What is the Real Color of Nerves? The Answer Will Shock You

Delving deeper into the intricate marvels of the human body, we often encounter visual representations that simplify complex realities.

The Misunderstood Palette: What Color Are Your Nerves, Really?

The human nervous system, a marvel of biological engineering, is often depicted in diagrams and textbooks with a striking simplicity: nerves are typically rendered in bright yellow or sometimes even blue. This common visual shorthand, while useful for clarity in educational contexts, fosters a widespread misconception about the actual appearance of these vital communication pathways. It’s a vivid artistic interpretation, not a true-to-life representation, and it sets the stage for a surprising revelation.

The truth, however, is far more nuanced and, arguably, more fascinating than any simplified diagram suggests. The actual color of nerves in a living organism is not a uniform yellow or blue but a complex, varied spectrum influenced by multiple biological and observational factors. This "shocking" reality challenges our ingrained perceptions and opens the door to a deeper understanding of neural biology.

The apparent color of nerves is not merely a static property but a dynamic interplay of several key elements:

Biological Composition: The Intrinsic Hues

At their core, nerves are made of specialized cells, primarily neurons, and supporting glial cells. The specific components within these cells significantly contribute to their inherent color:

• Myelin Sheath: Many nerve fibers are wrapped in a fatty, insulating layer called the myelin sheath. This myelin is rich in lipids, which naturally appear off-white or yellowish-white. The presence of dense myelination is what gives “white matter” in the brain and spinal cord its characteristic pale appearance.
• Axons and Cell Bodies: The unmyelinated portions of neurons, including nerve cell bodies and unmyelinated axons, typically have a grayish or brownish-gray tint due to the absence of myelin and the presence of cellular organelles. This is the basis for “gray matter.”
• Neurotransmitters and Pigments: While not a primary determinant of overall nerve color, some specialized neurons contain specific pigments (like neuromelanin in certain brain regions) or dense concentrations of neurotransmitters that can add subtle hues.

Blood Supply: The Blush of Life

Like all living tissues, nerves require a constant supply of oxygen and nutrients, delivered through a dense network of capillaries and blood vessels. This vascularization plays a significant role in their appearance, especially in vivo:

• The presence of oxygenated blood can impart a reddish or pinkish hue to the surrounding nerve tissue.
• Areas with a particularly rich blood supply will appear more vibrant, while less vascularized regions might seem paler.

Visualization Techniques: The Observer’s Influence

Perhaps one of the most significant factors influencing how we perceive nerve color is the method used to observe them. There’s a stark difference between what nerves look like inside a living body versus how they appear in a lab specimen:

• In Vivo Observation: When viewed directly within a living organism (e.g., during surgery or advanced imaging), nerves retain their natural characteristics, including their vascularization and the inherent colors of their components.
• Preserved Specimens: For study, nerves are often removed from the body and subjected to preservation processes (like fixation with formaldehyde), which can alter their natural color, often bleaching them or causing them to become opaque. Furthermore, histological staining techniques are frequently employed to highlight specific structures, resulting in the vibrant blues, reds, and yellows we commonly see in microscopic images, which are artificial colors added for contrast.

Understanding these factors allows us to move beyond the simplified textbook images and appreciate the authentic visual complexity of the nervous system. To truly grasp this living complexity, we must first look at what nerves reveal themselves to be when they are alive and functioning within the body.

While our initial thoughts about nerve color might be influenced by the vivid depictions in textbooks, understanding their true appearance requires looking beyond the simplified diagrams.

Unveiling the Living Wire: What Nerves Truly Look Like Inside You

When we envision the intricate network of our nervous system, images of brightly colored anatomical models often come to mind—nerves depicted in stark yellow or blue, clearly demarcated against other tissues. However, the living reality of nerves within a functional human body, known as in vivo, presents a far more subtle and fascinating picture. They are not the vibrant, distinct structures often portrayed; instead, their true appearance is a testament to their delicate biology and vital function.

