Spinal ganglion

Spinal ganglion (a.k.a. dorsal root ganglion, pl. spinal ganglia) is a collection of nerve ‘cell bodies’ of pseudo-unipolar first order sensory neurons, that are embedded in a ‘glial’ connective tissue matrix. Each spinal ganglion is positioned along the course of a dorsal nerve root, prior to it forming the spinal nerve inside the intervertebral foramen.

Some examples of these first order sensory neurons in the spinal ganglion (or the dorsal root ganglion) include those that transmit pain, temperature, light touch and pressure sensations from free nerve endings receptors in skin and other tissues. Their axons synapse with cell bodies of second order sensory neurons (i.e. the substantia gelatinosa) in lamina II of the dorsal horn of spinal cord. The information is further conveyed to the thalamus as the lateral and the anterior spinothalamic tracts.

Other neuronal cell bodies belong to the first order sensory neurons that transmit sensory information pertaining to vibration, proprioception and 2-point discrimination. Their axons send collateral branches to the nucleus proprius neurons in lamina III and IV of the dorsal horn. Afterwards, they ascend in the dorsal column (i.e. fasciculus gracilis and fasciculus cuneatus to synapse with the nucleus gracilis and nucleus cuneatus.

Yet another example includes that of the first order sensory neurons that transmit subconscious proprioceptive information from muscle spindles and golgi tendon organs in muscle tendons, joints and ligaments. Their axons synapse with cell bodies of second order sensory neurons (i.e. Clarke’s column or dorsal nucleus of Clarke) in lamina VII of the dorsal horn of spinal cord. The information is further conveyed to the cerebellum as anterior and posterior spinocerebellar tracts.

The spinal ganglia receive their blood supply from the superficial and deep arterial plexuses from the radicular branches of segmental arteries. Spinal or dorsal root ganglion radiofrequency ablation has been employed as an important approach to treat chronic non-resolving neuropathic pain.