Injection device

An injection device for injecting medicament in a patient comprising:

• a housing having at least one retaining arm and at least one retaining rib;
• a syringe coupled to the housing and radially retained relative to the housing by the at least one retaining rib, the syringe having a needle and a piston;
• a needle guard slideably coupled to the housing and spring biased in a distal direction relative to the housing by a return spring;
• a ram slideably coupled to the housing and spring biased in the distal direction relative to the housing by a main spring, the ram having a rod coupled to the piston, the ram having at least one lock arm;
• an initial position defined by the at least one retaining arm being disposed in the longitudinal path of the ram preventing firing of the ram;
• a released position defined by the at least one retaining arm being clear from the longitudinal path of the ram allowing the ram to extend distally relative to the housing;
• and
• a locked position defined by the at least one retaining arm being disposed in the longitudinal path of the ram and the at least one lock arm being disposed in the longitudinal path of the needle guard preventing the needle guard from being retracted relative to the housing,
• wherein the housing includes at least one hook configured to abut against a portion of the needle guard in the released position and radially flex the at least one lock arm as the lock arm extends distally.