, and ears
head and neck face nose ears eustachian tubes concha nasopharynx oropharynx mastoid air cells air filled structure maxillary sinus air filled structure maxillary sinus paranasal sinuses light orange = maxillary sinuses green = combination of ethmoid sinuses and sphenoid sinuses dark orange = frontal sinuses normal anatomy CTscan 3D volume rendering
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In the above diagram and through the text, we attempt to depict the nature of the pain diagramatically. The more severe pains are shown in brighter red and the spiculated shapes reflect sharper pain. Thus the top left image is severe burning retrosternal pain characteristic of GERD with esophagitis. The top middle image is a pressure type pain that radiates o the neck, characteristic of angina and sometimes seen in esophageal spasm. The top right image is a more diffuse discomfort or pressure and is seen in angina and myocardial infarction. The bottom left image is sharp lancinating severe almost devastating pain characteristic of acute aortic dissection. The focal sharp pain in the middle image aggravated by deep inspiration is characteristic of pleuritc pain and pericarditis, whil the pain along a dermatome on bottom right is seen in herpes zoster (shingles).
71197c05a 71197c07a 42540c02a05 71197c08a 71197b03p 71197c04a
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a) No pain – excercise b) Pain Pressure Typical Distribution c) Relieved by Rest, TNG
Angina is characteristically a dull pressure like pain, that is precipitated by stress usually after a predictable distance of a walk or run for example. In a, the patient has no discomfort, develops pain after a fixed distance, and then stops. The pain is relieved
71197c07c substernal chest pain burning esophagus heart cardiac esophagitis reflux substernal chest pain radiating to neck and left arm relieved by rest and sublingual nitroglycerine angina CTscan 3D
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(a )is prior to the event, (b) Sudden Severe Pain Pressure Discomfort (c) Unrelieved by TNG and Rest and 1 hour later
In the diagram above, image a represents the patient without pain before the event. Sudden and evolving chest discomfort or pressure with radiation to the neck and left arm occurs (b) that is not relieved with nitroglycerine, and remains for longer than 20 minutes (c) suggests an acute coronary syndrome.
71197c08c.800 substernal chest pain burning esophagus heart cardiac esophagitis reflux retrosternal chest pain radiating to neck and left arm unrelieved by rest and sublingual nitroglycerine myocardial infarction time hours CTscan 3D
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This diagram shows denudation of the endothelial layer with exposure and rupture of the contents of the atherosclerotic plaque in volcanic fashion into the lumen. This event is catastrophic and can result in acute thrombosis and may even be a fatal event. 33801d Courtesy Ashley Davidoff MD. code heart artery atherosclerosis atheroma vulnerable plaque drawing Davidoff art
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The most characteristic feature of the pain of pericarditis is that it is relieved by sitting up or forward. Image a shows the characteristic sharp pain occurring in the precordium, as being intense and pleuritic in nature aggravated by coughing and deep breathing but relieved by sitting up, and shallow breathing (b). The pain is also aggravated by lying down, (c) but is relieved by sitting forward (d)
76031c01d02 chest heart pericardium pain aggravated by coughing and deep breathing relieved by shallow breathing and sitting forward acute pericarditis pericardial effusion lateral chest X-ray plain X-ray
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This image is intended to reflect the severe (bright red) lancinating, sharp, thunderbolt like character (spiculated shape) of the chest pain that the patient with acute dissection may experience. One moment the patient is healthy without symptoms (a) and the next, there is catastrophic pain that reaches maximum intensity at the time of onset. (b) This is one of the pain syndromes in medicine one fears. It represents the one of the most severe forms of chest pain one can experience.
71197c10c chest pain character shearing sharp lancinating acute aortic syndrome aortic dissection penetrating ulcer acute aortic hematoma ruptured aorta ruptured dissection CTscan
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The pain of dissection may be felt either in the front of the chest and or the back. Either way the pain can have similar characteristics – ie sharp, thunderbolt like, severe, and rapidly and almost instantaneously reaching maximum intensity coincident with the onset.
but can 49640c06 chest pain character shearing sharp lancinating acute aortic syndrome aortic dissection penetrating ulcer acute aortic hematoma ruptured aorta ruptured dissection CTscan
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The lumen of the aorta with blood is demonstrated in red. The intima of the wall is the thin light pink layer just under the red luminal layer. The media or elastic layer is in teal, while the outer layer is a light yellow color (a)
This diagram illustrates the progression from a ulcerated plaque (a), to a mural hematoma(b). The ulcer in c has penetrated the into the media itself and is called a penetrating ulcer with a mural hematoma. (c). In d, a small focal dissection with flowing blood is seen, and this can either thrombose or progress to a full dissection(e) or penetrate through the wall and be contained (e) or eventually rupture into the mediastinum (f)
42409c01.800 aorta artery atherosclerosis atheroma acute aortic syndrome a aortic ulcer b = acute mural hematoma c = acute mural hematoma large d = focal dissection e penetrating ulcer f rupture histology histopathology Davidoff art pathogenesis
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The pleuritic pain demonstrated on the right side of this patient is characterized by focal intense (bright red) and sharp pain that is aggravated by deep breaths and by coughing. The location corresponds to the disease and to the images described below.
71197b03p chest lung pleura pleuritic pain PE pulmonary Embolus pneumonia pleurisy aggravated by deep inspiration coughing rib fracture pleuritic pain pleurisy CTscan 3D
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This diagram re-enforces the concept of the pleuritic pain being related to respiratory movements and is focal and overlying the disease process. The outer part of the diagram represents the expanded lung of inspiration and the inner less voluminous lung represents the deflated lung of expiration. The green wedge represents the infarcted are of lung from the pulmonary embolus that abuts and involves the visceral and parietal pleura.
