Eva Amurri Martino's son's skull was cracked when a night nurse dropped him.

Susan Sarandon’s daughter, Eva Amurri Martino, has shared an account of how her then six-week-old son, Major James, was dropped on his head.

The 31-year-old told readers of her blog, Happily Eva After, that Major cracked his head open after slipping from the arms of his night nurse.

“A couple of days after Thanksgiving, our night nurse fell asleep while holding Major and dropped him, and he cracked his head on the hardwood floor,” she wrote.

“Kyle and I were sleeping at the time and were awoken by the sound of his head hitting the floor, and then hysterical piercing screams.”

A photo posted by HAPPILY EVA AFTER (@thehappilyeva) on Nov 24, 2016 at 7:27pm PST

The mother-of-two explained how despite the severity of his injuries, he was pronounced as fit to return home after two days in hospital.

“He suffered a fractured skull and bleeding on his brain, and was transported by ambulance to Yale Medical Center where I spent two harrowing days with him to receive emergency care and further testing,” she wrote.

“Though he had the fracture, some skull displacement, and bleeding, the skull did not touch his brain and the bleeding was localized.

“Further MRI’s showed no brain damage and we were discharged by experts in pediatrics and neurology with as excellent of a prognosis as we could have ever hoped for.”

A photo posted by HAPPILY EVA AFTER (@thehappilyeva) on Nov 29, 2016 at 6:29am PST

The actress shared how she blamed herself for not preventing the accident.

“There will always be the people who say that this accident was my fault. That if it had been me in there holding him instead of a night nurse, that this never would have happened,” she wrote.

“The guilt I bore in the days and weeks after this accident was more intense and more damaging than anything I would wish upon my worst enemy.”

Eva said the memory of the incident still affects her on a daily basis.

“Even though I finally made peace with the fact that this freak accident could not have been avoided by me, it has continued to effect me to my core and in all aspects of my daily life,” she wrote.

The mother-of-two spoke about how even the cries of her son still trigger vivid memories of the event.

"Hearing Major cry hard immediately triggers my memories of the moments after the accident and instigates an immediate panic attack– my heart races and tears spring to my eyes," she wrote.

"Sometimes I get dizzy spells. I feel nauseous and overwhelmed and even small discomforts he has make me anxious."

Major is now said to be safe, well and thriving beside older sister, Marlow Mae. Major and Marlowe, two, are the only two children shared by Eva and husband of five years, Kyle Martino.

The actress said she can no longer allow a nanny into her home at night but still allows assistance during the day.