The Subtle Palette: Nerves in Their Natural Habitat

In a living, breathing human, nerves do not glow with primary colors. Instead, their natural coloration is remarkably understated, often appearing as a translucent, off-white, or slightly pinkish-gray. This subtle hue is largely attributable to two primary factors:

• Blood Supply: Nerves, like all living tissues, require a rich blood supply to function. A dense network of tiny blood vessels, known as vasa nervorum, permeates the nerve bundles, providing essential oxygen and nutrients. The presence of this blood, even in microscopic capillaries, imparts a faint pinkish or reddish tint that blends with the nerve tissue itself, contributing to the overall muted, flesh-toned appearance.
• Tissue Composition: The nerve fibers themselves, along with their surrounding cellular structures, reflect and scatter light in a way that results in this translucent, off-white quality. They are not opaque like muscle or bone, allowing some light to pass through and revealing the subtle underlying vasculature.

The Protective Veil: Connective Tissues

What we perceive as a "nerve" in the body is rarely just a solitary nerve fiber. Instead, nerves are complex bundles of thousands of individual nerve fibers, meticulously organized and encased by layers of specialized connective tissue. These protective wrappings are crucial for both the structural integrity and the functional health of the nerve, and they significantly contribute to its overall macroscopic appearance:

• Epineurium: This is the outermost, dense, irregular connective tissue layer that surrounds the entire nerve, encasing multiple nerve fascicles (bundles of nerve fibers). It provides robust protection and contains the larger blood vessels that supply the nerve. Its fibrous nature contributes to the overall off-white, slightly yellowish-white appearance of a major nerve trunk.
• Perineurium: Beneath the epineurium, each individual bundle of nerve fibers (a fascicle) is surrounded by the perineurium. This layer is composed of concentric layers of flattened cells that form a protective blood-nerve barrier, regulating the internal environment of the nerve fascicle. It has a slightly more translucent, glistening quality than the epineurium.
• Endoneurium: Within each fascicle, individual nerve fibers (axons) are enveloped by the endoneurium, a delicate layer of loose connective tissue. This innermost layer supports the individual nerve fibers and contains the capillaries that nourish them directly. It is largely transparent.

These connective tissue layers, collectively, give a nerve its palpable form and contribute significantly to its subtle, often fibrous, off-white or grayish-white appearance in the living body, rather than the intrinsic color of the nerve fibers themselves.

Beyond the Textbook: The Simplification of Models

The stark contrast between the in-vivo appearance of nerves and their representation in anatomical models or diagrams is striking. Models typically use bright, distinct colors—yellow, red, or blue—to highlight nerves, arteries, and veins, respectively. This simplification is not an oversight but a pedagogical tool. By assigning vivid, contrasting colors, models effectively:

• Enhance Visibility: They make it easier for students and practitioners to identify and trace the complex pathways of nerves amidst other tissues.
• Aid Differentiation: The distinct colors help to differentiate nerves from blood vessels, muscles, and bones, which in a real body, might all appear in shades of pink, white, and red.
• Simplify Learning: They reduce cognitive load by presenting a clear, albeit stylized, representation of anatomical structures.

However, it’s crucial to remember that these vibrant colors are an artistic and educational convention, not a reflection of the nerve’s actual color in a living organism. The translucent, off-white to pinkish-gray reality of in vivo nerves underscores their delicate, organic nature, subtly blending into the body’s intricate landscape.

This inherent translucence and subtle coloration provide a foundational understanding, but they don’t tell the whole story of nerve diversity, especially when we consider the significant role of the myelin sheath in influencing the color of specific nerve types.

After exploring the remarkable live architecture of nerves and their individual components, it’s natural to wonder about the distinct appearances they can present within the body.

The White Wonder: How Myelin Gives Nerves Their Distinctive Sheen

The vibrant, dynamic structure of nerves we observed in vivo only tells part of the story. When we examine nerve tissue, particularly in the brain and spinal cord, one of the most striking visual differences is the presence of areas that appear distinctly white, in stark contrast to the surrounding grey tissue. This pearly-white coloration is not random; it’s a direct result of a crucial component known as the myelin sheath.

What is the Myelin Sheath?

At its core, the myelin sheath is a specialized fatty, insulating layer that wraps around the axons of many nerve cells. Imagine it like the plastic insulation around an electrical wire; its primary role is to enhance the speed and efficiency of electrical signal transmission along the axon. This vital sheath is not part of the neuron itself but is formed by specific supporting cells in the nervous system:

• Schwann Cells (in the Peripheral Nervous System – PNS): These cells are responsible for forming myelin around axons in the nerves outside of the brain and spinal cord. A single Schwann cell typically myelinates only one segment of an axon.
• Oligodendrocytes (in the Central Nervous System – CNS): Located within the brain and spinal cord, oligodendrocytes are the myelin-producing cells of the CNS. Unlike Schwann cells, one oligodendrocyte can extend its processes to myelinate multiple segments of several different axons.

