Glossary of terms and abbreviations
CN; CNN - cranial nerves singular and plural
CNS - central nervous system
Decussation - to cross in the form of the letter ‘X’; crossing the midline (decussis - L = intersection)
Dysmetria - altered rate, range or force of movement
Epaxial - above the axis of the spinal column
Ganglia - collections of nerve cell bodies, with similar functions, located outside the CNS
Hypaxial - below the axis of the spinal column
LMN - lower motor neuron - neurons associated with motor function that have their cell body in the CNS and their axon leaves the CNS in a cranial or spinal nerve to synapse via a neuromuscular junction with striated, smooth or cardiac muscle.
They could be considered to be peripheral motor neurons.Neuraxis - brain and spinal cord
Neurocranium - the portion of the skull that houses the brain
Nuclei - collections of nerve cell bodies, with similar functions, located in the CNS
Paralysis - complete loss of strength in a limb or muscle group (paralusis - Gk = to disable, or para - Gk = beyond + lysis - Gk = loosening)
Paresis - reduction in motor function (paralyein - Greek = to be palsied)
Pathway - sequential tracts separated by synapses that are all involved in one neural function. For example, the visual pathway comprises the retinal ganglion neurons, optic nerve, optic chiasm, optic tract, a synapse in the lateral geniculate nucleus, optic radiation to the visual cortex
PNS - peripheral nervous system
Soma - Gk = body, pl = somata
Somatotopic organisation - the organisation of fibres within a tract, or region of the CNS in a precise pattern reflecting the anatomical arrangement of the body region being innervated (soma - Gk = body, topos - Gk = place)
Spinal cord segment - a section of spinal cord to which is attached a pair of dorsal and a pair of ventral nerve roots
UMN - upper motor neuron - neurons confined to the CNS that are associated with motor function. They could be considered to be central motor neurons.
Tract - a collection of nerve cells, with the same function, that originate together and terminate together and do not synapse en route. Tract names often indicate their origin and destination. For example, the spinothalamic tract travels from the spinal cord to the thalamus