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Dorsal root of spinal nerve

The dorsal root is the posterior sensory component of a spinal nerve, carrying afferent sensory fibers from the peripheral receptors to the spinal cord. Each dorsal root emerges from the dorsolateral aspect of the spinal cord, extending laterally to join the ventral (motor) root and form a mixed spinal nerve.

The dorsal root contains pseudounipolar neuron axons, whose cell bodies reside in the dorsal root ganglion (DRG) located just outside the intervertebral foramen. These fibers transmit tactile, pain, temperature, and proprioceptive signals from skin, muscles, joints, and visceral structures to the central nervous system. The dorsal root is protected by surrounding meninges, fat, and the bony intervertebral foramen.

Function

  • Transmits sensory (afferent) signals from peripheral receptors to the spinal cord

  • Conveys pain, temperature, touch, pressure, and proprioception

  • Facilitates reflex arcs by providing sensory input to spinal cord circuits

  • Works in conjunction with the ventral root to form a mixed spinal nerve

  • Key structure in radiculopathy, nerve compression, and spinal injury

Synonyms

  • Posterior root of spinal nerve

  • Sensory root of spinal nerve

  • Afferent nerve root

MRI Appearance

T1-weighted images:

  • Dorsal root appears as a small, linear, low-to-intermediate signal structure extending from the dorsolateral spinal cord to the dorsal root ganglion

  • Surrounded by high signal fat in the epidural space, providing contrast

  • Pathology such as nerve compression, inflammation, or tumor may alter signal intensity

T2-weighted images:

  • Dorsal root itself is low-to-intermediate signal

  • Adjacent cerebrospinal fluid (CSF) appears hyperintense, outlining the nerve root clearly

  • Nerve root edema or inflammation may appear as hyperintense focal swelling

STIR (Short Tau Inversion Recovery):

  • Fat signal is suppressed, and dorsal root remains low signal

  • Pathological conditions such as nerve root inflammation, edema, or compression appear hyperintense, aiding early detection

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal dorsal root shows minimal or no enhancement

  • Pathological dorsal root (tumor, infection, radiculitis) demonstrates enhancement along the nerve fibers or dorsal root ganglion, highlighting abnormal vascularized tissue

CT Appearance:

  • The dorsal root itself is not directly visualized on CT, but its course is inferred within the intervertebral foramen

  • Surrounding bony structures, including the pedicles, lamina, and foramina, are clearly visualized

  • CT is useful for assessing foraminal stenosis, bony compression, or nerve root impingement

MRI images

Dorsal root of spinal nerve mri axial image -img-00000-00000

MRI images

Dorsal root of spinal nerve mri axial image

MRI images

Dorsal root of spinal nerve mri sag image

MRI image

Dorsal root of spinal nerve mri axial image