42540c02d lung inspiration expiration pain on inspiration focal severe pain pleuritic pain PE pulmonary embolus
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The pleuritic pain of pulmonary embolus, pneumonia or pleurisy is not distinct in itself, but the associated findings relating to the specific disease will help differentiate the variety of causes of pleuritic chest pain. Peripheral based pneumonia abuts the pleural surface and parapneumonic pleural inflammation involves both the visceral pleura and the parietal pleura. When the lung moves with respiration the rubbing of inflammed structures and particularly the pleura brings about the sharp focal pleuritic pain localized over the pneumonia.
In this instance a
42540c02a01 lung inspiration expiration pain on inspiration focal severe pain pleuritic pain PE pulmonary embolus
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  Tall ThinYoung – Spontaneous Pneumothorax with Mediastinal Shift |
| This is the type of CXR that sends shivers down the spine. The overall blackness of the left chest cavity, in association with a nubbin of lung tissue in the ipsilateral hilum and rightward mediastinal shift is characteristic of a tension pneumothorax with total atelectasis of the left lung. Immediate and urgent decompression with a chest drain is indicated. One must also remeber that if a tall thin young patient presents with chest pain the diagnosis of dissecting aneurysm in a patient with Marfans syndrome has to be considered.
Courtesy Ashley Davidoff MD 42525 code lung pleura dx tension pneumothorax plain film CXR 5star medical students |
 The pleuritic pain is sharp, severe, and aggravated by deep breathing and coughing and relieved by shallow breathing and lying ipsilateral side down. The image on the right shows an overall increase in density of the right chest suggestive of a pleural effusion which is non specific and may accompany many of the diseases discussed. 42540c08 44665
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   Dull Pain, Burning Sensation, and Angina-like symptoms
GERD |
| GERD with or without esophagitis and spasm can often masquerade as cardiac pain varying from substernal discomfort, and pressure like symptoms, to substernal pain and burning (b) to discomfort that radiates to the neck and shoulder (c) but also is sometimes relieved by nitroglycerine. The pain however is not precipitated by excercise nor relieved by rest.
71197c06a 71197c05a substernal chest pain burning esophagus heart cardiac esophagitis reflux angina MI myocardial infarction subsernal chest pain CTscan 3D Courtesy Ashley Davidofff MD |
 Pain Relieved by nitroglycerine- Unrelated to Excercise and Rest |
| The diagram illustrates a patient without pain (a) who develops substernal pain radiating to the neck and left shoulder. He takes nitroglycerine and the pain is relieved. (c) The pain was however not related to excercise and was not relieved by rest and lasted 10 minutes. Wht is the most likely cause of the pain? Sometimes esophageal spasm associated with GERD can respond to nitroglycerine and this is th most likely diagnosis. The patient however should undergo a stress test to ensure that he does not have ischemic heart disease.
71197c07c substernal chest pain burning esophagus heart cardiac esophagitis reflux substernal chest pain radiating to neck and left arm relieved by rest and sublingual nitroglycerine angina CTscan 3D Courtesy Ashley Davidofff MD |
 Band Like Interscapular Pain |
| The interscapular band like back pain is part of both lower chest and upper abdominal disease.
49640c03 chest back pain belt interscapular band like pancreas gallbladder retroperitoneum retroperitoneal structures CTscan Courtesy Ashley Davidoff MD 3D |
 Dermatomal Pain |
| Pain that distributes along a dermatome is characteristic of Herpes Zoster (aka shingles) The dermatomes involved are usually thoracic and between one and 3 dermatomes are involved with burning and sometimes severe pain associated with a rash with vesicles.
71197c04 skin chest pain dermatome pain herpes anatomy CTscan 3D volume rendering Courtesy Ashley Davidoff MD |
 Anatomic Distribution of Back Pain |
| 48390.83 bone back pain spine lumbar spine thorax thoracic cage pancreatitis aortic syndrome CTscan Courtesy Ashley Davidoff MD |
 Rheumatoid Arthritis – Painful to Look at! |
| The classical fetures with severe arthritis, involving the proximal interphalangeal joints and the carpal joints with resulting ulnar deviation and severe osteopenia are charcateristic features of rheumatoid arthritis. Neck pain in a patient with this entity requires an alertness of associated involvement of the cervical spine and the most serious involvement is related to the C1-C2 joint.
75627.800 bones hands carpal metacarpal interphalangeal joints erosions ulnar deviation joint space loss osteopenia arthritis RA rheumatoid arthritis inflammation shape position wrists plain X-ray plain film Courtesy Ashley Davidoff MD |
  Quadrants of the Abdomen |
| 49703b19 71203.800 chest abdomen pelvis sternum bone ribs iliac crest femur femoral neck pubic symphisis ischium ischial tuberosity scapula clavicle lung heart pericardium liver stomach small bowel colon femoral artery normal anatomy CTscan 3D surface rendering Courtesy Ashley Davidoff MD |
 Abdominal Aortic Aneurysm |
| 74089c01 aorta abdominal aorta enlarged aneurysmal surface rendering calcifications 5.2cms AAA 3D CTscan Courtesy Ashley Davidoff MD |
 Key Elements Relating to Many Causes of Back Pain |
| The oblique projection of the plain film of the spine exposes the neural foramen with its pair of nerves (yellow) and intervertebral disc(a) and shows the intimate relationship between the disc, the nerves and the facet joints. The second image (b) shows the disc impinging on the nerve, while image c shows osteophytes from the vertebral bodies impinging on the nerves and foinally image d shows the effect of osteophytes of the facet joints impinging.
