Tag: The Common Vein

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BEYOND THE WATER DROP

BEYOND THE WATER DROP

From Big Bang to Eternity –

From the explosive womb of Big Bang
Hydrogen, your progenitor was born
Consisting of single moving and opposite forces
Seeking companionship, and a need for Oneness
Bigger and more powerful than the self
And the atoms and elements and then the molecules of life
Were themselves given life

And then you my darling water
The purest of beings

Born with a gush from the amniotic sacs of Big Bang
Finding your way to virgin earth
Under forces beyond you
With forces in you
To enable all of life
For without you we would not be

The single droplet of rain hitting the puddle
With its kind but explosive kinetic force


Under the same original force that brought you to earth
Converting to a beautiful sound of the droplet on water
With an array of waves in perfect circle

As I ponder this wonder
The beauty of physics at its best
No energy destroyed, just converted
A simple yet not so simple action reaction of Newton
Snow, ice, vapor, waves of the sea, and a flowing river

Calming of the soul
Giver of life
From Big Bang to Eternity

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We the Cells of the Body, Want to Create a More Perfect Union

Adam and Eve Choose Cabinet Members for the Body’s Society of Cells

Arielle Davidoff and Ashley Davidoff  Copyright 2017

 Look deep into nature and then you will understand everything better – Einstein 

As Adam and Eve entered the Garden of Eden they heard the cry of the disparate cells of the body:

“Without each other we are nothing.  Please unite us in structure and function with your wisdom. E Pluribus Unum!”

E Pluribus Unum – Out of Many, One

The cells knew they would be around for a long time; their grand scheme was to pursue Oneness. They understood the consequences of bullying, selfishness, greed, and jealousy. They also knew the power of goodness, integrity, humility, and sharing.  The cells resolved to fight the evil aspects of humanity.  56 cells from all walks of life discussed the issue of collaborative community living, and drafted a constitution they all signed in Philadelphia.  The cells submitted this proposal to Adam and Eve. It read:

“We the Cells of the Body, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United Cells of the Body.”

50 representative cells overlying the stars

Adam and Eve realized that the cell was the key “person” in their society 

Adam and Eve, taken aback by the wisdom of biology, accepted the proposal and recognized the document as a marvel of humanity.  They knew it was imperfect, but accepted that as humanity learned through time, experience, and application, it could be amended and better understood.

And so what to do now?

Adam and Eve’s first task was to choose leadership for this noble effort.  Which type of cells did the society of the body need? The stakes were high; they needed to organize an efficient society in which each of the body’s 37.2 trillion individual cells would be fed, protected, fulfilled and free.  In the Garden of Eden, Adam and Eve examined the variety of cells that surrounded them, then turned to consider the needs of society. thinking about which to choose.

Essential Functions

They debated and discussed how to build a body to house and protect its contents and enable the person to live a full and free life.  They spoke through the night and on the sixth day they arrived at a basic plan of a successful body’s most important functions. Those functions would fulfill the direction of the constitution they had drafted earlier.

Their plan was a simple list of the body’s essential functions:

  1. control, manage, direct
  2. protect and support
  3. provide food, energy, and manufacture needed products
  4. transport
  5. maintain
  6. produce and prepare the next generation

In the Garden of Eden, Adam and Eve entered the society of the cells and began to select societal leaders for the various essential functions on their list.

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Adam and Eve in the Garden of Eden’s Cell Shop

 Adam and Eve ventured into the Garden of Eden Cell Shop with their shopping list of the functional needs for their society.

Finding the Leader Cell to Control, Manage and Direct

The cell to govern the body would need an overview of the whole situation of life and Oneness.  Its chief characteristics would be wisdom, honesty, humility and integrity. It also needed to sense and react appropriately to both the external and internal environment so that everybody could live a safe and fulfilling life. This cell also had to be able to communicate with every cell in the body – all 37.2 trillion of them – from the tip of the head to the tips of the toes.

