Betz cells

Betz cells are also known as pyramidal cells of Betz.  

They are giant pyramidal neuronal 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.

Betz cells are upper motor neurons that send their axons down to the spinal cord via the corticospinal tract.

Betz cell axons synapse directly with anterior horn cells, which in turn synapse directly with their target muscles. 

Betz cells are not the sole source of direct connections to motor neurons because most of the direct corticomotorneuronal cells are medium or small neurons.

Betz cells have one apical dendrite typical of pyramidal neurons, they also have more primary dendritic shafts, which can branch out at almost any point from the cell body.

These perisomatic and basal dendrites project into all cortical layers.

According to one study, Betz cells represent about 10% of the total pyramidal cell population in the  primary motor cortex.

In the primary motor cortex of the frontal lobe, layer V contains giant pyramidal cells called Betz cells, whose axons travel through the internal capsule, the brain stem, and the spinal cord forming the corticospinal tract, which is the main pathway for voluntary motor control.

Betz cells have a rapid conduction rate, over 70m/sec, the fastest conduction of any signals from the brain to the spinal cord.

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