71741b07c01 a) = normal b) = disc protrusion c) = ostephytes off the vertebral bodies d) = osteophytes off the facet joints bone spine facet joints pedicles oblique spine intervertebral disc spaces vertebral body vertebral body osteophytes DJD degenerative disc joint disease nerve impingement pedicles neural forammen nerves plain X-ray Courtesy Ashley Davidoff MD |
 75018c02 |
| 75018c02 bone lumbar spine disc disease with disc herniation intervertebral disc space narrowing vacuum phenomenon sclerosis CTscan Courtesy Ashley Davidoff MD |
 Forward Slippage – Anterolisthesis of L5 on S1 |
| 73860c04 bone lumbar spine sacrum lumbosacral junction L5 – S1 5th lumbar vertebra position spondylolysis spondylolisthesis geade 2 plain x-ray Courtesy Ashley Davidoff MD |
 Compression Fractures – mild, moderate, and severe |
| 76123c03 spine bone 86 year old female with severe compression fracture of T12 (green) moderate compression of T11 (orange) and mild compression of L3 (teal) back pain lumbar spine thoracic spine impacted rectum CTscan Courtesy Ashley Davidoff MD |
 Ruptured Pseudoaneurysm of the Right Common Iliac Artery |
| 75727c03 elderly man with acute pelvic and back pain aorta iliac artery RLQ right lower quadrant artery pseudoaneurysm ruptured aneurysm retroperitoneal hematoma hemorrhage CTscan Courtesy Ashley Davidoff MD Courtesy Rebecca Schwartz MD 75727c01 75727c02 75724c01 75727c03 |
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| Nociceptors and their Pathway to the Spinal Cord
The sensory receptors of the nociceptors are found in the tissues peripherally (top left) and are connected by a long fiber that transmits the impulse to the ganglion cell that lies in the dorsal ganglion in the neural canal alongside the spinal cord. 83066b09.8sb nociceptor A delta fober C fiber pain stimulus neuron receptor afferent pathway sensory dorsal ganglion dorsal column sensory pathway Davidoff Art Copyright 2008 |
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A Delta Fiber The A delta fiber consist of free nerve endings, are of intermediate size, are minimally myelinated (yellow sheath) and consist of a long peripheral process and a short central process, which connects the neuron to the dorsal horn in the gray matter of the spinal cord. 883066c02bd.8s This diagram shows A delta fiber whic is minimally myelinated, consists of the receptors in the top left hand corner that when stimulated transmit the impulse via a long afferent neuron to the cell body lying alongside the spinal column. This fiber is relatively thin, and conducts the impulse at about 15-30m/s. nerve sensory system nociceptor A delta fober C fiber pain stimulus neuron receptor afferent pathway sensory dorsal ganglion dorsal column sensory pathway Davidoff Art Copyright 2008 |
C Fiber |
| The C fiber are small in size, are non myelinated, and consist of a long peripheral process and a short central process, which connects the neuron to the dorsal horn in the gray matter of the spinal cord.
83066c02c.8s This diagram shows the two types of receptors and fibers that transmit the pain impulse. The upper fiber is called the C fiber and it is non myelinated, consists of the receptors in the top left hand corner that when stimulated transmit the impulse via a long afferent neuron to the cell body lying alongside the spinal column. This fiber is relatively thin, and conducts the impulse at about 2m/s. nerve sensory system nociceptor A delta fober C fiber pain stimulus neuron receptor afferent pathway sensory dorsal ganglion dorsal column sensory pathway Davidoff Art Copyright 2008 |
 Types of Receptors Subtending the A delta Fibers and C Fibers |
| The diagram shows sensory stimuli including sharp pressure, extreme heat and cold as well as chemical, stimulating the free nerve endings of the nociceptors that are linked to the myelinated A delta fiber , and non myelinated C fiber. The myelinated fiber will conduct the impulse between 3 and 15 times faster than the non myelinated fiber.
87559pc08b03.8s pain free nerve ending nociceptor A delta fibres C fibres heat cold pressure mechanical prick afferent somatosensory nerves somatic anatomy normal Davidoff art Copyright 2008 |
 The Dorsal Root Ganglion of the Afferent Neurons |
| The dorsal root ganglion is a focal accumulation of the first order nerve cells of the sensory component of the peripheral nerve. (orange) It is situated in the neural foramen of the vertebral body. The central process emanates from the ganglion cell and ends in the dorsal horn.
83067b03b04.8s peripheral nerve sensory nerve motor nerve dorsal root ganglion dorsal horn pain pathway spinal cord Davidoff Art Copyright 2008 |
 From the Spinal Cord to the Brain and Perception of the Pain
The Three Orders of Neurons |
| The stimulus is converted into an electrical impulse which is taken by a first order sensory nerve (orange) to the spinal cord (dorsal root ) which in turn transports the impulse via second order neuron (dark blue and light blue) to the thalamus,. The third order neuron (pink) transports the impulse to the somatosensory cortex.
77533b06d06.8s pain skin joint muscle nociceptors dorsal root ganglion spinal cord brain thalamus sensory cortex somatosensory cortex postcentral gyrus pain perception localization perceive Davidoff art Copyright 2008 |
 Fibers involved in Gate Control Mechanism |
| This diagram shows the three types of receptors and fibers that transmit impulses related directly and indirectly to pain . The upper fiber is called the C fiber and it is non myelinated, consists of the receptors in the top left hand corner that when stimulated transmit the impulse via a long afferent neuron to the cell body lying alongside the spinal column. This fiber is relatively thin, measuring between .4 to 1.2 micrometers, and conducts the impulse at about 2m/s. The second neuron is the A delta fiber and it responds to the pricking or sharp sensation that is first felt and reacted to. It is weakly myelinated and is about 2-6 micro meters thick, and conducts the stimulus with a velocity of between 15-30 meters per second. The last fiber is the A beta fiber and it is responsible for the pressure component which indirectly affects response to pain by affecting the gate mechanism of pain. It is greater than 10 microns thick due to heavier myelination and conducts impulses at 30-100meters per second
fiber neuron long peripheral process short central process ganglion cell ganglion body nerve sensory nerve dorsal ganglion dorsal column synapse Davidoff art Courtesy Ashley Davidoff MD Copyright 2008 83066c05b.8s |
 Second Order Neurons
Cross Over and entry into the Spinothalamic Tract |
| The pain fibres cross over the spinal cord via the second order neuron (blue) to the spinothalamic tract. The lateral spinothalamic tract and the anterior spinothalamic tract There are two parts to the anterolateral spinothalamic tract. The lateral spinothalamic tract (darker blue) carries the fibers for pain and temperature sensations and the anterior spinothalamic tract (light blue) carries sensation of simple touch.
