The jury in the trial of seven people accused of the sexual abuse of three children has heard that they were seriously neglected and were sexually abused by their parents and relatives over a number of years.

The parents of the three children also face charges of neglecting five of their children.

Opening the case, prosecuting counsel Bernard Condon gave the jury a chart detailing the various family members involved in the case.

The seven on trial include the children's parents, a grandmother and uncles and aunts.

All seven have denied the charges.

Mr Condon told the jury the case would involve really difficult events and allegations of the most difficult kind made by very young children against people who are the closest to them in their lives.

He said the children involved were "badly let down by the people on this chart".

Mr Condon said it was undoubtedly a sad case, but told the jury they must not decide the case based on emotion and should instead use rationale and reason when assessing the evidence before them.

He outlined the various sexual offences alleged by the children, including rape, section 4 rape and sexual assault and told the jury the charges were sample charges.

Mr Condon told the jury the three children who have made allegations of sexual abuse are now aged 14, 12 and 11.

The offences are alleged to have taken place between 2014 and 2016 and are sample charges where the children have alleged the offences took place a number of times.

Two of the children have given interviews to specialist gardaí and DVD recordings of these interviews will be played to the jury. Another will give evidence by video link.

Mr Condon said the children were taken into foster care in 2016 and they will hear evidence from various foster parents about their poor condition when they arrived into care.

They will hear how the children had difficulty with hygiene and dental care and how one required glasses but was not wearing them.

One child was described as being thin and wearing dirty clothing.

Mr Condon said they would also hear evidence about their home life from social workers who paid visits to the children's home and from a neighbour who witnessed events, such as one child defecating and urinating on the footpath outside her home.

They will also hear evidence from teachers who became concerned about the children. There will be evidence about the children being "lined up" by their father and given medication that had not been prescribed for them.

The jury was told the children lived in close proximity to other relatives who are also on trial for sexually abusing them.

The trial is expected to last at least eight weeks and an enlarged jury of 15 people has been sworn in to hear the evidence.

The trial is being heard in temporary courtroom facilities at Croke Park to allow for social distancing.

The case is being heard "in camera" and is not open to the public.

The jury has already been told the seven on trial include the children’s parents and members of their extended family. The parents also face charges of neglect in relation to a total of five children.

It took more than an hour for 91 charges to be read out at the Central Criminal Court last Thursday afternoon.

It is alleged that some of the children were assaulted by being medicated and that they were made to engage in sexual activity with other children and adults.

Each of the seven defendants has pleaded not guilty to the offences, which are alleged to have happened between 2014 and 2016.

Mr Justice Paul McDermott told the jury neither the children nor the accused can be identified at any stage.

The children's father has pleaded not guilty to 34 charges, including rape, sexual assault, sexual exploitation, assault and neglect of his children.

His wife has pleaded not guilty to 25 charges, including sexual assault, sexual exploitation and assault, including allowing the children to be sexually assaulted by others. She also faces charges of neglect.

Another man, aged 48, has denied 12 charges, including rape, sexual assault and sexual exploitation of three of the children.

A 35-year-old woman has pleaded not guilty to three charges of sexual assault of two of the children.

A 27-year-old man has pleaded not guilty to ten charges, including rape, sexual assault and sexual exploitation.

A 32-year-old woman has pleaded not guilty to four charges, including sexual assault and sexual exploitation of two of the children.

A 57-year-old woman has pleaded not guilty to three charges of sexual assault.

This afternoon the jury was shown two recordings of an interview with one of the children, a now 12-year-old girl. She was nine years old when the videos were recorded with a specialist garda interviewer.

She described being sexually abused by various family members including her parents, uncles and aunts in front of her siblings and cousins on different occasions in different locations.

She also described her father and uncles having sex with her on different occasions and said she thinks she would have been five, six or seven at the time. She said it felt "weird".

She described "doing sex" with her brothers at their home.

The jury will continue viewing the recorded interviews tomorrow.