I recently started reading Fitzgerald's clinical neuroanatomy and neuroscience (Mtui, et al. 2015) and reached chapter 12, electrodiagnostic examination, yesterday. The chapter deals, i.a., with nerve conduction studies and how to determine motor/sensory nerve conduction velocity (MNCV/SNCV). MNCV is about 50 m/s in a young, healthy adult as presented in the book. In a previous chapter, however, the reader is told that A$\alpha$ axons have conduction velocities ranging from 80 - 120 m/s which I also verified.
Isn't this contradictory? How can median nerve MNCV be less than the previously mentioned velocity? I know there are several fibers of a different type in the median nerve but shouldn't much rather scattering occur? What am I missing? Any help is greatly appreciated!
Mtui, E., Gruener, G., & Dockery, P. (2015). Fitzgerald's Clinical Neuroanatomy and Neuroscience. Philadelphia, PA:Elsevier.