orange = sensory nerve carrying stimuli from periphery blue = anterolateral spinothalamic tract dark blue = lateral spinothalamic tract light blue = anterior spinothalamic tract Davidoff art Courtesy Ashley Davidoff MD copyright 2008 83067b05b05.8s |
 C Fibers and the Reticular Acivating System |
| The image represents a coronal cut of the brain attained using T2 weighted MRI technique. It reveals a second order neuron (blue) traversing the medulla, pons, and midbrain, and in its path the C fiber component, is able to activate the RAS (pink). The stimuli reach the thalamus (orange) which not only activates the sensory cortex but other parts of the cortex as well as shown by the red lines.
C fibers pain brain reticular activating system RAS thalamus cortex medulla oblongata midbrain thalamus MRI T2 weighted Courtesy Ashley DAvidoff MD copyright 2008 77059c02.8s |
 The Somatosensory Cortex – Post Central Gyrus |
| The somatosensory cortex is overlaid in light rose pink in the diagram above and represents the most anterior structure of the parietal lobe. It lies posterior to the motor cortex (blue) which is part of the frontal lobe, behind the central sulcus and in front of the post central sulcus. It serves to perceive, localize and evaluate intensity of the pain, as well as initiate the response to the pain.
83029b01.b1.81s brain somatosensory cortex pareital lobe medial longitudinal fissure medially central sulcus anteriorly postcentral sulcus posteriorly lateral sulcus inferiorly location of primary somatosensory cortex main sensory receptive area touch. maps sensory space homunculus in this location pink = somatosensory cortex in post central gyrus blue = motor cortex The Common vein Davidoff art copyright 2008 |
 Somatosensory Cortex in the Parietal Lobe
Localization and the Homunculus Man |
| The diagram reflects the relative functional sensory space each body part occupies in the somatosensory cortex. Those structures with high density of sensory receptors are represented by a larger size, while those with a lesser concentration of sensory apparatus shown as being “smaller” in size. Hence the mouth lips, hands feet and genitalia have a relatively large representation. The homunculus man (literally the “little man”) is the distorted figure drawn to reflect the concept of size of organ paralleling the size of the sensory innervation.
somatosensory cortex (sensory homunculus) spinothalamic tract spinal cord thalamus sensory cortex homunculus man penis clitoris genitals genitalia foot body thigh abdomen chest and face mouth eyes lips viscera somatosensory Davidoff art Copyright 2008 38610b09.46k.8s |
The Sodium Potassium Pump – Resting Membrane Potential |
| Cell membranes in general and the neurons more specifically have resting membrane potentials of betweeen -70mV to -90mV The inside wall is relatively negative compared to the outside charge on the other side of the membrane which is relatively positive. This is due to the sodium and potassium pump. Sodium (orange) is the major player and under basal resting conditions it is forcefully and actively evicted from the cell by a pump (big orange arrow). To a lesser extent, potassium is pushed into the cell (big purple arrow). The chemical gradients that result cause passive but lesser movements of sodium into the cell (small orange arrow) and potassium out of the cell (small purple arrow).72045b04.800 nerve conduction force electricity electric force positive force negative force sodium pump Na pump Patassium pump K+ pump diffusion conduction of impulses Davidoff drawing Davidoff art Davidoff MD |
Potentials Across the Membrane |
| The diagram illustrates some of the terms described in reference to the yellow nerve where resting potential (green) is -70mV, threshold (teal) is -55mV, and the peak voltage reached (red) is +30mV. 72045 d01b03b02.8s nerve resting membrane potential negative positive threshold potential peak electrical gradient normal physiology Davidoff art Copyrght 2008 |
The Stimulus Causing Sodium Gate to Open |
| The first event after the stimulus (red asterisk and red arrow) is mainly one of opening an ionic gate that will allow sodium to rush into the cell.72045 d01b04e01.8s nerve resting potential threshold stimulus sodium gate opened Davidoff art copyright 2008 |
Sodium Gate Opened |
| When the nerve fiber is stimulated, the sodium gate is opened. If the stimulus is not intense enough, the threshold is not reached, an action potential is not generated and the stimulus is not sensed. In this diagram, the red arrow and red star reflect the stimulus, the sodium gates on the top of the diagram ope and sodium ions rush in, and the upward trend of the orange line on the graph is caused by the influx of sodium through the open gates. Since the threshold level of -55mV has not been reached, no action potential is generated, and the stimulus therefore is not sensed or recognized.72045 d01b04h01.81s stimulus sodium gate open sodium rushes in depolarisation not to threshold stimulus is strong enough to keep gates open and sodium continues to rush in nerve resting potential threshold stimulus sodium gate opened Davidoff art copyright 2008 |
Cause of Depolarisation |
| In this instance, the threshold level of -55Mv following the stimulus (red arrow and red star) has been reached and an immediate action potential is generated that causes depolarization to +30mv. This action occurs in about .5milliseconds and is the result of the entry of sodium ions into the cell while the sodium gate is open. The inside of the cell at that point of the action potential is now positive and the outside is negative.72045 d01b04j.8s stimulus sodium gate open sodium rushes in depolarisation to threshold sodium continues to rush in action potential all or nothing physiology normal peak electrical potential of 30mV nerve resting potential threshold stimulus sodium gate opened Davidoff art copyright 2008 |
Beginning of Repolarization |
| After the discharge or depolarization and resulting action potential, (orange line) the sodium gates close and the potassium gates open allowing potassium (purple arrow) to rush out of the cell.72045 d01b04l.8s stimulus potassium gate open potassium rushes out and start of repolarisation action potential all or nothing peak electrical potential of 30mV potassium gates open potassium rushes out physiology normal peak electrical potential of 30mV nerve resting potential threshold stimulus sodium gate opened Davidoff art copyright 2008 |
Repolarization and a Little More |