The Science Behind the White

The characteristic pearly-white color of myelinated nerve fibers is a direct consequence of the myelin sheath’s composition. Myelin is exceptionally rich in lipids (fats), making up about 70-80% of its dry weight, with the remainder being proteins. This high lipid content plays a critical role in how light interacts with the tissue:

• Light Reflection: Lipids, particularly the complex lipids found in myelin, are highly reflective. When light hits these fatty layers, it is scattered and reflected back, giving myelinated axons and nerve tracts their distinct white appearance. This is similar to how fat in meat or certain plant waxes can appear white or pale.
• Insulation and Speed: Beyond its visual properties, the fatty nature of myelin acts as an excellent electrical insulator. This insulation allows nerve impulses to "jump" along the axon from one unmyelinated gap (Node of Ranvier) to the next, a process called saltatory conduction. This dramatically increases the speed of signal transmission, often by a factor of 100 or more, compared to unmyelinated fibers.

Myelin and White Matter

The concept of the myelin sheath directly underpins the anatomical distinction of White Matter in the central nervous system. White matter, found abundantly in the deeper parts of the brain and throughout the spinal cord, is predominantly composed of bundles of these myelinated axons. These myelinated tracts serve as the brain’s high-speed communication highways, efficiently transmitting signals over long distances between different brain regions and between the brain and the rest of the body. Their collective white appearance is a testament to the sheer volume of myelinated fibers present.

To further understand the profound impact of myelin, let’s compare the key characteristics of nerve fibers with and without this crucial sheath:

Table 1: Key Characteristics of Myelinated vs. Unmyelinated Nerve Fibers

Characteristic	Myelinated Nerve Fibers	Unmyelinated Nerve Fibers
Appearance/Color	Pearly-white	Greyish
Myelin Sheath	Present	Absent
Conduction Speed	Very fast (due to saltatory conduction)	Slower (continuous conduction)
Energy Efficiency	High (less ATP used for ion pumping)	Lower (more ATP used for continuous ion exchange)
Location (General)	Predominant in White Matter of CNS, long-distance PNS nerves	Predominant in Grey Matter of CNS, shorter/local PNS nerves
Primary Function	Rapid, long-distance signal transmission	Slower, local processing and diffuse signal transmission
Insulation	High	Low/None

While myelin explains the dazzling white of certain neural pathways, it leaves us to ponder the other side of the spectrum: the enigmatic hues of grey.

While the brilliant white of myelinated nerves reveals one aspect of the nervous system’s intricate design, another crucial component unveils a more subdued, yet equally vital, color.

Decoding the Brain’s Palette: Unraveling the Mystery of Grey Matter’s Hue

After exploring the bright, reflective nature of myelinated nerve fibers, it’s time to delve into the other side of the nervous system’s spectrum: the captivating, somewhat understated, grey. This hue is not a uniform color but rather a visual aggregate of various neural components, primarily those that lack the fatty insulation we just discussed.

The Uninsulated Truth: Unmyelinated Nerve Fibers

Not all nerve fibers are cloaked in the brilliant white of the myelin sheath. Many, especially the thinner, shorter connections within the brain and spinal cord, operate without this insulating layer. These are known as unmyelinated nerve fibers. Because they lack the lipid-rich myelin, which is responsible for the white appearance due to its high fat content and light-scattering properties, these fibers do not appear white. Instead, their natural color is a more translucent, often faint pinkish-grey or tan, reflecting the color of the neuronal cytoplasm and the surrounding tissue. Without the reflective myelin, light passes through them differently, contributing to a darker, less bright appearance compared to their myelinated counterparts.

The Collective Canvas: What Makes Grey Matter Grey?

