Betz cell

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Betz cells are pyramidal cell neurons located within the fifth layer of the grey matter in the primary motor cortex. These neurons are some of the largest in the central nervous system, sometimes reaching 100 μm in diameter^[1]. Betz cells send their axons down to the spinal cord where in humans they synapse directly with anterior horn cells, which in turn synapse directly with their target muscles. Thus, humans are said to have monosynaptic control over voluntary movements. Descending control of muscles in most other vertebrates, including non-human primates, involves an extra synapse at spinal cord interneurons before synapsing on their target anterior horn cells.