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The Neuron – “Il Presidente”

They chose the brain cell or neuron for its leadership, and they playfully called  it “Il Presidente.”  Crucially, the neuron could connect not only with other brain cells, but also (directly or indirectly) with every cell in the body. The neuron could also react to the outside environment.

Adam and Eve Trying on the Brain Cell for Size

 Adam tried on the brain cell and sought Eve’s approval.  It was tailored for both the internal and external environments.

Modified public domain work of Henri Rousseau “The Dream”  1910 (MoMA)

“Il presidente” made his first speech referencing Hillel’s sage advice: “If I am not for the body of my person who will be?  And if I am only for the body of my person, then what am I?  If not now when then?”

Adam and Eve nodded at each other, satisfied with their choice.

Finding a Cell for Protection  

Adam and Eve lived in a dangerous environment.  Wild, predatory animals ranged in size from the dinosaurs to violent religious zealots, to the smallest virus particles.  They identified two principal needs – protection from the outside, and protection from the inside of the body.  They turned first to secure internal security.

Adam and Eve were aware of Voltaire’s wise words: “Beware of the words ‘internal security,’ for they are the eternal cry of the oppressor.”  They also knew, conversely, that Cicero stated “Salus populi suprema lex esto”  –  “Let the good (or safety) of the people be the supreme (or highest) law.”

The cell responsible for internal environmental control had to be highly intelligent, so it could sensitively identify the enemy without racial profiling.  Adam and Eve searched for a long time before they encountered an amazing, introverted cell genius, decorated with Einstein’s hairstyle. They called it the macrophage.  This cell had an exquisite memory for detail and an uncanny ability to spot and destroy the enemy of peace.  Rebels and terrorists in the body were no match for this cell.

 

The Macrophage Police Cell with a Crazy Hairstyle

The macrophage’s motto was the simple equation:   E = mc2

Enemy of the Common Good will be taken down by the Macrophage with Great Conviction for the sake of the peace of humanity

Finding a Cell to Manufacture Food, Energy, and Other Needed Products

The manufacturing function related to internal economy.  Adam and Eve knew that a successful internal economy required self sufficiency. All able bodied cells had a right and an obligation to work.  Adam and Eve remembered and appreciated the wise words of the famous John Kennedy who declared “My fellow Americans, ask not what your country can do for you, ask what you can do for your country.”

The body would need manufacturing facilities present in all of its parts.  Noticing, however, that the liver cell proved especially adept at manufacturing, Adam and Eve chose this cell to lead the body’s internal economy.

The Liver Cell – Key in Metabolic Function in the Metabolic Warehouse of the Body

 

Finding a Cell to Lead the Transport Function

Transport to and from the cells would be an essential bodily function.  Adam and Eve chose the red cell to lead the effort, since it could transport oxygen and carbon dioxide, which they knew is vital to life.  The red cell with its colorful hemoglobin was a natural choice.  They recognized its ability to rapidly exchange gases in the lungs and at the cell as a stunning accomplishment of nature.

Red Cell with Hemoglobin Responsible for the Transport of Oxygen and Carbon Dioxide

Finding the Cell to Lead Maintenance: Repair, Cleaning and Waste Removal 

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Stem Cell Maintenance and Repair

The stem cell can magically transform into many different types of cells necessary to repair and regenerate tissues, which can wear over time. Timed cell death, or apoptosis, is natural and regeneration is necessary. The adult stem cell is responsible for regeneration of blood cells, endothelia of blood vessels, and epithelia of skin, intestine, and respiratory tract.  Adult stem cells also repair tissues such as bone, cartilage, and non-cardiac muscle, which are prone to injury due to physical activity.  Adam and Eve chose the multipotential adult stem cell to maintain the body’s cell populations.

Preparation for the Next Generation 

The miracle of creation understood the importance of education.  Each generation would advance to wholeness only if it learned from the experience of prior generations.  Humanity has preserved history in archives, museums, and libraries.  Similarly, within the nucleus of each cell lies the accumulated experience of the generations in the library of the DNA.  Every cell contains all this valuable information, which continues to evolve as human experience advances.