The ‘greyish’ appearance of Grey Matter is a fascinating composite. It’s not just the unmyelinated nerve fibers that contribute to this distinctive hue. Instead, it’s a rich tapestry woven from:

• Neuron Cell Bodies (Somas): These are the main "command centers" of neurons, where the nucleus and most cellular machinery are located. They are relatively dark and dense, contributing significantly to the greyish tint.
• Dendrites: These are the tree-like extensions that receive signals from other neurons. Like cell bodies, they are unmyelinated and packed with cellular components, adding to the overall grey appearance.
• Unmyelinated Nerve Fibers: As discussed, the axons that lack myelin sheaths also form part of this intricate network, blending into the background color.
• Capillaries and Glial Cells: A dense network of blood vessels (capillaries) and supporting glial cells (like astrocytes and oligodendrocytes, though the latter also produce myelin) are also present in grey matter, further influencing its overall color.

It’s the sheer concentration of these unmyelinated structures and cell bodies that gives Grey Matter its characteristic ‘dirty white’ or ‘greyish-brown’ color, often described simply as grey.

A Stark Contrast: Grey vs. White

The fundamental difference in appearance between Grey Matter and White Matter boils down to the presence or absence of significant myelination.

• White Matter: Predominantly composed of myelinated axons, which appear white due to the fatty myelin. These are like the high-speed data cables connecting different regions.
• Grey Matter: Characterized by a high concentration of neuron cell bodies, dendrites, and unmyelinated axons. This is where information processing, synaptic connections, and neural computations largely occur. The lack of extensive myelin is why it appears darker and less reflective.

This distinction is crucial for understanding brain function, as the grey matter is where much of the ‘thinking’ happens, while white matter serves as the communication network.

Prominent Locations of Grey Matter and Unmyelinated Nerves

Grey matter, with its rich density of neuronal processing units, is strategically located where complex computations are performed. Some prime examples include:

• Cerebral Cortex: The outer layer of the cerebrum, responsible for higher-level functions like language, memory, consciousness, and voluntary movement. It is almost entirely composed of grey matter.
• Basal Ganglia and Thalamus: Deeper structures within the brain that play vital roles in motor control, learning, and relaying sensory information.
• Spinal Cord Central Region: The H-shaped central core of the spinal cord is composed of grey matter, housing neuron cell bodies involved in reflexes and transmitting signals to and from the brain.
• Cerebellar Cortex: The outer layer of the cerebellum, crucial for motor control, coordination, and balance.

These regions, teeming with unmyelinated fibers and neuron cell bodies, are the bustling hubs of neural activity, visually distinct from the expansive tracts of white matter that connect them.

However, the true visual understanding of these structures often goes beyond their natural appearance, revealing further secrets under careful examination.

Moving beyond the subtle, inherent hues of living tissues like the grey matter and unmyelinated nerve fibers we explored previously, it’s crucial to understand that our perception of nerve color is profoundly shaped by the very techniques used to study them.

The Stained Truth: How Preparation Unveils and Alters Nerve Appearance

When you look at vibrant images of the brain and nerves in textbooks or atlases, you’re rarely seeing them in their natural, living state. Instead, these visuals are often the result of intricate scientific processes designed to preserve, section, and highlight microscopic structures. The journey from living tissue to a detailed anatomical image involves steps that dramatically alter the original color of nerves, making them visible and understandable in ways that would be impossible otherwise.

The Transformative Touch of Anatomical Preservation

The initial step in studying nerves outside the body, particularly for gross anatomical dissection, involves anatomical preservation. The most common technique is formaldehyde fixation. While this process is essential for halting decomposition and firming up delicate tissues, it also brings about significant chemical changes within the nerve tissue. Proteins within the nerve fibers undergo a process called denaturation, altering their natural optical properties.

As a result, the translucent, slightly off-white, or even faintly yellowish appearance that some nerves might have in vivo (in a living organism) is replaced. Fixed nerves typically appear opaque, becoming a dull, uniform pale yellow or off-white. This color change, while sacrificing natural vibrancy, ensures the tissue’s structural integrity for detailed study and handling during dissection.

Histology: Peering into the Microscopic World of Nerves

Beyond what can be seen with the naked eye during dissection, histology plays an indispensable role in understanding the intricate world of nerves. Histology is the microscopic study of tissues and their organization. For nerves, it involves taking tiny samples, processing them, and then cutting them into incredibly thin slices (often just a few micrometers thick). These delicate sections are then mounted on glass slides, allowing scientists to examine the cellular components—such as individual neurons, glial cells (support cells), and the myelin sheaths—at high magnification under a microscope. Without histological techniques, the fine details of nerve structure, which are crucial for understanding their function and dysfunction, would remain invisible.

