| Sensory decussation | |
|---|---|
 The sensory tract | |
| Details | |
| Identifiers | |
| Latin | decussatio lemnisci medialis |
| NeuroNames | 788 |
| Anatomical terms of neuroanatomy | |
Thesensory decussation ordecussation of the lemnisci is adecussation (a crossing over) ofaxons from thegracile nucleus andcuneate nucleus, known together as thedorsal column nuclei. The dorsal column nuclei are responsible forfine touch, vibration,proprioception andtwo-point discrimination.
The fibers of this decussation are called theinternal arcuate fibers and are found at the superior aspect of the closedmedulla oblongata, superior to themotor decussation. Neurons of these nuclei aresecond-order neurons in thedorsal column–medial lemniscus pathway.
At the level of the closedmedulla in theposterior white column, two large nuclei namely the gracile nucleus and the cuneate nucleus can be found. The two nuclei receive the impulse from the two ascending tracts:fasciculus gracilis andfasciculus cuneatus. After the two tracts terminate upon these nuclei, the heavily myelinated fibres arise and ascend anteromedially around theperiaqueductal gray as internal arcuate fibres. These fibres decussate (cross) to the contralateral (opposite) side, so called the sensory decussation. The ascending bundle after the decussation is called themedial lemniscus. Unlike other ascending tracts of the brain, fibres of the medial lemniscus do not give off collateral branches as they travel along thebrainstem.[1]
The fibres that make up the sensory decussation are responsible for fine touch, proprioception and two-point discrimination of the whole body excluding the head.[1]
This article incorporates text in thepublic domain frompage 777 of the 20th edition ofGray's Anatomy(1918)
