gray matter

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Human spinal cord

Understand the structure and functions of the central nervous system

gray matter

anatomy

Also known as: grey matter

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June 17, 2026

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Human spinal cord — Human spinal cord Lower cervical segment of the human spinal cord. In this photograph of a cross section, the white matter is shown stained dark.

Gray matter is a key component of the central nervous system, primarily found in the brain and spinal cord. It's characterized by its brownish-gray color and is composed of neural tissue, including nerve-cell bodies, nerve fibers, and glial cells. In the brain, gray matter forms the outer layer of the cerebrum, known as the cerebral cortex, which is responsible for higher intellectual functions, integrating sensory information, and directing motor activity. The cerebral cortex is highly convoluted, increasing its surface area.123

In the spinal cord, gray matter has a butterfly or H-shape and is surrounded by white matter. It contains cell bodies, unmyelinated motor neuron fibers, and interneurons. The extensive development of the cerebral cortex's gray matter is thought to distinguish the human brain from those of other animals. Gray matter is distinct from white matter, which consists of myelinated nerve fibers that insulate neurons.4532

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brain
…a convoluted (wrinkled) layer of gray matter. The degree of convolution is partly dependent on the size of the body. Small mammals (e.g., lesser anteater, marmoset) generally have smooth brains, and large mammals (e.g., whale, elephant, dolphin) generally have highly convoluted ones.
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…a convoluted (wrinkled) layer of gray matter. The degree of convolution is partly dependent on the size of the body. Small mammals (e.g., lesser anteater, marmoset) generally have smooth brains, and large mammals (e.g., whale, elephant, dolphin) generally have highly convoluted ones.
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cerebrum
…and an outer cortex of gray matter. The cerebral cortex is responsible for integrating sensory impulses, directing motor activity, and controlling higher intellectual functions. The human cortex is several centimetres thick and has a surface area of about 2,000 square cm (310 square inches), largely because of an elaborate series…
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…and an outer cortex of gray matter. The cerebral cortex is responsible for integrating sensory impulses, directing motor activity, and controlling higher intellectual functions. The human cortex is several centimetres thick and has a surface area of about 2,000 square cm (310 square inches), largely because of an elaborate series…
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prenatal development
Brain
The superficial gray cortex is acquired by the migration of immature nerve cells, or neuroblasts, from their primary intermediate position in the neural wall. The diencephalon is preponderantly gray substance, but its roof buds off the pineal gland, which is not nervous tissue, and its floor sprouts…
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The superficial gray cortex is acquired by the migration of immature nerve cells, or neuroblasts, from their primary intermediate position in the neural wall. The diencephalon is preponderantly gray substance, but its roof buds off the pineal gland, which is not nervous tissue, and its floor sprouts…
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medulla oblongata
… (white matter) and unmyelinated (gray matter) nerve fibres, and, similar to other structures in the brainstem, the white matter of the medulla, rather than lying beneath the gray matter, is intermingled with the latter, giving rise to part of the reticular formation (a network of interconnected neuron clusters within…
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… (white matter) and unmyelinated (gray matter) nerve fibres, and, similar to other structures in the brainstem, the white matter of the medulla, rather than lying beneath the gray matter, is intermingled with the latter, giving rise to part of the reticular formation (a network of interconnected neuron clusters within…
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nervous system
The vertebrate system
…and neuroglia predominate are called gray matter; areas in which myelinated neurons dominate are called white matter. Efferent, or motor, nerve fibres carry impulses away from the central nervous system; afferent, or sensory, fibres carry impulses toward the central nervous system. Visceral fibres innervate the viscera such as the heart…
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…and neuroglia predominate are called gray matter; areas in which myelinated neurons dominate are called white matter. Efferent, or motor, nerve fibres carry impulses away from the central nervous system; afferent, or sensory, fibres carry impulses toward the central nervous system. Visceral fibres innervate the viscera such as the heart…
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human nervous system
The spinal cord
The gray matter forms three pairs of horns throughout most of the spinal cord: (1) the dorsal horns, composed of sensory neurons, (2) the lateral horns, well defined in thoracic segments and composed of visceral neurons, and (3) the ventral horns, composed of motor neurons. The…
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The gray matter forms three pairs of horns throughout most of the spinal cord: (1) the dorsal horns, composed of sensory neurons, (2) the lateral horns, well defined in thoracic segments and composed of visceral neurons, and (3) the ventral horns, composed of motor neurons. The…
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