The Library of Accumulated Experience in the Nucleus of the Cell
Courtesy of photograph provided by Ralf Roletschek / fahrradmonteur.de subsequently modified 

Best for Last: Reproduction

Nature drives men and woman together with the most pleasurable and profound experience to enable e plurabus unum of the female egg and male sperm.  The mechanical union is infused with a miraculous spark of life that enables the continuation of the species.
Sperm and Egg Meet and a Miracle (not to be taken for granted) Occurs
Adam and Eve rested, exhausted in each other arms, assured that the wonderful human experiment had begun.

And the next day…

…there was a meeting of the minds on the palace lawn.

 7 Cabinet Ministers Posing in Front of Government Center

The 7 cells chosen by Adam and Eve to  to advise the design of the structure and function of the body.

From left to right; Liver cell (manufacture), Macrophage (defense and protection) Ovum (reproduction) Neuron (government) Sperm (reproduction) Stem cell (maintenance and repair) and Red cell (transport)

 

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The Common Vein: Anatomy of Structure – Units and Connections

Structure – The First Step

Structure is a material unit or object, composed of smaller parts that are connected and organized so that it can stand alone but also  be part of a larger and more complex whole

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The Units That Make the Whole – The Brick and the Brick Principle

The brick is the unit that is the basis of the brick building.

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The Brick – An Individual Unit That Needs to Connect In Order to Function and Be Valuable

The brick by itself has no function and no value to the world.  In order to have value it needs to connect with other bricks.  When the brick, a structural unit,  connects with other bricks and they organize, a wall is built. The wall as a structural unit, connects with other walls and they organize to form a room, and eventually a building is built.  Although the brick is nothing by itself – a weak brick can bring the whole wall and the whole building down.

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The Power of the Brick

It is Nothing by Itself  

However the Whole is Only as Strong as the Weakest Brick

The Units That Make the Body – The Cell and the Brick Principle

I am like a brick. Amrish Puri

The cell is the unit that is the basis of biology.

cell, cells, liver, process, physiology, function, receive, process, produce, export, principles, nucleus, cytoplasm, cytology, anatomy, art, the common vein, art in anatomy, Ashley Davidoff MD

The cell by itself has no function nor value, unless it is a unicellular organism.  In order to have value it needs to connect with other cells.  When the cell, a structural unit,  connects with other cells and they organize, a tissue is built. The tissue as a structural unit, connects with other tissues and they organize to form an organ, and eventually a body is built.  Although the cell is nothing by itself – a weak cell can bring the tissue and the whole body down.

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When the 37.2 trillion cells in the human body connect and organize, they create a spark of life housed in the body and gifted with a mind.

The difference between the brick building and the person is really the life that biology brings.  It is truly a miracle and the secret of how this happens still eludes human endeavour.  This secret may never be unlocked.

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Subtract The Bricks From the Cells.  What is the Result?

What is very clear, is that as human biologic units build, the  result is larger and more powerful than the individual parts.  At a critical number a spark of life emerges within the body, and a mind emerges from both of them.  When and how that happens remains a mystery.

Our first project is not to delve into the yet unanswerable “hows” of life, but rather into the “hows” of structure.  Structure is complex, but the pattern of units connecting and organizing is universal and permeates structure from the  subcellular level to the whole body and even beyond into our communities.

Some Quotes About the Brick Principle

 “A great building will never stand if you neglect the small bricks.”

Ifeanyi Enoch Onuoha

“Love is like a brick. You can build a house, or you can sink a dead body.” Lady Gaga

“Brick and blood built Astapor, and brick and blood her people.”
George R R Martin – A Storm of Swords

14. “Genius too does nothing but learn first how to lay bricks then how to build, and continually seek for material and continually form itself around it.Every activity of man is amazingly complicated, not only that of the genius: but none is a ‘miracle.”
Friedrich Nietzsche

“I fear that in this thing many rich people deceive themselves. They go on accumulating the means but never using them; making bricks, but never building.”
George Eliot

“Faith. Trust. They don’t come naturally, but as we lay those first bricks, we notice that little by little, a foundation is forming. Eventually we can end up building the most beautiful things with faith and trust.”
José N. Harris

“Bricks without straw are more easily made than imagination without memories.”
Author: Lord Dunsany

“It takes a thousand bricks to build a wall, but only one to tear it down.”
Markus W. Lunner

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The Common Vein: Clarity in Complexity

Introduction 

The Common Vein (TCV) is a learning process that clarifies the complexities of biology and medicine.

