The dorsal root of spinal nerve (or posterior root of spinal nerve or sensory root) is one of two "roots" which emerge from the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spin ...

. It emerges directly from the spinal cord, and travels to the

dorsal root ganglion A dorsal root ganglion (or spinal ganglion; also known as a posterior root ganglion) is a cluster of neurons (a ganglion) in a dorsal root of a spinal nerve. The cell bodies of sensory neurons known as first-order neurons are located in the dor ...

. Nerve fibres with the

ventral root In anatomy and neurology, the ventral root of spinal nerve, anterior root, or motor root is the efferent motor root of a spinal nerve A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cor ...

then combine to form a spinal nerve. The dorsal root transmits sensory information, forming the

afferent Afferent may refer to: Anatomical structures Meaning "conveying towards a center": * Afferent arterioles, blood vessels that supply the nephrons * Afferent lymphatic vessels, lymph vessels that carry lymph to a lymph node * Afferent nerve fiber ...

sensory Sensory may refer to: Biology * Sensory ecology, how organisms obtain information about their environment * Sensory neuron, nerve cell responsible for transmitting information about external stimuli * Sensory perception, the process of acquiri ...

root of a spinal nerve.

Structure

The root emerges from the

posterior Posterior may refer to: * Posterior (anatomy), the end of an organism opposite to its head ** Buttocks, as a euphemism * Posterior horn (disambiguation) * Posterior probability, the conditional probability that is assigned when the relevant evidenc ...

part of the

and travels to the

. The dorsal root ganglia contain the pseudo-unipolar

cell bodies The soma (pl. ''somata'' or ''somas''), perikaryon (pl. ''perikarya''), neurocyton, or cell body is the bulbous, non-process portion of a neuron or other brain cell type, containing the cell nucleus. The word 'soma' comes from the Greek '' σῶ� ...

of the

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the ...

fibres which travel from the ganglia through the root into the spinal cord. The

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction * Lateral cricoarytenoid muscle * Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral co ...

division of the dorsal root contains lightly

myelin Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be l ...

ated and unmyelinated fibres of small diameter. These carry pain and temperature sensation. These fibers cross through the

anterior white commissure The anterior white commissure (ventral white commissure) is a bundle of nerve fibers which cross the midline of the spinal cord just anterior (in front of) to the gray commissure (Rexed lamina X). A delta fibers (Aδ fibers) and C fibers carryi ...

to form the

anterolateral system The spinothalamic tract is a part of the anterolateral system or the ventrolateral system, a sensory pathway to the thalamus. From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory co ...

in the

lateral funiculus The most lateral of the bundles of the anterior nerve roots In anatomy and neurology, the ventral root of spinal nerve, anterior root, or motor root is the efferent motor root of a spinal nerve. At its distal end, the ventral root joins with the ...

. The

medial Medial may refer to: Mathematics * Medial magma, a mathematical identity in algebra Geometry * Medial axis, in geometry the set of all points having more than one closest point on an object's boundary * Medial graph, another graph that re ...

division of the dorsal root contains

myelinated Myelin is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be l ...

fibres of larger diameter. These transmit information of discriminative touch, pressure, vibration, and conscious

proprioception Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense". Proprioception is mediated by proprioceptors, mechanosensory neurons ...

originating from spinal levels C2 through S5. These fibers are pushed in towards the posterior median sulcus to form the

gracile fasciculus Gracility is slenderness, the condition of being gracile, which means slender. It derives from the Latin adjective ''gracilis'' ( masculine or feminine), or ''gracile'' (neuter), which in either form means slender, and when transferred for exam ...

and the

cuneate fasciculus Cuneate means "wedge-shaped", and can apply to: * Cuneate leaf, a leaf shape * Cuneate nucleus, a part of the brainstem * Cuneate fasciculus Cuneate means "wedge-shaped", and can apply to: * Cuneate leaf, a leaf shape * Cuneate nucleus, a part o ...

of the

posterior column–medial lemniscus pathway Posterior may refer to: * Posterior (anatomy), the end of an organism opposite to its head ** Buttocks, as a euphemism * Posterior horn (disambiguation) * Posterior probability, the conditional probability that is assigned when the relevant evi ...

. If the dorsal root of a spinal nerve were severed it would lead to numbness in certain areas of the body.

Additional images

File:Cervical vertebra english.png, Cervical vertebra File:Medulla spinalis - Section - English.svg, Medulla spinalis File:Gray675.png, A spinal nerve with its anterior and posterior roots. File:Gray759.png, The sensory tract. File:Gray770-en.svg, Diagrammatic transverse section of the medulla spinalis and its membranes. File:Gray796.png, A portion of the spinal cord, showing its right lateral surface. The dura is opened and arranged to show the nerve roots. File:Gray799.svg, Scheme showing structure of a typical spinal nerve.

References

External links

* - "Superior view of a section through the spinal cord within the

vertebral foramen In a typical vertebra, the vertebral foramen is the foramen (opening) formed by the anterior segment (the body), and the posterior part, the vertebral arch. The vertebral foramen begins at cervical vertebra #1 (C1 or atlas) and continues infer ...

." * - "Spinal Root Nerve Fibers"
Dorsal Root - Cell Centered Database
{{Authority control Back anatomy Peripheral nervous system

Structure

Additional images

See also

References

External links