Neurological Glossary

Macrocephaly

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

Macula

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

Massage

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.

Medial

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

Medulla

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

Medulloblastoma

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

Megalencephaly

Abnormally large

Meissner corpuscles

Dermal mechanoreceptors that subserve light touch sensation

MELAS (Mitochondrial Encephalomyopathy

Lactic Acidosis

Memory

Memory is the ability to take in

Meningeal carcinomatosis

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

Meninges

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

Meningioma

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

Meningitis

Inflammation of meninges and spinal fluid

Meningocele

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

Meninx

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

Mesencephalon

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

Microcephaly

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

Microglia

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

Micrographia

Small

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

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

Miosis

Pupillary constriction

Mitochondrial myopathies

Neuromuscular diseases caused by damage to the mitochondria (small

MLD

Moderate Learning Difficulties

Mollaret meningitis

Benign recurrent aseptic meningitis

Monoplegia

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

Motor

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

Mutism

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

Mydriasis

Pupillary dilation

Myelencephalon

see medulla

Myelin

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

Myelitis

Inflammatory disease of the spinal cord

Myelogram

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

Myelomeningocele

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

Myelopathy

Symptoms and signs associated with spinal cord compression

Myocardial infarction

The medical term for a heart attack

Myoclonus

Sudden

Myokymia

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

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

Myotonia

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