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Complexity is the prodigy of the world.

Simplicity is the sensation of the universe.

Behind complexity, there is always simplicity to be revealed.

Inside simplicity, there is always complexity to be discovered —

                                                                                                                        Gang Yu

The Common Vein is a tree of knowledge that brings simplicity to the complexity of human biology and medicine.  Its arborized organization enables a stepwise, progressive approach to self learning.  Any student who can read, and who is motivated, will advance through this rich network of material. Most principles begin with a simple word or concept, within which resides encyclopedic complexity.  The root elements of that word can be explained in a sentence, which then progresses in volume and complexity to a paragraph, then a chapter, then a book, and beyond.

Imagine a library with all of its books strewn over the floor.  It would be nearly impossible to navigate the available information. Efficient organization of information is the key to understanding it. This concept holds true in any field of education.

Organizing Information

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From a Background of Complexity to an Organized Simplicity 

The above art-piece shows a background of extensive, pixellated, and seemingly inaccessible information. As it organizes into the central, conical figure, it begins to make sense. The word at the bottom of the cone becomes defined into its key elements (the 5 different colors of the circle).  A definition follows, which succinctly describes the essence of those principles. These elements advance to greater complexity at the next level: the paragraph.  Each elemental principle is further expanded in a chapter.  The ladder of organized information progresses, while remaining connected to its source. Roots and branches, origins and growth, are recurring themes in The Common Vein.

As we learn, we acquire new knowledge. At the same time, we modify and enhance preexisting knowledge. Education should therefore be viewed as a process, rather than a collection of facts (Learning Wikipedia). TCV’s cumulative approach reinforces previous knowledge as it advances existing knowledge. With the understanding that memory and its application are so key to the learning process, TCV encourages beginning with the roots (basics) and building to the branches (details) in a logical fashion.

The Tree of Knowledge

Below is a diagram of knowledge in its bare form. From the central trunk extends an arborising framework, from roots to branches, which represents advancement, or growth.

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Roots and Branches: Sources and Growth

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Roots and Branches: Sources and Growth – Advancing Complexity

The trunk reflects a single idea or concept (tree), which is part of a continuum belonging to something beyond it (branches) and something before it (roots).  The tree’s roots and branches again exemplify the concept of building upon previous knowledge.  The trunk’s extensions, in the form of roots and branches, are complex yet logical in their organization. A tree’s growth is multifaceted, yet progressive. The parts work together for the sake of the single element: the tree. In the tree, complexity and simplicity coexist.

Principles

A distinct focus on principles, especially as a starting point, provides a useful framework for learning. The Common Vein’s is founded upon principles that grow in complexity, which helps the student navigate the daunting mass of biological and medical information.

Principles of Human Biology

The image below diagrams human biology in its basic parts:

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This diagram of human biology is structurally identical to the diagram above. This diagram shows that the roots of human biology lie in both the structural and functional sciences. Combined, those two sciences enable the miracles of the working body and working mind. This simple diagram captures the entirety of human biology. Beyond these base elements lies magical complexity, which we can never fully grasp.

Principles of Medicine

This diagram, again identical in structure to the two above, explains that the roots of human disease originate in the disorder of the structural and functional sciences. The branches of diagnosis and treatment have evolved in response to the need for order and health of the body and mind.

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This tree illustrates The Common Vein’s central theme. Each biological part has both a structure and a function.  When they are in order and work cohesively, there is health.  With disorder, conversely, comes disease. The field of medicine attempts to bring order using two major disciplines: diagnosis and treatment.

