betz cells
Betz cells are pyramidal cell neurons located within the fifth layer of the primary motor cortex. They are some of the largest in the central nervous system, sometimes reaching 100 µm in diameter and send their axons down the corticospinal tracts to the anterior horn cells of the spinal cord.
While Betz cells have one apical dendrite typical to pyramidal neurons, they have more primary dendritic shafts, and these do not leave the soma only at basal angles but rather branch out from almost any point asymmetrically. These perisomatic and basal dendrites project into all cortical layers, but most of their horizontal arbors populate layers V and VI, some reaching down into the white matter. According to one study, Betz cells represent about 10% of the total pyramidal cell population in layer Vb of the human primary motor cortex.
Related pathology
Betz cells are affected in motor neuron disease.
History and etymology
Named after Vladimir Alekseyevich Betz, Russian anatomist (1834-94).
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