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 that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

. 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 do ...

. Nerve fibres with the

ventral root Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

then combine to form a

spinal nerve A spinal nerve is a mixed nerve, which carries Motor neuron, motor, Sensory neuron, sensory, and Autonomic nervous system, autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each s ...

. The dorsal root transmits sensory information, forming the afferent sensory root of a spinal nerve.

Structure

The root emerges from the posterior part of the

and travels to the

. The dorsal root ganglia contain the pseudo-unipolar cell bodies of the

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the Electrochemistry, electrochemical nerv ...

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

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

division of the dorsal root contains lightly

myelin Myelin Sheath ( ) is a lipid-rich material that in most vertebrates surrounds the axons of neurons to insulate them and increase the rate at which electrical impulses (called action potentials) pass along the axon. The myelinated axon can be lik ...

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 carr ...

to form the

anterolateral system The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

in the

lateral funiculus The most lateral of the bundles of the anterior nerve roots is generally taken as a dividing line that separates the anterolateral system into two parts. These are the anterior funiculus, between the anterior median fissure and the most lateral ...

. The medial division of the dorsal root contains myelinated fibres of larger diameter. These transmit information of discriminative touch, pressure, vibration, and conscious

proprioception Proprioception ( ) is the sense of self-movement, force, and body position. Proprioception is mediated by proprioceptors, a type of sensory receptor, located within muscles, tendons, and joints. Most animals possess multiple subtypes of propri ...

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 examp ...

and the cuneate fasciculus of the

posterior column–medial lemniscus pathway Posterior may refer to: * Posterior (anatomy), the end of an organism opposite to anterior ** Buttocks, as a euphemism * Posterior horn (disambiguation) * Posterior probability The posterior probability is a type of conditional probability that ...

. 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 In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In sauropsid s ...

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) of a vertebra bounded ventrally/anteriorly by the body of the vertebra, and the dorsally/posteriorly by the vertebral arch. In the articulated spine, the successive vertebral ...

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

Structure

Additional images

See also

References

External links