The Palette of Precision: Unlocking Nerve Details with Stains

Even under a microscope, many cellular components are largely transparent. This is where histological staining techniques become vital. These specialized dyes bind selectively to different molecules and structures within the nerve tissue, imparting specific colors and creating contrast that allows for clear visualization and differentiation of various components.

• General Purpose Stains: Hematoxylin and Eosin (H&E): Often the first stain used, H&E provides a broad overview of tissue architecture. Hematoxylin stains acidic structures (like cell nuclei, which contain DNA) blue or purple, while Eosin stains basic structures (like cytoplasm and extracellular matrix) pink or red. In nerve tissue, this allows for a general appreciation of neuron cell bodies, their processes, and the surrounding tissue.

• Targeting Neuronal Bodies: Nissl Stains: Named after Franz Nissl, these stains (e.g., Cresyl violet or Toluidine blue) specifically target the rough endoplasmic reticulum (RER) and ribosomes within the cell bodies of neurons. These clumps of RER are known as "Nissl bodies." Nissl stains color these structures a distinct blue or purple, making neuronal cell bodies stand out prominently. This technique is invaluable for studying neuronal density, distribution, and changes in response to disease or injury.

• Illuminating Myelin: Myelin Stains: To visualize the myelin sheaths that insulate many nerve fibers, specific stains are employed. Luxol Fast Blue (LFB) is a popular example. LFB selectively stains the lipids within myelin sheaths a vibrant blue, while other tissue components remain unstained or are counterstained in a light pink. This allows researchers to clearly delineate white matter tracts (which are rich in myelinated axons) and assess the integrity of myelin, which is crucial for diagnosing conditions like multiple sclerosis where myelin is damaged.

It is through these precise staining processes that the "colors" of neuroanatomy are born.

Stain Name	Target Nerve Component(s)	Resulting Color(s)
Hematoxylin and Eosin (H&E)	Cell nuclei, cytoplasm, extracellular matrix	Nuclei: Blue/Purple; Cytoplasm: Pink
Nissl Stains (e.g., Cresyl Violet)	Rough Endoplasmic Reticulum (Nissl Bodies) in neuron cell bodies	Blue/Purple
Luxol Fast Blue (LFB)	Myelin sheaths	Myelin: Blue; Background: Light pink (if counterstained)

The Artifice of Appearance: Textbook Colors and Beyond

The vibrant blues, purples, and reds you encounter in neuroanatomy textbooks and atlases are, therefore, seldom the true in vivo colors of nerves. They are the carefully orchestrated results of these specialized staining processes. Far from being misleading, this ‘artificial’ coloring is a sophisticated scientific tool. It allows neuroanatomists and clinicians to differentiate between incredibly similar structures, identify specific cell types, track nerve pathways, and diagnose pathologies that would otherwise be indistinguishable. Understanding this distinction is key to truly appreciating the complexities of the nervous system as depicted in educational materials.

Grasping how these colors are generated is more than just academic curiosity; it’s a foundational step towards understanding why nerve color truly matters in the practical worlds of neuroanatomy and medicine.

While the previous section illuminated how methods like dissection, histology, and staining dramatically improve our ability to visualize the intricate structures of nerves, the journey into truly understanding nerve appearance doesn’t end there.

Decoding the Chromatic Clues: Why Nerve Color Is More Than Just a Shade in Neuroanatomy and Medicine

The color of a nerve, far from being a simple, fixed attribute, is a dynamic spectrum influenced by a complex interplay of intrinsic biological factors and extrinsic experimental manipulations. Appreciating this nuance is fundamental for anyone delving into the intricacies of human neuroanatomy and its clinical implications.

The Multifaceted Nature of Nerve Coloration

The perceived color of a nerve is not determined by a single element but by the combined effect of several key components:

