From the long corridor of people came a roar that built into a crescendo. "We've got a winner," the man to the right yelled. The radio reports had been right, for striding down the asphalt, flanked by police motorcycles, was Neil Cusack of East Tennessee State, eating up the last few yards. Far above, the Prudential Center loomed in the suddenly grey sky as the crowd whistled and screamed its approval.

The bearded 22-year-old in the green mesh T-shirt wearing number 16 became the 78th winner of the Boston Marathon yesterday. The Irish-born Cusack ran away from the pack to finish the 26-mile, 385-yard course in 2:13:39, the second fastest victory ever for the B.A.A. event.

Also covering those last few yards was Mike Burns, a red-headed sophomore from Martinsville, Va., who finished in 2:41:06 and placed 177th. Burns and three other runners staying at Harvard, who attend Washington and Lee University in Lexington, Va., lasted the grueling 26 miles. Tom Washington, a late arrival in Cambridge, placed 185th and was only 4.6 seconds behind Burns. Bill Kalal ran a 2:53:54, his best ever, and copped the 416th spot.

From Harvard, senior Mike Bernick came in 22 minutes and nine seconds after the hour of three o'clock. Harvey Inashima, another senior, pulled in with a 3:14:07, and Tom McElligott notched unofficially a four-hour mark. James Bailey, a tutor in Eliot House, pulled into the Pru after roughly three hours and 28 minutes.

The tension had grown as the afternoon progressed. The large crowd packed the Boylston side of the Prudential Building as three helicopters swirled and buzzed above in the sunny sky, and as two o'clock came and passed, the crowd constantly pressed forward into the street. The police continually pushed it back.

Then came Cusack, who missed beating the course record set by England's Ron Hill in 1970 of 2:10:30. Following Cusack came runner after runner, of all sizes and shapes, some grinning, others with faces contorted in pain. Tom Fleming, an American from William Patterson College in New Jersey was second, and then no one seemed to keep count.

"I can't even run for five blocks without starting to pant," one woman bystander said, in awe of the straining marathoners in front of her. To the right, a man explained to his son that this year Americans were winning.

"That's it," he said as Fleming pass, "more Americans. We'll show them in '76."

The runners began to appear in clumps of two or three. There were two quick backstretch duels that excited the crowd as runners drew on hidden reserves of strength to challenge each other.

And then Burns appeared, moving smoothly through the last few hundred feet. After crossing the finish line he followed the other exhausted marathoners to the escalators leading to the Prudential Center.

Many of the marathoners couldn't stand on their own and had to be held up on either side by friends. Others sought the shelter of a warm blanket. Some were in true agony, clutching at their sides and coughing violently. Burns, and later Kala, walked away without faltering. But on all of their faces was a dazed look. Burns accepted congratulations and moved off, seemingly unaware of his surroundings.

"The emotion of the crowd carried me the last thee or four miles," Burns said later, the fatigue showing around his eyes. When asked if he would return next year to run in the marathon, he indicated that he wouldn't. "I'm really down on it. I'm drained physically and mentally."

Burns and Kalal were also impressed by the spectators. Ferris Mack, a freshman from Washington and Lee who didn't finish the race, talked about the lift he got from the girls who lined the streets in Wellesley.

Ferris stopped at the 25-mile mark. "I was dying," he said afterwards. "I had stopped and my legs cramped up."

If there was disappointment for Mack, there was accomplishment for Mike Brittin of W & L, a former defensive safety who put himself in an ambulance to qualify for the marathon. Brittin, in the space of two months, has dropped his time from roughtly four hours to the 3:20's--an incredible feat.

For all those who an yesterday--Brittin, Bernick, Kalal, Inashima and McIlligott--there was perhaps the thought expressed by Burns during a weekend interview.

"Anyone who finishes a marathon wins," Burns had said. "The great thing about running is that you can win without finishing first."