Upper motor neuronUpper motor neurons (UMNs) is a term introduced by William Gowers in 1886. They are found in the cerebral cortex and brainstem and carry information down to activate interneurons and lower motor neurons, which in turn directly signal muscles to contract or relax. UMNs in the cerebral cortex are the main source of voluntary movement. They are the larger pyramidal cells in the cerebral cortex. There is a type of giant pyramidal cell called Betz cells and are found just below the surface of the cerebral cortex within layer V of the primary motor cortex.
Spinal cordThe spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae.
Post-polio syndromePost-polio syndrome (PPS, poliomyelitis sequelae) is a group of latent symptoms of poliomyelitis (polio), occurring at about a 25–40% rate (latest data greater than 80%). These symptoms are caused by the damaging effects of the viral infection on the nervous system. Symptoms typically occur 15 to 30 years after an initial acute paralytic attack. Symptoms include decreasing muscular function or acute weakness with pain and fatigue. The same symptoms may also occur years after a nonparalytic polio (NPP) infection.
ALSAmyotrophic lateral sclerosis (ALS), also known as motor neurone disease (MND) or Lou Gehrig's disease, is a rare neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most common form of the motor neuron diseases. Early symptoms of ALS include stiff muscles, muscle twitches, gradual increasing weakness, and muscle wasting. Limb-onset ALS begins with weakness in the arms or legs, while bulbar-onset ALS begins with difficulty in speaking or swallowing.
Vertebral columnThe vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordates has been replaced by a segmented series of bone: vertebrae separated by intervertebral discs. Individual vertebrae are named according to their region and position, and can be used as anatomical landmarks in order to guide procedures such as lumbar punctures.
Spinal muscular atrophySpinal muscular atrophy (SMA) is a rare neuromuscular disorder that results in the loss of motor neurons and progressive muscle wasting. It is usually diagnosed in infancy or early childhood and if left untreated it is the most common genetic cause of infant death. It may also appear later in life and then have a milder course of the disease. The common feature is progressive weakness of voluntary muscles, with arm, leg and respiratory muscles being affected first.
Grey matterGrey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. Grey matter is distinguished from white matter in that it contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively few cell bodies and is composed chiefly of long-range myelinated axons. The colour difference arises mainly from the whiteness of myelin.
Somatic nervous systemThe somatic nervous system (SNS), or voluntary nervous system is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles. The somatic nervous system consists of nerves carrying afferent nerve fibers, which relay sensation from the body to the central nervous system (CNS), and nerves carrying efferent nerve fibers, which relay motor commands from the CNS to stimulate muscle contraction. The a- of afferent and the e- of efferent correspond to the prefixes ad- (to, toward) and ex- (out of).
Motor neuronA motor neuron (or motoneuron or efferent neuron) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly muscles and glands. There are two types of motor neuron – upper motor neurons and lower motor neurons. Axons from upper motor neurons synapse onto interneurons in the spinal cord and occasionally directly onto lower motor neurons.
BrainstemThe brainstem (or brain stem) is the stalk-like part of the brain that interconnects the cerebrum and diencephalon with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch. The brainstem is very small, making up around only 2.6 percent of the brain's total weight. It has the critical roles of regulating cardiac, and respiratory function, helping to control heart rate and breathing rate.
