The optic chiasm or optic chiasma (Greek χίασμα, "crossing", from the Greek χιαζω 'to mark with an X', after the Greek letter 'Χ', chi) is the part of the brain where the optic nerves (CN II) partially cross. The optic chiasm is located at the bottom of the brain immediately below the hypothalamus.
Alternating hemiplegia refers to a form of hemiplegia that has an ipsilateral and contralateral presentation in different parts of the body. This type of syndrome can result from a unilateral lesion in the brainstem affecting both upper motor neurons and lower motor neurons. The muscles that would receive signals from these damaged upper motor neurons result in spastic paralysis.
Neurolemma (also known as neurilemma or sheath of Schwann) is the outermost nucleated cytoplasmic layer of Schwann cells that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system. The neurolemma is underlain by the basal lamina (referred to as the medullary sheath in the included illustrations. In CNS, axons are myelinated by oligodendrocytes, thus lack neurolemma. A neurilemoma is a tumor of the neurilemma.
The splanchnic nerves are paired nerves that contribute to the innervation of the viscera, carrying fibers of the autonomic nervous system as well as sensory fibers from the organs. All carry sympathetic fibers except for the pelvic splanchnic nerves, which carry parasympathetic fibers.
Micropsia is a neurological condition affecting human visual perception in which objects are perceived to be smaller than they actually are. Micropsia can be caused by either optical distortion of images in the eye (as by glasses or certain ocular conditions) or by a neurological dysfunction. The condition of micropsia can be caused by more factors than any other visual distortion.