Dr Eli Newberger said nine-month-old Matthew Eappen had been subjected to a shaking so violent that it would have been carried out with as much energy as an adult could use.
It went on for up to and beyond a minute, probably in intervals, Dr Newberger told the Middlesex Superior Court in Cambridge, Massachusetts, where Miss Woodward, 19, of Elton, near Chester, is on trial for first degree murder.
Dr Newberger, a key prosecution witness, who has written seven books on child abuse and heads the Child Protection Scheme and Boston's Children's Hospital, said that from the time he first saw the baby - the day after his admission to the hospital in February - he had been in "next to no doubt" that he was a child abuse victim, who had suffered "shaken baby syndrome".
"From the clinical record and my examination it was clear this was a child whose neurological system had suffered devastating injuries."
He said they could not have been caused by a gentle shaking, the baby being tossed on a bed or being dropped on a towel covering a bathroom floor, as Miss Woodward is alleged to have told police.
Asked by prosecuting attorney Gerry Leone whether the injuries were accidental or inflicted, Dr Newberger replied: "They were inflicted."
Dr Newberger said: "This shaking was of such a violent degree that it would have required as much energy as an adult could muster, sustained over a period of time approaching or exceeding a minute, probably delivered in intervals. This child's clinical condition indicated his brain and eyes had been subjected to quite enormous direct force."
He said the injuries were at the "far end of the spectrum of severity" of about 20 cases of Shaken Baby Syndrome he saw each year. He was not surprised there were no external injuries found on the baby on his admission to hospital. "This is typical in these cases."
"My opinion is that all the injuries are attributable to child abuse," he told the court.
The doctor gave a graphic demonstration of the degree of force he said would have been necessary to cause the massive injuries. He shook his hands violently in front of him, raised them above his head and slammed them down towards the floor as he said how the baby would have been grasped firmly and shaken for a number of seconds with the greatest possible force before being slammed to the floor, causing a skull fracture to the back of his head.
The prosecution alleges that Miss Woodward killed the baby in a rage of frustration and bitterness because he was crying all day and she was unhappy with her job.
The defence claims the injury could have been caused accidentally, some days before, and that the brain injuries developed as it started to bleed again. The case continues.Reuse content