This is the larger of two spine-like processes that project from the junction of the neck and manubrium of the malleus. As its name suggests, it projects laterally to attach to the superior part of the tympanic membrane where the posterior and anterior malleolar folds form the notch of Rivinus or pars flaccida of the tympanic membrane.

Process is a term used in anatomy to describe a projection on a bone. It comes from the Latin pro- meaning forward and cessus for gone. It is an old term that can be traced back to the writings of the early anatomist Celsus.

Processus lateralis mallei