Neurological Glossary

Neurological terms are often complicated and difficult to understand. The following glossary defines a variety of terms to help you understand neurological terminology:

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Head circumference that is more than 2 standard deviations above the mean for age


    Part of the retina responsible for detailed central vision

      Magnetic Resonance Angiography (MRA)

      Process that involves injection of contrast material into a blood vessel and uses a large

        Magnetic Resonance Imaging (MRI)

        A type of scan that uses a large powerful magnet to create an image of part of the body. Provides detailed structural information on the brain

          Mammillary bodies

          Pair of nuclei in the posterior


            Manipulation of the soft tissues of the body with the hands or using an electric massage appliance. Can aid relaxation

              Mass effect

              Structural damage due to a lesion's bulk (e.g.


                Nearer the midline

                  Median Plane

                  Vertical plane passing through the centre of the body dividing it into a right and left half

                    Medial geniculate nucleus

                    Nucleus of the posterior

                      Medial lemniscus

                      Ascending axonal tract in the brainstem that carries tactile and proprioceptive information from the dorsal column nuclei to the ventral posterior lateral nucleus of the thalamus

                        Medial longitudinal fasciculus

                        Pathway connecting the ipsilateral 3rd nerve nucleus in the midbrain to the contralateral 6th nerve nucleus in the pons for ocular motor control

                          Medication overuse headache (analgesic rebound headache)

                          Headache disorder characterized by headache that is present on 15 or more days per month in association with the use of any analgesic (including aspirin


                            A part of the brainstem that helps regulate respiration and other behaviours


                              Aggressive tumour in children and young adults typically involving the posterior fossa sometimes with cerebrospinal fluid seeding (drop metastases); characterized histologically by small blue cells and Homer Wright rosettes

                                Medulla oblongata (myelencephalon)

                                Caudal aspect of the brainstem located between the Pons and the spinal cord


                                  Abnormally large

                                    Meissner corpuscles

                                    Dermal mechanoreceptors that subserve light touch sensation

                                      MELAS (Mitochondrial Encephalomyopathy

                                      Lactic Acidosis


                                        Memory is the ability to take in

                                          Meningeal carcinomatosis

                                          Diffuse infiltration of the meninges by metastatic tumour cells often with positive cerebrospinal fluid cytology


                                            Three distinct connective tissue membranes (from outer to inner: dura


                                              Slow-growing WHO grade I meningeal neoplasm that has an extra-axial location and often shows a dural tail sign and hyperostosis of adjacent skull; characterized histologically by whorls and psammoma bodies


                                                Inflammation of meninges and spinal fluid


                                                  Form of spina bifida in which there is herniation of only meninges (no spinal cord parenchyma) through defective posterior arches


                                                    Singular form of meninges

                                                      Menstrual (catamenial) migraine

                                                      Migraine occurring between one day before and four days after the onset of menses; thought to be due to estrogen withdrawal

                                                        Merkel cells

                                                        Disk-shaped receptor endings in the skin believed to be involved with the sensation of fine touch


                                                          see midbrain

                                                            Mesial temporal sclerosis

                                                            Hippocampal scarring and volume loss; most common cause of temporal lobe epilepsy

                                                              Mesulam syndrome

                                                              Eponym for primary progressive aphasia

                                                                Metachromatic leukodystrophy

                                                                Autosomal recessive disease associated with large confluent areas of discoloured gelatinous white matter caused by deficiency of the enzyme arylsulfatase A

                                                                  Meyer's loop

                                                                  Part of the optic radiations that fans out into the temporal lobe and carries information from the upper visual world


                                                                    Head circumference that is smaller than normal because the brain has not developed properly or has stopped growing; most often caused by genetic abnormalities


                                                                      Bone marrow derived phagocytic cells that are involved in immune reactions in the CNS microglial nodules formation of clusters of activated microglia around foci of necrotic brain tissue



                                                                          MID (Multi-Infarct Dementia)

                                                                          Multi-infarct dementia is a form of dementia caused by a number of small blood clots (emboli) in the brain that starve the brain cells of oxygen. Also known as Vascular Dementia.