Because roots and branches remain connected, a change in one element means a consequence in the others. The disciplines of diagnosis and treatment are founded upon the ability to identify and treat disordered structure and function. For example, an obstructed coronary artery causes a heart attack.  The clot in the artery causes a structural problem, with a the functional consequence (damaged heart muscle).   Coronary arteriography diagnoses the structural abnormality, and a cardiac echocardiogram diagnoses the functional consequence (decreased muscle contraction).  The treatment aims to reverse the structural abnormality by dissolving the clot, as it also aims to reverse the functional abnormality.

The Common Vein

The Common Vein finds clarity in complexity. It navigates the learner through complex information in order to understand, remember, and apply the knowledge.  Two major elements are used:

  1. Basic principles, which are connected and advanced through
  2. An arborised organization.

The “common” in the common vein refers to basic principles, while the “vein” represents the arborised connections creating a tree of knowledge.

Learning starts from the most basic element, and with careful progression, advances in detail.  Learning evolves over time, as it builds upon and enhances previous knowledge. The tree’s roots of knowledge reflect the learner’s existing knowledge. They are connected to the branches, which symbolize the paths of growth.

The Common Vein requires requires the ability to read, and passion for the subject material. With those, the whole field of biology and medicine opens up, and eventually, students learn to apply this network of knowledge as thoughtful thinkers and practitioners.

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Pain, Pain -Go Away!

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You came with no warning and no invitation

You came with a single message of doom and gloom

I had no control

It was fate

It was no joke

I had to take you seriously

You seem to be endless and to be going nowhere

With the unintended intention to taunt and haunt me

You are the source of my suffering.

Since the dawn of man

You have accompanied us with a not so gentle reminder

That everything is not OK

Some say you are protective

But it is sometimes hard to understand

All I know is that I suffer

Nociceptors sense the feeling

They come in different forms

Transmitting pain from pressure, prick, or improper heat,

– or a severe lack of it

Quickly the sensation travels

On the A, delta, or C train-

 Impulses that run their course

From source to spinal cord

With sizzling hot news of my experience

Where they snap to a halt as they clap as a synapse

And get a second order of direction

At the gate of decision

Which waves them on to a new thoughtless action

On their way to master control.

And through and via the wire of the RAS

Which awakens an awareness of you;

And then to the thalamic relay

Where they get their new orders:

To whom they should turn

And what direction to take.

In the higher levels of limbic autonomic and homunculus centers

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The sense becomes real

And the feeling becomes severe

And after all the science

I know not what to do

But to increase my heart rate a little,

Contract a muscle and a gland or two

And perhaps let out a scream at the height –

And impugn your intrusive impudence that imposes on me.

pain, nociceptor, poem, prayer, sensory system, thalamus, A fiber, delta fiber, C fiber, Ashley Davidoff MD. The Common Vein, Art in Anatomy

 And then sometimes

We use the eyes and guise

Of X-ray Eyes

Or try a tincture of opiate

To extirpate the excruciate –

And then sometimes to no avail

Yet I could care less about your wonderful pathways of biology and science

I know that I hurt -but also in a different way

It is not only the pain that I feel

But the pain of fate as well

That was handed to me as a card in a bad deal of nature

And I have no choice but to deal with it …..

But it hurts!

person, old lady, emotional pain, aging, poverty, loneliness

 

 

See the BLOG about the Art and Science of Pain

The Common Vein Copyright 2017

Ashley Davidoff MD

Revised since publication as a Blog August 2016

 

 

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Pain – Art and Science

Pain

Pain is an unpleasant  sensation originating from our physical and or emotional environments.

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Faces of Pain

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Extreme Physical Pain

 

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Extreme Emotional Pain

Physical Pain

Pain is a symptom and as such reflects a derangement of either the external or internal environment.

