A mother jailed for life for murdering her toddler son will have to wait to find out if her appeal against the conviction has been successful.

Rachel Fee, 32, argues that the judge in her 2016 trial misdirected the jury about the lesser charge of culpable homicide before sending them out to consider their verdict.

Senior judges at the Court of Criminal Appeal in Edinburgh, who heard arguments from Fee's legal team and the Crown on Friday, said they would deliver their decision in due course.

Defenceless two-year-old Liam Fee died at his home near Glenrothes, Fife, on March 22, 2014 following a prolonged campaign of horrific abuse spanning more than two years.

Fee, also known as Trelfa, and her civil partner Nyomi Fee, 30, were both convicted of grossly abusing their position of trust to inflict appalling suffering on the child after subjecting him to a ''cruel and pitiless regime'' of abuse and neglect.

He had suffered fatal heart injuries similar to those found on road crash victims and spent the last few days of his short life in agony from an untreated broken leg and fractured arm.

The pair - originally from Ryton, Tyne and Wear - were also convicted of being behind a catalogue of unspeakable cruelty against two boys in their care, one of whom they tried to blame for Liam's death.

Judge Lord Burns last year handed both women life sentences and ordered Rachel Fee to serve a minimum of 23-and-a-half years behind bars, while "domineering" Nyomi Fee was told to spend at least 24 years in prison.

Rachel Fee appeared alone in the dock on Friday as her defence counsel set out her full appeal case, centred on what they say was a misdirection by the trial judge during his legal summing-up at the High Court in Livingston in May.

Defence QC Brian McConnachie told the court the judge had directed the jury that they could convict both women of murder, acquit both accused, or convict Nyomi Fee of murder and acquit Rachel Fee.

"But what he did not present to the jury was the possibility that they could convict Nyomi Fee of murder and convict the appellant (Rachel Fee) of culpable homicide," Mr McConnachie said.

The lawyer submitted that there was a case, on the evidence, for the jury to identify co-accused Nyomi Fee as having been the main "actor" in committing the murder.

"It was important to give the jury the option, in my submission, to convict the appellant (Rachel Fee) of something less than murder, on the basis that she had not signed up to such a criminal purpose," Mr McConnachie said.

Advocate depute Alex Prentice QC, for the Crown, argued it was a "clear case in which the Crown had established concert for murder".

He added: "The indictment was drafted to set out the allegations of a long-term course of serious cruel treatment of the children."

He pointed to evidence about untreated bone fractures suffered by Liam, internet searches made about it on the accused's phones, evidence that Liam had been losing weight, and that people had been encouraged not to interact with the child.

"The Crown case is one of murder against both," Mr Prentice said.

"There was no room for culpable homicide."

Lord Justice Clerk Lady Dorrian, sitting with Lord Turnbull and Lord Bracadale, said the judges would take time to consider the arguments and deliver their decision at a later date.