                                                                            Midbrain (mesencephalon)

                                                                            Rostral aspect of the brainstem located between the pons and the diencephalon

                                                                              Middle cerebellar peduncle (brachium pontis)

                                                                              Paired bundle of fibres originating from the pontine nuclei

                                                                                Middle cerebral artery

                                                                                The artery that most frequently becomes blocked and causes stroke

                                                                                  Middle cranial fossa

                                                                                  Butterfly-shaped portion of the internal base of the skull housing the temporal lobes laterally and the pituitary centrally


                                                                                    Migraine is a severe form of a headache

                                                                                      Mild cognitive impairment (MCI)

                                                                                      Cognitive changes intermediate between normal aging and clinically diagnosed Alzheimer disease; identifies individuals believed to be at risk for Alzheimer disease

                                                                                        Millard-Gubler syndrome

                                                                                        Ipsilateral lateral rectus palsy


                                                                                          Pupillary constriction

                                                                                            Mitochondrial myopathies

                                                                                            Neuromuscular diseases caused by damage to the mitochondria (small


                                                                                              Moderate Learning Difficulties

                                                                                                Mollaret meningitis

                                                                                                Benign recurrent aseptic meningitis


                                                                                                  Paresis or paralysis affecting one limb only

                                                                                                    Mononeuropathy multiplex (mononeuritis multiplex)

                                                                                                    Condition associated with various systemic disorders (e.g.

                                                                                                      Monroe-Kellie doctrine

                                                                                                      Doctrine stating that an increase in the volume of any of its three components (brain

                                                                                                        Moro reflex

                                                                                                        Normal neonatal reflex consisting of symmetric abduction followed by adduction of both arms


                                                                                                          Relating to movement

                                                                                                            Motor neglect

                                                                                                            Inability to look or reach toward left-sided objects

                                                                                                              Motor neurons

                                                                                                              Nerve cells that direct movement

                                                                                                                Motor neuron disease

                                                                                                                Dysfunction of alpha motor neurons; motor neuronopathy

                                                                                                                  Motor unit

                                                                                                                  Motor neuron axon and the individual muscle fibres it branches to contact

                                                                                                                    Moyamoya disease

                                                                                                                    Is a rare

                                                                                                                      Muller's muscle

                                                                                                                      Eyelid muscle innervated by the sympathetic nervous system that functions to elevate the upper eyelid; interruption of these sympathetic fibres results in the ptosis that is part of Horner's syndrome.

                                                                                                                        Multi-infarct dementia

                                                                                                                        Form of vascular dementia involving deterioration of mental function caused by infarcts in multiple brain regions

                                                                                                                          Multiple sclerosis

                                                                                                                          Inflammatory demyelinising disease with relative axonal sparing of the central nervous system usually characterized by recurrent attacks of focal and multifocal neurological disability

                                                                                                                            Multisystems atrophy (MSA)

                                                                                                                            A degenerative neurological disorder associated with the degeneration of nerve cells in specific areas of the brain. This cell degeneration causes problems with movement

                                                                                                                              Muscle spindle

                                                                                                                              Stretch receptor in vertebrate muscle that is innervated by both sensory and motor neurons axons and sends proprioceptive information about the muscle to the central nervous system

                                                                                                                                Muscle stretch reflex

                                                                                                                                Two-neuron reflex in which a sensory neurons senses muscle extension and provides direct excitatory feedback to a motor neurons innervating the same muscle

                                                                                                                                  Muscle tone

                                                                                                                                  The degree of tension in a muscle when at rest


                                                                                                                                    Inability to produce any verbal utterance; may be due to disordered language

                                                                                                                                      Myasthenia gravis

                                                                                                                                      Myasthenia gravis or grave muscle weakness is an autoimmune neuromuscular condition affecting the muscles in the body causing varying degrees of weakness. Myasthenia gravis is caused by the body's immune system attacking the nerves supplying the muscles.

                                                                                                                                        Mycotic aneurysm

                                                                                                                                        Infective aneurysm typically developing distal to the Circle of Willis and reflecting local bacterial or fungal intramural growth with rupture of the vascular wall


                                                                                                                                          Pupillary dilation


                                                                                                                                            see medulla


                                                                                                                                              Fatty substance forming an insulating sheath around axons to increase the velocity of action potential conduction


                                                                                                                                                Inflammatory disease of the spinal cord


                                                                                                                                                  Diagnostic procedure in which contrast material is injected into the spinal subarachnoid space allowing visualization of the spinal cord and nerve roots


                                                                                                                                                    Form of spina bifida in which there is herniation of meninges and spinal cord parenchyma through defective posterior arches


                                                                                                                                                      Symptoms and signs associated with spinal cord compression

                                                                                                                                                        Myocardial infarction

                                                                                                                                                        The medical term for a heart attack




                                                                                                                                                            Involuntary repetitive contractions of muscle fibres lasting a few seconds and giving a continuous rippling or undulating appearance to the overlying skin; associated with nerve irritation


                                                                                                                                                              Myopathy or 'muscle disease' is a neuromuscular disorder caused by damage to muscle fibres which results in muscle weakness and impaired function


                                                                                                                                                                Muscle disorder characterized by abnormally prolonged contraction (delayed relaxation of the muscle after a forceful contraction)