A lot of functions prefixed with SV_ comprise this file. Especially interesting are the following functions:
SV_RunThink calles the think function of the entity if necesseray. We get here by:
G_RunFrame, G_RunEntity, SV_Physics_....., SV_RunThink
SV_Impact calls entities Touch functions. We get here through: G_RunEntity, (SV_Physics_Toss, SV_PushEntity or SV_Physics_Step, SV_FlyMove), SV_Impact