Lemniscal

Lemniscal refers to anything pertaining to a lemniscus, a ribbon-like tract of axons in the brainstem. In neuroanatomy, the term is most often applied to the dorsal column–medial lemniscus system, the pathway conveying discriminative touch, vibration, and proprioception from the body to the brain. The dorsal columns carry these modalities from the periphery to the brainstem as two fasciculi: the gracile fasciculus for the lower body and the cuneate fasciculus for the upper body. They terminate in the gracile and cuneate nuclei in the medulla, where second-order neurons synapse. These second-order neurons cross to the opposite side and form the medial lemniscus, which ascends through the brainstem to reach the ventral posterior lateral nucleus (VPL) of the thalamus. Third-order neurons then project from the VPL to the primary somatosensory cortex, producing conscious perception of touch and proprioception.

The term lemniscal is sometimes used to distinguish this high-fidelity somatosensory pathway from other ascending systems such as the spinothalamic tract, which carries pain and temperature. There is also a lateral lemniscus in the auditory pathway, distinct from the dorsal column system. Clinically, lesions affecting the medial lemniscus produce contralateral loss of fine touch and proprioception from the body.