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Betz cells (also known as pyramidal cells of Betz) are giant pyramidal cells located within the fifth layer of the grey matter in the primary motor cortex.These neurons are the largest in the central nervous system, sometimes reaching 100 μm in diameter.
A motor neuron (or motoneuron or efferent neuron [1]) 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. [2]
Date/Time Thumbnail Dimensions User Comment; current: 03:57, 22 July 2010: 410 × 485 (99 KB): Andrew c: changes per graphic lab discussion en.wiki : 17:25, 14 July 2010
In that view, a neuron in the motor cortex sends an axon or projection to the spinal cord and forms a synapse on a motor neuron. The motor neuron sends an electrical impulse to a muscle. When the neuron in the cortex becomes active, it causes a muscle contraction. The greater the activity in the motor cortex, the stronger the muscle force.
While their cell bodies are found in the central nervous system (CNS), α motor neurons are also considered part of the somatic nervous system—a branch of the peripheral nervous system (PNS)—because their axons extend into the periphery to innervate skeletal muscles. An alpha motor neuron and the muscle fibers it innervates comprise a motor ...
Confocal microscope image of cerebellar Purkinje cells expressing tdTomato. These cells are some of the largest neurons in the human brain (Betz cells being the largest), [5] with an intricately elaborate dendritic arbor, characterized by a large number of dendritic spines. Purkinje cells are found within the Purkinje layer in the cerebellum.
The PNS includes motor neurons, mediating voluntary movement; the autonomic nervous system, comprising the sympathetic nervous system and the parasympathetic nervous system and regulating involuntary functions; and the enteric nervous system, a semi-independent part of the nervous system whose function is to control the gastrointestinal system.