A 17-month-old boy died after suffering a catalogue of injuries including a broken back which would have left him paralysed, the Old Bailey has heard.
The child had eight fractured ribs, a missing tooth and the tops of his fingers were also missing.
The baby's mother and her boyfriend, who cannot be named, and Jason Owen, 36, of Bromley, south-east London, deny murdering the child.
The court was told the baby died in August 2007, in Haringey, north London.
'Brutal and sadistic'
A 15-year-old runaway staying at the house had later claimed to police that the mother's boyfriend had carried out "brutal and sadistic" assaults on the child, jurors heard.
"She told them he would shake him, punch him, swing him around by his legs and spin him round on the computer chair until he fell off," said Sally O'Neill, QC, for the prosecution.
"He would wrap him up and leave him sweating until he was dehydrated."
Over the last seven or eight months of his short life, the baby was subjected to a course of assaults of increasing violence, Miss O'Neill told the court.
She added: "The Crown's case against these defendants is that either they themselves inflicted this unlawful force on him or that they participated in a joint enterprise to do so."
The eight fractured ribs were more than a week old, the lesions on his scalp and ears were ulcerated and there was a healing tear to the membrane between his lip and gum, she said.
The most serious injury had been the broken back.
Ms O'Neill said: "That particular injury requires an extremely forceful hyperextension of the spine by, for example, forcing a child's back over your bent knee or over a banister rail.
"The effect of that particular assault would have been to cause paralysis from the level of injury down."
Ms O'Neill added that the death of a child in such circumstances was "likely to fill any reasonable person with revulsion".
She said the mother and her boyfriend began a relationship in June 2006 when the baby was three months old.
After his birth she had been diagnosed with depression and, because of previous post-natal depression, the family had been placed in the "cause for concern" category by a health visitor, but they were removed shortly afterwards.
The court heard the child was taken to see doctors a number of times for numerous injuries and the family was referred to social services in December by a consultant who treated the child for bruising.
On 19 December, the mother and her partner were arrested for assaulting the baby, and bailed.
The baby's name was placed on the Haringey Child Protection Register under the categories of neglect and physical abuse, the court heard, and the boy was then placed with a friend.
Tests on the baby's injuries proved inconclusive and he was returned to the mother, although the police investigation continued and there were regular visits from social workers, Ms O'Neill said.
The case continues.