| The diagram shows a return of the potential to below base levels (purple line) caused by a more than enough exit of potassium ions through the potassium “exit gate”72045 d01b04n.8s stimulus potassium gate open potassium rushes out and start of repolarisation action potential all or nothing peak electrical potential of 30mV potassium gates open potassium rushes out physiology normal peak electrical potential of 30mV nerve resting potential threshold stimulus sodium gate closed more potassium than necessary exits causing an overshoot of baseline Davidoff art copyright 2008 |
Action Potential Complete Propogation Initiated |
| Early on at the peak of positivity of the orange line before the potassium gate opened, a region of the fiber was relatively positive on the inside and relatively negative on the outside (black positive signs on inside of cell). In addition the rest of the fiber during this time was opposite in charge with the inside of the cell negative and the outside positive. (basal conditions) So what now? There are positives and negatives that have to be electrically neutralized.72045 d01b13a02.8s nerve action potential complete propogation initiated physiology normal sodium gate closed potassium gate closed action potential Davidoff art Copyrght 2008 |
Start of Propagation Setting up of A local Circuit |
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The sodium that moved into the fiber caused a positive charge inside the cell and a negative on the outside which is in distinct contrast to basal conditions. Subsequently, circuits caused by movement of the charge from positive to negative are set up enabling the electrical impulse to proceed down the fiber. The diagram illustrates a fiber with a completed action potential at its peak. The black positive inside the fiber is shown with a yellow negative outside in one area of the nerve fiber. This area is juxtaposed to opposite charges of the resting conditions and circuit of movement of the charges positive to negative is set up. 72045 d01b13a04.8s propogation of electrical charge nerve sensory nerve action potential propogation both ways down the nerve fibre depolarise repolarise normal physiology nerve conduction Davidoff art copyright 2008 |
Local Repolarization |
| A cascade of electrical movements occurs along the gradient set up along the nerve, as charges move and create new circuits. 72045 d01b13a06b.8s propogation of electrical charge transmission nerve sensory nerve action potential propogation both ways down the nerve fibre depolarise repolarise normal physiology nerve conduction Davidoff art copyright 2008 |
Transmission and Return to the Baseline |
| As the impulse is propagated, the resting potential returns with a negative charge on the inside and a positive charge on the outside.72045 d01b13a05e.8s progressive resestablishment of negative charge on the inside and positive charge on the outside propogation of electrical charge nerve sensory nerve action potential propogation both ways down the nerve fibre depolarise repolarise propagation normal physiology nerve conduction Davidoff art copyright 2008 |
The Propagation Continues Returning To Resting Conditions |
| 72045d01b13a054b.8s progressive resestablishment of negative charge on the inside and positive charge on the outside propogation of electrical charge nerve sensory nerve action potential propogation both ways down the nerve fibre depolarise repolarise propagation normal physiology nerve conduction Davidoff art copyright 2008 |
The Synapse in the Dorsal Horn |
| The diagram shows the synapse (red ring) that enables the connection between the incoming neuron with a “processing unit” in the dorsal horn of the spinal cord that coordinates the input of multiple other stimuli and influences. The long process of the first order neuron brings the stimulus from the periphery to the nerve cell in the dorsal root ganglion. The short process takes the stimulus from there and transmits it to the synapse.83066b08e.8s nociceptor A delta fober C fiber pain stimulus neuron receptor afferent pathway sensory dorsal ganglion dorsal column sensory pathway synapse presynaptic ending post synaptic ending synaptic cleft Davidoff Art Copyright 2008 |
Synapse |
| The synapse consists of a presynaptic ending, a synaptic cleft or space between the two connecting neurons, and a post synaptic ending. 72046b04a.8s mitochondria transmitter vesicles presynaptic terminal post synaptic terminal soma of neuron synaptic cleft acetyl choline norepinephrine dopamine serotonin forces chemical energy function principles Davidoff art Davidoff drawing Davidoff MD |
Smaller Components of the Synapse |
| Within the presynaptic ending there are vesicles that contain the neurotransmitters and a voltage sensitive gate that releases calcium ions when stimulated called the voltage gated calcium channel. It also contains mitochondria and other organelles that are responsible for the production and packaging of the neurotransmitters. Within the post synaptic ending, there are gated ion channels with chemical receptors that enable the generation of electrical signals.72046b04d.8s presynaptic ending synaptic ceft post synaptic ending voltage gated calcium channel chemical gated ion channel neuroceptors synaptic vesicles containing neurotransmitters membrane voltage mitochondria nerve sensory berve synapse dorsal horn first order neuron second order neuron normal mitochondria voltage gated calcium channel synaptic cleft chemical gated ion channel organelles synaptic vesicle neurotransmitters physiology Davidoff art copyright 2008 |
Resting Membrane Potentials in Both Neurons |
| The resting membrane potential is created in both the first order neuron and the nerve it is linked to in the synapse. In both instances the resting potential is created by the Na+ K+ ATPase pump measures about -70mV.72046b04b03.8s presynaptic ending synaptic ceft post synaptic ending voltage gated calcium channel chemical gated ion channel neuroceptors synaptic vesicles containing neurotransmitters membrane voltage mitochondria nerve sensory berve synapse dorsal horn first order neuron second order neuron normal physiology Davidoff art copyright 2008 |
The Signal Arrives at the Synapse |
| In this diagram, the orange arrow indicates the direction of the electrical impulse and depolarization that has reached the synapse and caused a relatively positive charge on the inside and negative charge on the outside. When this charge is felt by the voltage gated calcium channel on the presynaptic nerve, a reaction takes place.
