Cuneate nucleus

The cuneate nucleus (a.k.a. nucleus cuneatus), is a gray matter nucleus located in the dorsal medulla oblongata. Positioned lateral to the gracile nucleus, it marks the lower margin of the floor of the fourth ventricle. It's location is externally indicated by a tubercle or a bump on the dorsal medulla, called the cuneate tubercle.

Functionally, the cuneate nucleus is part of the dorsal column-medial lemniscus pathway, processing sensory modalities such as vibration, proprioception, and two-point discrimination. This pathway is a three-order neuron system. Originating from the ipsilateral or same side of the body above the T6 level, first-order neurons transmit this sensory information via the cuneate fasciculus to synapse in the cuneate nucleus.

Next, the second-order neurons arising from the cuneate nucleus project as internal arcuate fibers, crossing (decussating) to form the medial lemniscus. These fibers subsequently ascend to the Ventral Posterolateral (VPL) nucleus of the thalamus for further processing.

Lesions affecting the cuneate nucleus or its fasciculus can result in sensory deficits, particularly affecting the arms and upper trunk, indicative of damage above the T6 level.