All sensations start by stimulating a receptor of  a nerve that conducts the impulse to the spinal cord where low level control and discrimination occurs, and transfers  the stimulus to the brain, where higher centers process the stimulus and react to it.  The structures in the brain include the thalamus, somatosensory cortex, limbic system, and autonomic systems and they are involved in  perception, localization and integration.  They send out a stimulus with instructions of how to react which is executed by muscle contraction or tissue secretion.

Functionally, pain is protective. The physiology and pathophysiology relate to changing the mechanical stimulus into an electrical impulse, and then through a series of complex synapses the stimulus is transmitted with the intent of  protecting the person from further damage.

The causes of pain are innumerable and exist within the full spectrum of human diseases. Pain may result from pain receptors sensitive to pain, (pricking, cutting, tearing) extreme temperatures, pressure, or aberrant chemical environments. A myriad of processes then occur in response to tissue injury causing either irritation of a somatic nerve or distension and pressure on a visceral sensory nerve. Inflammation is one of the most common of these injurious processes that is classically and universally expressed with  pain – a concept first described by the second century philosopher Celsus.

The result of a pain impulse is usually withdrawal from the insulting stimulus, resting of the injured part, or seeking the help of a medical practitioner if the pain is unbearable and arises from an internal disorder.

Diagnosis of pain disorders should proceed with careful history taking and clinical examination, followed by appropriate laboratory tests, and imaging if necessary.

Pain is a very common symptom and most instances are treated with an analgesic or antiinflammatory agent.   For more serious pains, treatment is directed at the cause of the pain.

Classification

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The table explores the variety of ways of classifying pain.  The left hand column reveals the classification based on functionality, origin, mode of stimulation, pathological causes and relationship of pain to chronicity.  As for functionality it may be adaptive or nonadaptive.  The pain may originate from somatic or visceral nociceptors, may originate from damaged nerves in which case it is called neuropathic, or it may be psychogenic.  The causes are usually via the inflammatory process but may result from any of the disease listed.

Structural Basis of Pain

A pain impulse is initiated by sensory receptors called nociceptors which are located in almost all the tissues. A noxious stimulus say from a hand touching a hot stove is then transmitted by sensory nerves to the spinal cord where a direct spinal reflex causes immediate withdrawal from the source. Additionally the stimulus is modified in the spinal cord by a variety of influences from other sources and is then transmitted via the midbrain and reticular activating system to the cortex. Finally, the stimulus reaches the brain’s somatosensory area where it is perceived and localized with additional extension to other areas of the cortex for the provision of a variety of protective reactions to the stimulus.

We will now expand the detail of the structural pathway described above.

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Pain from the Joints

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Pain from Sinuses 

The Sensory Pain Receptors – Nociceptors

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Nociceptor

A pain impulse is initiated by sensory receptors called nociceptors which are located in almost all the tissues. They are tree like branching structures.

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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.

 These specialized receptors vary in structure and number throughout the tissue and viscera of the body. There are external nociceptors that are situated in the skin and cornea with higher concentrations in the coverings of the body including the skin, pleura, pericardium, peritoneum and periosteum. Internal nociceptors are found in muscles, joints, around blood vessels, and within the mucosa of some organs including the urinary bladder, genitourinary tract, and the gastrointestinal tract. There are nociceptors in varying concentrations in almost every organ in the body, but interestingly there are none in the brain substance itself .

First Order of Transmitting Sensory Fibers 

The first order of nerve fibers transport the stimulus from the nociceptor to the dorsal root ganglion

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The sensory receptors of the nociceptors are found in the tissues peripherally 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. 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 30-100 meters per second

The Dorsal Root Ganglia

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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.

2nd  Order of Neurons

The second order sensory fibers are those fibers in the spinal cord.  They first cross to the contralateral side of the spinal cord and then connect to the thalamus via the spinothalamic tract. 

