The internal arcuate fibers decussate and continue ascending as the contralateral medial lemniscus. The medial lemniscus is formed by the crossings of the internal arcuate fibers. The posterior external arcuate fibers carry proprioceptive information from the upper limbs and neck. Nuclei of cranial nerves, arcuate nuclei, and posterior horn cells were also affected. A rack gear that is curved is called an arcuate rack. The family is distinguished by the arcuate (strongly curved) basal vein found on the wing. The internal arcuate fibers are composed of axons of nucleus gracilis and nucleus cuneatus. It possesses small maxillary barbels and an unfringed shallowly arcuate upper lip. These two regions are interconnected by a large white matter tract, the arcuate fasciculus. The arcuate nucleus contains two distinct groups of neurons. Neurons of the arcuate nucleus have intrahypothalamic projections for neuroendrocrine circuitry. Leptin acts on cell receptors in the arcuate nucleus of the hypothalamus. This anatomical variant is known as an arcuate foramen. The arcuate foramen is a common anatomical variation more frequently seen in females. Both groups of arcuate nucleus neurons are regulated in part by leptin.