72046b04b04.1.8s presynaptic ending synaptic cleft post synaptic ending voltage gated calcium channel chemical gated ion channel neuroreceptors synaptic vesicles containing neurotransmitters membrane voltage mitochondria nerve sensory nerve synapse dorsal horn first order neuron second order neuron impulse propagation transmission normal physiology Davidoff art copyright 2008 |
Voltage Gated Calcium Channel Calcium Released |
| The electrical impulse at the presynaptic terminal stimulates the release of the calcium ions.72046b04b04.2.8s presynaptic ending synaptic ceft post synaptic ending voltage gated calcium channel chemical gated ion channel neuroceptors synaptic vesicles containing neurotransmitters membrane voltage mitochondria nerve sensory berve synapse dorsal horn first order neuron second order neuron impulse propogation transmission voltage gated calcium channel releases calcium ions normal physiology Davidoff art copyright 2008 |
The Influence of the Ca++ ions on the Synaptic Vesicles |
| The electrical charge created by the calcium ions stimulate the release of the neurotransmitters into the synaptic cleft from the synaptic vesicles.72046b04b07.8s presynaptic ending synaptic ceft post synaptic ending voltage gated calcium channel chemical gated ion channel neuroceptors synaptic vesicles containing neurotransmitters membrane voltage mitochondria nerve sensory berve synapse dorsal horn first order neuron second order neuron impulse propogation transmission voltage gated calcium channel releases calcium ions stimulates synaptic vesicles normal physiology Davidoff art copyright 2008 |
Release of the Neurotransmitters in the the Synaptic Cleft |
| Release of neurotransmitters such as glutamate and substance P into the synaptic cleft causes the chemical gated ion channel on the receiving neuron to open and allow entry of sodium into the post synaptic ending. This again changes the electrical balance and allows the impulse to be transmitted.72046b04b09.8s presynaptic ending synaptic cleft post synaptic ending voltage gated calcium channel chemical gated ion channel neuroceptors synaptic vesicles containing neurotransmitters membrane voltage mitochondria nerve sensory nerve synapse dorsal horn first order neuron second order neuron impulse propagation transmission voltage gated calcium channel releases calcium ions stimulates synaptic vesicles to release neurotransmitters into the cleft which attach and stimulate specific receptors called chemical gated ion channel which results in sodium entry into the cell normal physiology. Davidoff art copyright 2008 |
A New Action Potential |
| The end result of the complex changes in the synapse is a net influx of positive charge dominated by sodium ions causing depolarization of the post synaptic neuron. If the charge is sufficient enough to supercede the threshold level, an action potential is initiated and an impulse is generated.generate a 72046b04b12.8s presynaptic ending synaptic ceft post synaptic ending voltage gated calcium channel chemical gated ion channel neuroceptors synaptic vesicles containing neurotransmitters membrane voltage mitochondria nerve sensory nerve synapse dorsal horn first order neuron second order neuron impulse propagation transmission voltage gated calcium channel releases calcium ions stimulates synaptic vesicles to release neurotransmitters into the cleft which attach and stimulate specifc receptors called chemical gated ion channel which results sodium entry into the cell and initiation of action potential normal physiology Davidoff art copyright 2008 |
Modulation Inputs on the Synapse |
| The orange fiber is one of many carrying the original pain stimulus as the first order neuron. It joins many nerves that synapse with the second order neuron in the dorsal horn, including the white A beta non nociceptor fiber, ascending (yellow) and descending (purple) tracts from other levels of the spinal cord, and descending tracts from the cortex, thalamus and other hgiher levels (green). 77533b01e05.8s modulation C fiber A delta fiber A beta neuron cortical input RAS autonomic nervous system frontal cortex sensory cortex thalamus descending pathway spinal input gate control theory synapse first order neuron Davidoff art copyright 2008 |
Opening and Closing the Gate – at the Substantia Gelatinosa |
| The diagram illustrates the gate control theory. The incoming pain fibers are carried by the A delta fibers and the C fibers seen on the bottom left of the diagram. They enter the substantia gelatinosa (SG) and through the connection with tract cell (T) they will cause the gate to be open and cause the pain to be transmitted. The A beta fibers on the other hand carry pressure signals and through the SG will cause the gate to be closed and prevent the pain fiber from being transmitted.gate contrrol theory pain A beta fibers A delta neurons c fibers substantia gelatinosa T cells dorsal horn of the spinal cord open gate gate closed Davidoff art Courtesy Ashley Davidoff MD copyright 2008 83168b06.8s |
Second Order Neurone with Modified and Modulated Impulse |
| The pain fibers cross over the spinal cord via the second order neuron (blue) to the spinothalamic tract. There are two components to the anterolateral spinothalamic tract. The lateral spinothalamic tract (darker blue) carries the fibers for pain and temperature sensations and the anterior spinothalamic tract (light blue) carries sensation of simple touch.The fibers are spatially arranged so that those coming from the cervical region (c), from the thorax (t) , lumbar (l) and sacral (s) regions are positioned in specific locations. Additionally within these tracts, the A delta and C fiber information is kept discrete allowing for qualitative cognition, while quantitative (ie intensity) information is also retained .