• The Myelin Sheath: Perhaps the most significant determinant of nerve color, the myelin sheath is a fatty, insulating layer that wraps around many nerve fibers. This high lipid content gives myelinated nerves their characteristic whitish or pale appearance, leading to the well-known distinction between the "white matter" (rich in myelinated axons) and "gray matter" (consisting mostly of nerve cell bodies and unmyelinated axons) of the brain and spinal cord. The thicker the myelin, the whiter the nerve often appears.
• Blood Supply (Vascularity): Nerves, like all living tissues, require a robust blood supply to function. The presence of numerous capillaries and arterioles within and around nerve bundles can impart a reddish or pinkish hue, especially in fresh tissue. Highly vascularized nerves will naturally appear redder than those with less blood flow.
• Surrounding Connective Tissue: Nerves are not isolated fibers; they are encased and supported by layers of connective tissue (epineurium, perineurium, and endoneurium). These fibrous sheaths, while often translucent or whitish themselves, can contribute to the overall texture and opacity, subtly influencing how light interacts with the nerve and thus its perceived color.
• Preservation and Staining Methods: Once removed from the body, the appearance of nerve tissue changes dramatically.
  • Fixation: Chemicals like formalin, used to preserve tissue, can cause discoloration, often a grayish-brown.
  • Staining: In histology, specific dyes are applied to highlight different components. For instance, myelin-specific stains like Luxol Fast Blue will turn myelinated fibers blue, while Hematoxylin and Eosin (H&E) will stain cell nuclei purplish-blue and cytoplasm pink, providing a different perspective on nerve structure.

A Spectrum, Not a Single Shade

Given these variables, it’s crucial to understand that nerve color is not a static, universally agreed-upon descriptor. Instead, it represents a continuum of appearances that can shift based on:

• Location: Nerves in different parts of the body or within different regions of the central nervous system may have varying myelin content, vascularity, and connective tissue support, leading to distinct natural colors.
• Physiological State: A nerve’s color can even subtly change based on its metabolic activity or immediate blood flow.
• Preparation: The vast differences between fresh, living tissue, embalmed cadaveric tissue, and meticulously stained microscopic slides underscore the variability in perceived nerve color.

Diagnostic Clues from Altered Nerve Appearance

Beyond academic understanding, the visual characteristics of nerves hold significant diagnostic importance in medicine. Changes in nerve appearance can be vital indicators of disease processes:

• Demyelinating Diseases: Conditions like Multiple Sclerosis (MS) involve the destruction of the myelin sheath. Affected areas of the brain or spinal cord will lose their characteristic white appearance, becoming paler or more translucent due. Clinicians and pathologists can often identify these lesions based on their altered coloration in MRI scans or upon gross examination of tissue.
• Ischemia and Hemorrhage: Reduced blood flow (ischemia) or bleeding (hemorrhage) can lead to changes in nerve color, from pallor to dark discoloration, indicating tissue damage or compromised viability.
• Tumors and Inflammation: Pathological growths or inflammatory processes can alter the normal architecture and vascularity of nerve tissue, leading to visible changes in color and texture that aid in diagnosis.

Enriching Our Understanding of Neuroanatomy

By appreciating the nuanced factors that contribute to nerve color, we move beyond a simplistic view of the nervous system. This understanding enriches our grasp of human neuroanatomy, allowing us to:

• Interpret images more accurately: Whether viewing gross dissections, MRI scans, or histological slides, recognizing the origins of different hues provides deeper insights.
• Connect structure to function: The whiteness of myelin immediately brings to mind its role in rapid signal conduction, while the vascularity hints at the metabolic demands of nervous tissue.
• Recognize pathology: Identifying subtle deviations from normal nerve coloration becomes a critical diagnostic skill, aiding in the early detection and understanding of neurological disorders.

Understanding the dynamic nature of nerve color, therefore, is not merely an anatomical detail; it is a fundamental aspect of comprehending the intricate workings of the nervous system and interpreting its health and disease states. This foundational appreciation prepares us to delve even deeper into the unfolding complexity of nerve color.

Our journey through the nervous system has revealed that the answer to, “What color are nerves, really?” is not a simple one. We’ve uncovered that a living nerve, with its rich blood supply, presents as a pearlescent, pinkish-gray, while the fatty myelin sheath gives White Matter its characteristic hue. We’ve seen how the absence of this sheath defines the color of Grey Matter, and how the processes of dissection and histological staining create the vibrant, yet artificial, colors we see in textbooks.

Ultimately, the color of a nerve is not a fixed attribute but a dynamic spectrum, a testament to its biological context and the lens through which we observe it. Understanding this complexity does more than satisfy curiosity; it deepens our respect for neuroanatomy and highlights how altered appearances can signify disease. The next time you see a diagram of the nervous system, you’ll know the incredible, multi-hued reality hidden beneath those simple lines—a true reflection of the profound and intricate design of our body’s command center.