Sarah O’Brien, aged 33, of Bosworth Road, Adwick, is accused of killing her son Keigan O’Brien with her partner Martin Currie, 36, of no fixed abode.
They both deny murdering the tot, who was admitted to hospital in cardiac arrest and later died.
A post mortem examination revealed he had suffered head injuries.
Jason Pitter QC, prosecuting, told jurors at Sheffield Crown Court this week that Keigan suffered a brain bleed, possibly from having his head hit against a wall or the floor.
He said that and over the previous weeks he had suffered a broken spine, broken ribs and a broken arm.
Keigan's grandmother, Carol O’Brien, described her grandson as ‘a cuddly, lovely baby’.
Sarah O’Brien and Martin Currie, deny murder, causing cruelty to a child by ill-treatment or neglect and causing or allowing the death of a child.