Roger Sylvester, 30, was placed on a life-support machine and died a week later.
He had been held by eight officers after they found him naked and causing a disturbance in Tottenham, north London. He was taken, still naked, to St Ann's Hospital in north London in a police van.
Cuts and abrasions found on Mr Sylvester's body and face were probably caused by him rolling around on concrete and undergrowth, St Pancras coroner's court in London was told.
The affair is seen as an important test case of how the police treat black people while in custody.
The father of Stephen Lawrence, the murdered black teenager, has already given his support to the parents of Mr Sylvester. A 600-strong crowd marched to Tottenham police station on Saturday.
Detective Superintendent Steve Reynolds, from Essex Police, the outside force brought in to investigate the case, told the inquest: "Initially, he was seen by a doctor, although I have to say the clarity of this stage of the investigation is not clear. (The doctor) had to leave the room to seek some sort of advice or treatment and the officers continued to restrain him.
"At some stage during this, Mr Sylvester went all limp and it was obvious that he had collapsed. The police officers then commenced to resuscitate Mr Sylvester and they were assisted [by] medical staff."
Earlier Det Supt Reynolds said police were called to Mr Sylvester's home to answer a 999 call at 9.37pm on 11 January, the caller reporting that a man was acting "very, very strangely". Two officers arrived at Summerhill Road in a police car and found a man naked and throwing himself on the ground, the court heard. They called for assistance and were joined by four officers in a van and two in a car.
"They restrained the man and at least one of the officers recognised the man as Roger Sylvester and was aware Mr Sylvester had suffered mental problems in the past," said Det Supt Reynolds.
Mr Sylvester, a part-time administrative assistant at a council-run day centre, was detained under the Mental Health Act and taken to St Ann's Hospital.
After the resuscitation attempts Mr Sylvester was transferred to the North Middlesex Hospital, then the intensive care unit at the Whittington Hospital, north London, where he later died.
Freddy Patel, a pathologist who performed an autopsy, said Mr Sylvester - 181/2st and 5ft 10in - had marks consistent with his hospital treatment and "various injuries".
He said: "These were mainly superficial grazes, all in the healing stages, consistent with him being naked and falling on to the ground and coming into contact with rough surface or shrubbery."
These injuries "in no way" contributed to his death.
But the pathologist said he was unable to establish a cause of death and he is awaiting the results of further tests, particularly on the heart and brain. Marks found around Mr Sylvester's wrists were probably caused from the attempts to resist handcuffing, the pathologist said.
The inquest was adjourned to a date to be fixed.Reuse content