Kemarni Watson Darby was unresponsive on June 5, 2018 when paramedics arrived at the flat in West Bromwich where he lived.
His mother Alicia Watson, 31, and her alleged ex-partner Nathaniel Pope, 30, of Wolverhampton, are on trial accused of murder and subjecting him to painful beatings in the months prior to his death.
Consultant paediatrician Dr Jodie Lestner told the court that Kermarni was given cardiopulmonary resuscitation (CPR) for 63 minutes in hospital, in addition to treatment given by West Midlands Ambulance Service.
Under cross-examination by Mr Jonas Hankin, defending Pope, she also said: "I did note that there were a number of bruises on Kemarni's chest and abdomen which were of concern, but which could have been caused by CPR."
She apologised to the court that that no examination note was made of the appearance of skin on the roof of the child's mouth and added that it was routine to carry out such checks.
Dr Lestner told the jury: "A common sign of injury caused intentionally is that the skin is ripped or torn and there was no evidence of that in my recollection.
"But I have not noted that specific finding."
The jury previously heard that Kemarni suffered multiple fractures to his rib cage, internal cuts and bruising, that his death was caused by massive internal bleeding.
Pope, 31, of Evans Street, in Whitmore Reans, Wolverhampton, and Watson, 30, of Raglan Road, Handsworth, both deny murder and child cruelty.
The trial continues at Birmingham Crown Court.