| Dorsal column nuclei | |
|---|---|
| Identifiers | |
| NeuroLex ID | nlx_153860 |
| Anatomical terms of neuroanatomy | |
| Dorsal column nuclei | |
|---|---|
 Present at the junction between thespinal cord andmedulla oblongata, the dorsal column nuclei consist of paired gracile, and cuneate nuclei (labels 6 and 7, respectively). | |
| Details | |
| System | Somatosensory system |
| Identifiers | |
| NeuroLex ID | nlx_153860 |
| Anatomical terminology | |
Thedorsal column nuclei are a pair ofnuclei in the dorsal columns of thedorsal column–medial lemniscus pathway (DCML) in thebrainstem.[1] The name refers collectively to thecuneate nucleus andgracile nucleus, which are situated at the lower end of themedulla oblongata. Both nuclei containsecond-order neurons of the DCML, which conveyfine touch andproprioceptive information from the body to thebrain via thethalamus.
The dorsal column nuclei each have an associatednerve tract in thespinal cord, thegracile fasciculus and thecuneate fasciculus, together forming thedorsal columns. Both dorsal column nuclei contain synapses fromafferent nerve fibers that have travelled in the spinal cord.[2] They then send on second-orderneurons of thedorsal column–medial lemniscal pathway.
Neurons of the dorsal column nuclei eventually reach themidbrain and thethalamus.[3] They sendaxons that form theinternal arcuate fibers.[4] These cross over at thesensory decussation to form themedial lemniscus.[4] They thensynapse with third-order neurons of the thalamus.[4]
The major nuclei are the cuneate nucleus and gracile nucleus.[5] These are present at the bottom of themedulla oblongata.[6]
Thegracile nucleus is medial to the cuneate nucleus.[5] Its neurons receive afferent input fromdorsal root gangliasensory neurons of the lowertorso and thelower limbs.[5] The gracile nucleus andgracile fasciculus carryepicritic,kinesthetic, and consciousproprioceptive information from the lower part of the body (below the level of T6 in the spinal cord). Because of the large population of neurons in the gracile nucleus they give rise to a raised area called thegracile tubercle on the posterior side of the closed medulla at the floor of thefourth ventricle.
Thecuneate nucleus is lateral to the gracile nucleus.[5] It carries the same type of information, but from the upper body and theupper limbs (except theface, which is carried by theprincipal sensory nucleus of trigeminal nerve).[5] The cuneate nucleus is wedge-shaped and located in the closed part of the medulla. It lies lateral to the gracile nucleus and medial to the spinal trigeminal nucleus in the medulla. The large number of neurons found there give rise to thecuneate tubercle seen on viewing the posterior aspect of the medulla on the side of thebrainstem.
The dorsal column nuclei help to carryfine touch andproprioceptive information from the body to thebrain. The gracile nucleus carries information from the lowertorso and thelower limbs.[5] The cuneate nucleus carries information from the upper body and theupper limbs.[5]
The dorsal column nuclei may degenerate duringageing, although evidence for this is not conclusive.[7] This may reduce the sensitivity oftouch andproprioception.[7]
In some other animals, a third nucleus is present, known as the median accessory nucleus.[5] This may carry information from thetail.[5]
