Betz cells (also known as pyramidal cells of Betz) are giant
pyramidal cells
Pyramidal cells, or pyramidal neurons, are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cor ...
(
neurons
A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...
) located within the fifth layer of the
grey matter
Grey 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 distingui ...
in the
primary motor cortex
The primary motor cortex (Brodmann area 4) is a brain region that in humans is located in the dorsal portion of the frontal lobe. It is the primary region of the motor system and works in association with other motor areas including premotor co ...
. These neurons are the largest in the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...
, sometimes reaching 100
μm in diameter.
[Nolte, J. ''The Human Brain'', 5th ed. Mosby: Missouri; 2002, p.527. ]
Betz cells are
upper motor neuron
Upper 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 t ...
s that send their
axon
An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action po ...
s down to the
spinal cord
The 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 spi ...
via the
corticospinal
The pyramidal tracts include both the corticobulbar tract and the corticospinal tract. These are aggregations of efferent nerve fibers from the upper motor neurons that travel from the cerebral cortex and terminate either in the brainstem (''co ...
tract, where in
human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
s they
synapse
In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell.
Synapses are essential to the transmission of nervous impulses from ...
directly with
anterior horn cells
Cell most often refers to:
* Cell (biology), the functional basic unit of life
Cell may also refer to:
Locations
* Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery w ...
, which in turn synapse directly with their target
muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...
s. Betz cells are not the sole source of direct connections to those neurons because most of the direct corticomotorneuronal cells are medium or small neurons.
While Betz cells have one
apical dendrite An apical dendrite is a dendrite that emerges from the apex of a pyramidal cell. Apical dendrites are one of two primary categories of dendrites, and they distinguish the pyramidal cells from spiny stellate cells in the cortices. Pyramidal cells a ...
typical of pyramidal neurons, they have more primary dendritic shafts, which can branch out at almost any point from the
soma
Soma may refer to:
Businesses and brands
* SOMA (architects), a New York–based firm of architects
* Soma (company), a company that designs eco-friendly water filtration systems
* SOMA Fabrications, a builder of bicycle frames and other bicycle ...
(cell body).
These perisomatic (around the cell body) and
basal dendrite
A basal dendrite is a dendrite that emerges from the base of a pyramidal cell that receives information from nearby neurons and passes it to the soma, or cell body. Due to their direct attachment to the cell body itself, basal dendrites are able t ...
s project into all cortical layers, but most of their horizontal branches/arbors populate layers V and VI, some reaching down into the
white matter
White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distribution ...
.
According to one study, Betz cells represent about 10% of the total pyramidal cell population in layer Vb of the human primary motor cortex.
Betz cells are named after Ukrainian scientist
Volodymyr Betz, who described them in his work published in 1874.
[Betz W. (1874) ''Anatomischer Nachweis zweier Gehirncentra.'' Centralblatt für die medizinischen Wissenschaften. 12:578-580, 595-599.]
Notes
External links
*
NIF Search - Betz Cellvia the
Neuroscience Information Framework
The Neuroscience Information Framework is a repository of global neuroscience web resources, including experimental, clinical, and translational neuroscience databases, knowledge bases, atlases, and genetic/ genomic resources and provides many aut ...
{{Cortex types
Cerebral cortex
Human cells
Motor system