Ballymena extended their unbeaten run under new manager David Jeffrey to five games by beating Dungannon Swifts 4-2 to move into seventh spot in the table.
Darren Boyce (2), Kyle McVey and Jonny Frazer scored for United, with Jamie Glackin and Andy Mitchell replying.
Warrenpoint Town are a point adrift at the bottom of the table after a 1-1 draw with Carrick Rangers at Milltown.
Adam Salley scored on the hour mark but Stephen Murray levelled with a penalty on 82 as both sides ended with 10 men.
The impressive Salley met a good cross from the right with a fine finish, but Murray's late spot-kick earned the league's basement side a point they barely deserved.
Mark Clarke had been sent-off for a second yellow card offence in the 57th minute, while Aaron Smyth was dismissed in the 73rd.
Mallards and Ports in scoreless draw
Ballinamallard are also still in the relegation mire despite clinching a scoreless draw with fellow strugglers Portadown at Shamrock Park.
The Ports had lost seven of their last eight league games, while the Mallards had tasted defeat in each of their last three top flight outings.
Portadown's best chance of the game fell to Gary Twigg in the first half but his header from a Chris Casement cross was kept out by visiting stopper Stefan McCusker.
Sky Blues get off to flying start
Ballymena led 4-1 after a hectic first half at Stangmore Park, with Andy Mitchell missing a succession of chances before grabbing a consolation goal four minutes into added time.
Henderson opened the scoring in the sixth minute with a close-range header after Frazer's initial headed effort had cannoned off the bar.
McVey lashed home through a body of players for his fourth goal of the season 10 minutes later after the Swifts defence failed to clear from a corner.
Glackin converted a simple finish from an Andrew Burns delivery on 22 but Henderson restored his side's two-goal advantage when he raced onto a Willie Faulkner through ball, beat the offside trap and slotted home.
Frazer met a Tony Kane cross to nod home his first goal for the club since agreeing a loan move from Linfield in January 10 minutes before the interval.
|Danske Bank Irish Premiership results|
|Dungannon Swifts||2-4||Ballymena United|
|Warrenpoint Town||1-1||Carrick Rangers|