A doctor at the Royal Children's Hospital said Michelle Claire Green probably grasped her daughter's nails with tweezers or something similar to forcibly remove them.
Dr John Harry told Melbourne Magistrates' Court that Green, 49, may not have had enough purchase to remove the baby's nails using her fingers.
Green, who the court heard was intellectually disabled, and her mother took the little girl to Frankston Hospital on April 7, 2006, where staff noticed injuries to her hands, arm and head.
Dr Harry told defence barrister Richard Backwell that the baby did not need hospitalisation and he thought her nails would grow back as there was no damage to the nail beds.
Social worker Shelley Mullens said in evidence that Green, whose baby has since been moved to foster care, told her in an interview it had been easy to remove the nails because "there was no resistance".
Ms Mullens denied Mr Backwell's suggestion she kept asking Green questions "until she gave you the answers you wanted".
Re-examined by prosecutor Russell Hammill, Ms Mullens said she would not have persisted with the interview if Green had not understood anything.
It was alleged that Green's response when it was put to her that the baby's nails had been forcibly pulled out was: "I don't know. I didn't want to tell you. You might take her off me."
Magistrate Charlie Rozencwajg found there was enough evidence for a jury to convict Green.
She then reserved her plea on four charges that included intentionally and recklessly causing serious injury.
Green, of Cranbourne, was bailed to appear for a case conference in the County Court in April.