A motorized joint unit of a mechanism comprises a rotor assembly and a stator assembly operatively assembled and configured for being secured to respective links of the mechanism. The rotor assembly and the stator assembly respectively include a rotor and a stator concurrently operable to cause a rotation of a rotor of the rotor assembly relative to a stator of the stator assembly about a rotational axis, a receiving volume delimited by one of the rotor assembly and stator assembly, the rotational axis passing through the receiving volume. A brake assembly is located at least partially in the receiving volume and comprising a brake plunger having a brake surface for brakingly engaging with a corresponding surface of the rotor assembly, the brake plunger displaceable in translation in the brake assembly, and a solenoid coil actuatable to displace the brake plunger against the rotor assembly.