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Second Order Neurons  – Cross Over in the Spinal Cord and 3rd order are Found in the  Spinothalamic Tract 

The spinothalamic tract is the major sensory ascending pathway of 2nd order neurons and serves as the major pathway for pain, temperature, itch and crude touch. Within its construct, the spinothalamic tract has three merging bands of specialized fibers that conduct pain impulses. The anterior spinothalamic tract carries pain signals initiated by touch while the lateral spinothalamic tract carries slow and fast fibers for pain and temperature sensations. The anterolateral spinothalamic pathway, located in the anterolateral white column pathway in the anterior half of the lateral funiculus conducts a variety of somatic pain signals.

3rd  Order of Neurons – Connect the Thalamus with the Sensory Cortex

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The Three Orders of Neurons

Second Order Neurons From the Spinal Cord to the Brain and Perception of the Pain  The Three Orders of Neurons

 The stimulus is first converted into an electrical impulse which is taken by a first order sensory nerve (orange)  to the spinal cord (dorsal root ).  The second order neurons (blue) first transport the stimulus to the contralateral spinothalamic tract  which in turn transports the impulse  to the thalamus,.  The third order neurons (pink)  transport the impulse to the somatosensory cortex.

Role of the Thalamus

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Thalamus – Relay Station to the Cortex in the Pain Pathway
The thalamus (T) is the gateway to the cerebral cortex. It is a paired organ and represents the main part of the diencephalon and subserves both motor and sensory function. It is structurally and functionally situated between the cortex and the midbrain. The thalamus has specific nuclei with diffuse projections to and from multiple regions of cerebral cortex.  The thalamus functions as a translator for the cerebral cortex. It processes sensory and motor information and mediates the autonomic nervous system regulating sleep and arousal. The thalamus also contains reciprocal connections to the cortex that are involved in consciousness. It may also play a role in vestibular function.  The thalamus translates pain signals of the 2nd order neurons and gives rise to the third order neurons that extend to the cortex. Awareness and localization of the pain is then achieved at the level of the cortex. The thalamus however is not merely a relay station for nociception but also plays a role in processing the stimulus.  Axons terminating in the lateral thalamus mediate discriminative aspects of pain (somatosensory cortex) including the originating body part. The fibers ending in the medial thalamus mediate the motivational and affective aspects relating for example to the emotional and memory of pain. These third order neurons travel to the prefrontal cortex, insular and cingulate gyrus which contribute to the emotion and memorization of pain experiences. 

The Homunculus Man and Localization of the Pain 

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HOMUNCULUS MAN and Localization of Sensation in the Somatosensory Cortex of the Parietal Lobe

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. The diagram reflects the relative functional sensory space each body part occupies in the somatosensory cortex. 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. Nerve fibers from the spinothalamic tract in the spinal cord (blue line) are relayed to the thalamus (orange) which filters and then distributes the sensation to the somatosensory cortex.

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The Somatosensory Cortex in the Parietal Lobe – Home of the Sensory Homunculus

The somatosensory cortex in the parietal lobe  is the location of the the main sensory receptive area for all the senses including pain. It receives the stimuli from the thalamus and then integrates the information with other parts of the brain  that will modify the perception of the sensation

The function of the somatosensory cortex is that of a higher processing center for touch, temperature, pain, and proprioception serving to amplify awareness of the sensations enabled by the thalamus. Sensation from the left side of the body are processed in the right somatosensory cortex and similarly those from the right side are processed on the left. The higher function of the somatosensory cortex allows us to localize the pain to a specific site, perceive the character and intensity of the stimulus, and sometimes helps identify the shape of the originating object.

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The Higher Multicentric Levels of Pain Perception and Reaction

The somatosensory cortex relays impulses to other cerebral areas of perception that modulate the reaction to the pain  It forward the pain signals via the white matter to other centers in the cortex to enable integration with visual and auditory input, and with other higher cortical functions such as emotion and memory for example. The full experience is then “seen” by the brain enabling the consequent reaction to be as discriminating  and prudent relative to the nature and experience of the person. The difference between the reaction of an infant, child and an adult to the “shot at the doctors” speaks volumes about this latter function. 

Emotional Pain

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Pain of Poverty

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Pain of Addiction

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Pain of Loneliness

Pain .. Pain go away! – and please leave us alone!