Madison Ricketts-Devereux, 22, and her partner Craig Sayers, 32, have been jailed for inflicting horrific injuries on the defenceless 15-month-old tot in January 2017.
A court heard the duo left the youngster with a broken arm, two fractured fingers and pulled her nail during the abuse at their home in Ledbury, Hertfordshire.
Their sickening crimes only came to light when Ricketts-Devereux took the girl hospital and doctors realised she was unable to raise her arm.
Medics then discovered a catalogue of injuries over the child’s body, including evidence one of her toenails had been pulled out.
On Wednesday, Ricketts-Devereux and Sayers were both found guilty of causing grievous bodily harm following a trial at Hereford Crown Court.
Sayers, of Worcester, was jailed for nine years while Ricketts-Devereux, of Ledbury, was caged for six years.
Jailing the couple, Recorder Martin Jackson said: “Madison Ricketts-Devereux, you were the only person with the opportunity to cause the damage to the right arm.
“Craig Sayers you went into the room and caused injuries to the left arm and toe. This was a vulnerable victim and there was an element of sustained assault.
“There are aggravating features as you were on bail at the time for another case of violence. You had breached trust as you had been trusted to settle the child.
“The nature of the injuries is also an aggravating factor, as was the fact that the injuries were caused at her home.
“I do not think that your previous good character is a mitigating factor. You were old enough to know better.
“Madison Ricketts-Devereaux, your immaturity is a mitigating factor, however, you still caused injuries to your child.”
Christopher Millington, defending, said Sayers gone through his early life without offending and had been a man of “good character” until he was 31-years-old.
He added: “The shame of this conviction weighs heavily on him.”
Mum-of-two, Ricketts-Devereux, was described as “immature, damaged and vulnerable.”
Mr Millington said: “She suffered some very serious experiences in her childhood and this brought about some very disturbed behaviour as a young teen.
“This baby had not suffered any injuries before her relationship with Craig Sayers. What impact did their relationship have upon the mother?”