orange = sensory nerve carrying stimuli from periphery yellow white pink and green fibers – modifying neurones affecting the synapse through the process of modulation blue fiber – second order neuron blue tract = anterolateral spinothalamic tract dark blue tract = lateral spinothalamic tract light blue tract = anterior spinothalamic tract 83067b05b07.8s There are two parts to the spinothalamic tract. The lateral spinothalamic tract and the anterior spinothalamic tract There are two parts to the anterolateral spinothalamic tract. The lateral spinothalamic tract and the anterior spinothalamic tract. The lateral spinothalamic tract carries slow and fast fibers for pain and temperature sensations and the anterior spinothalamic tract carries sensation of simple touch. orange = sensory nerve carrying stimuli from peripheryblue = anterolateral spinothalamic tract dark blue = lateral spinothalamic tract light blue = anterior spinothalamic tract Davidoff art Courtesy Ashley Davidoff MD copyright 2008 |
The C fibers of the Spinothalamic Tract Activate the RAS |
| The reticular activating system (aka ascending reticular activating system, RAS) (red herring bone) is a part of the brain considered to be the center of arousal and motivation. Structurally it lies betweent the medulla oblongata and midbrain and is connected to the thalamus. (orange) In the instance of pain, the RAS is activated by the C fibers and hence pain can arouse us from sleep through the RAS, can create a sense of urgency, and can cause changes in heart rate or respiration rate. ascending spinothalamic tract
C -fibers neurons pain sharp pain RAS reticular activating substance arousal wakefulness thalamus MRI T2 weighted Courtesy Ashley Davidoff MD copyright 2008 77059c01b01.8s |
Nuclii in the Thalamus |
| Thalamic pain centres dominantly involve the ventroposteriorlateral (VPL) and venteroposteromedial (VPM) nuclei centeromedian and pulvinar nucleipain thalamus pulvinar MRI T2 weighted Courtesy Ashley Davidoff MD 38694c03b01.8s |
The Primary Somatosensory Cortex |
| The primary somatosensory cortex (salmon pink) lies in the front of the parietal lobe just posterior to the motor cortex. The next diagram advances the anatomy.83029b01.8s brain somatosensory cortex pareital lobe medial longitudinal fissure medially central sulcus anteriorly postcentral sulcus posteriorly lateral sulcus inferiorly location of primary somatosensory cortex main sensory receptive area touch. maps sensory space homunculus in this location The Common vein Davidoff art |
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The Somatosensory Cortex – Post Central Gyrus |
| The somatosensory cortex is overlaid in light rose pink lies posterior to the motor cortex (blue) which is part of the frontal lobe, behind the central sulcus and in front of the post central sulcus. It serves to perceive, localize and evaluate intensity of the pain, as well as initiate the response to the pain. 83029b01.b1.81s brain somatosensory cortex pareital lobe medial longitudinal fissure medially central sulcus anteriorly postcentral sulcus posteriorly lateral sulcus inferiorly location of primary somatosensory cortex main sensory receptive area touch. maps sensory space homunculus in this location pink = somatosensory cortex in post central gyrus blue = motor cortex The Common vein Davidoff art copyright 2008 |
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Somatosensory Cortex in the Parietal Lobe Localization and the Homunculus Man |
| When we view the primary somatosensory cortex in a coronal plane on this MRI we get reintroduced to the homunculus man whose body parts are draped over the somatosensory cortex. The homunculus man (literally the “little man”) is the distorted figure drawn to reflect the concept of size of organ paralleling the size of the sensory innervation. Those structures with a high density of sensory receptors are represented by a larger size, while those with a lesser concentration of sensory apparatus are shown as being “smaller” in size. Hence the mouth lips, hands feet and genitalia have a relatively large representation. The diagram also reflects the relative functional sensory space each body part occupies in the somatosensory cortex. somatosensory cortex (sensory homunculus) spinothalamic tract spinal cord thalamus sensory cortex homunculus man penis clitoris genitals genitalia foot body thigh abdomen chest and face mouth eyes lips viscera somatosensory Davidoff art Copyright 2008 38610b09.46k.8s |
Lateral Somatosensory Cortex (SII) Operculum and Insula |
| The lateral somatosensory cortex is centered around the Sylvian fissure (red) It incorporates the insula (purple) the upper lid of the operculum which is part of the parietal cortex (pink) as well as parts of the frontal cortex, and the lower lid of the operculum (green) which is part of the temporal lobe.38610c06b07.8s brain pain thalamus sensory affective somatosensory cortex S1 SII S2 parietal lobe Sylvian fissure lateral sulcus operculum insula affect emotional response limbic structures MRI T1 weighted Courtesy Ashley Davidoff MD copyright 2008 |
The Insula and the Operculum from the Inside (Coronal) and Outside (Sagittal View) |
| This diagram is utilized to demonstrate the operculum as seen from the inside in the first image (a) and from the outside in the second (b) Its cortical components consist of frontoparietal regions (pink) and temporal portions (green). The insula cortex is not visible from the outside (b) since it lies deep and medial (purple a). The Sylvian fissure is overlaid in red.71060c07.8c01.8s brain pain pathway somotosensory cortex S 2 SII insula operculum parietal lobe temporal lobe frontal lobe lateral sulcus Sylvian fissure MRI T1 weighted Courtesy Ashley Davidoff MD copyright 2008 |
Major Parts of the Limbic System |
| The diagram is an overlay of a sagittal view of the brain using a T2 weighted image that traverses the centre of the brain. The limbic system is a bilateral relatively centrally placed system. The top and largest belt (light green) is the cingulate gyrus. (cing) The second, smaller and inner belt (olive green )represents the fornix (for) superiorly and the hippocampus (hip) inferiorly that terminates in the amygdala (amyg, yellow) The amygdala is in close association with the thalamus (orange) and hypothalamus (hyp – teal blue). The mamillary body (royal blue can be seen at the anterior and inferior end of the fornix.71430.85c01s brain pain limbic system belt cingulate gyrus cingulate cortex hypothalamus mamillary body fornix hippocampus amygdala thalamus MRI T2 weighted Courtesy Ashley Davidoff MD copyright 2008 |
Basal Ganglia |
| 38610c06c05.8s brain pain basal ganglia striatum caudate nucleus putamen globus pallidus subthalamic nucleus. The striatumreceives cortical input globus pallidus exports to thalamus divided internal and external segment The substantia nigra is a midbrain structure that is reciprocally connected with the basal ganglia of the forebrain. globus pallidus subthalamic nucleus. striatum receives cortical input to the basal ganglia and can be divided into the cand the putamen. MRI T1 weighted coronal projection Courtesy Ashley Davidoff MD copyright 2008 |
Basal Ganglia |
| Signals coming up the spinothalamic tract into the thalamus (blue arrow) and then into the cortex White arrow to pink somatosensory cortex) are transmitted to the basal ganglia (teal arrow) including the caudate nucleus (c) and putamen. They distribute the signal to the other basal ganglia including the globus pallidus (gp), substantia nigra (sni), and subthalamic nuclii (sni) . The globus pallidus acts as the exit point for the basal ganglia (orange arrow) for the return of the processed signal to go to the thalamus.38610d10.8s A simplified drawing of the connections between the caudate nucleus (orange, the sensory cortex (salmon pink) and the basal ganglia is shown. After the stimulus has reached the sensory cortex for quantification and qualification it connects to the basal ganglia through the caudate nucleus and putamen. Each of these connect with the two parts of the globus pallidus (gp) which feed back to the thalamus. The caudate nucleus also feed back and forth to the substantia nigra (sni) and the subtalamic nucleus (snu) brain basal ganglia connections functional thalamus sensory cortex putamen= p caudate nucleus = cn globus pallidus = gp substantia nigra = sni subthalamic nucleus = snu Davidoff art MRI T1 Copyright 2008 |
Hypothalamus |
| The hypothalamus is centered in the midline around the third ventricle. The coronal image of a T2 weighted MRI shows the third ventricle in the midline (white) immediately surrounded by a the thinnest layer of paraventricular component, which in turn is surrounded by a slighly thicker layer of periventricular component (orange followed laterally by a pair of medial nuclii and then a single larger lateral component. The image below is a magnified version to enable you to appreciate the two inner layers better.60528.8c11.8s hypothalamus brain pain autonomic nervous system parasympathetic nervous system sympathetic nervous system third ventricle 3rd ventricle periventricular nuclii optic tract pituitary paraventricular nuclii lateral nuclii medial nuclii optic tract MRI T2 weighted image Courtesy Ashley Davidoff MD copyright 2008 |
Hypothalamus Magnified |
| The slightly magnified view of the coronal image of a T2 weighted MRI shown above again shows the third ventricle in the midline (white). The thinnest inner layer is a mere pencil thin yellow line (paraventricular layer) and is barely seen even in this magnified view. The periventricular layer surrounds it. (orange)60528.8c09.8s hypothalamus brain pain autonomic nervous system parasympathetic nervous system sympathetic nervous system third ventricle 3rd ventricle periventricular nuclii optic tract pituitary paraventricular nuclii lateral nuclii medial nuclii optic tract MRI T2 weighted image Courtesy Ashley Davidoff MD copyright 2008 |
The Prefrontal Cortex |
| In this artistic rendering of the brain, the prefrontal cortex is outlined in light purple. The prefrontal cortex of the brain is the anterior part of the frontal lobes and is positioned anterior to motor and premotor areas. It is divided into the lateral, orbitofrontal and medial prefrontal areas, Functionally it is said to have executive function in that it orchestrates thoughts and actions, discriminates between good and bad, positive and negative . It is responsible for planning, cognitive behaviors, personality expression and moderating correct social behavior.
83029d.8s brain somatosensory cortex prefrontal cortex executive function The prefrontal cortex of the brain is the anterior part of the frontal lobes and is positioned anterior to motor and premotor areas. It is divided into the lateral, orbitofrontal and medial prefrontal areas, Functionally it is said to have executive function in that it orchestrates thoughts and actions, discriminates between good and bad, positive and negative . It is responsible for planning, cognitive behaviors, personality expression and moderating correct social behavior. Executive Function relates to abilities to differentiate among conflicting thoughts, determine good and bad, brain frontal lobe prefrontal cortex concious control thalamus basal ganglia caudate nucleus putamen globu pallidus operculum CTscan Courtesy Ashley Davidoff MD copyright 2008 The Common vein Davidoff art copyright 2008 |
Prefrontal Cortex |
| The axial or transverse CTscan of the brain taken at the level of the third ventricle. The prefrontal cortex is outlined in light purple.The prefrontal cortex of the brain is the anterior part of the frontal lobes and is positioned anterior to motor and premotor areas. It is divided into the lateral, orbitofrontal and medial prefrontal areas.
brain frontal lobe prefrontal cortex concious control CTscan Courtesy Ashley Davidoff MD copyright 2008 38568c02.8s |
The Prefrontal Cortex in Geographic Context |
| This transverse image of the brain at the level of the third ventricle and thalamus, is presented to show some of the structures discussed above in context to the prefrontal cortex dark pink or light purple). In this image, the thalamus (orange), Sylvian fissure (black), insular cortex (dark purple) and components of the basal ganglia (blue) are shown.38568c12.8s The prefrontal cortex of the brain is the anterior part of the frontal lobes and is positioned anterior to motor and premotor areas. It is divided into the lateral, orbitofrontal and medial prefrontal areas, Functionally it is said to have executive function in that it orchestrates thoughts and actions, discriminates between good and bad, positive and negative . It is responsible for planning, cognitive behaviors, personality expression and moderating correct social behavior. Executive Function relates to abilities to differentiate among conflicting thoughts, determine good and bad, brain frontal lobe prefrontal cortex concious control thalamus basal ganglia caudate nucleus putamen globu pallidus operculum CTscan Courtesy Ashley Davidoff MD copyright 2008 |