A surgical stapling apparatus, comprising: a housing; a handle supported by the housing; an elongated body extending distally from the housing; a tool assembly at the distal end of the elongated body, the tool assembly having a cartridge assembly including a cartridge having a plurality of surgical fasteners therein, and an anvil assembly in juxtaposed relation to the cartridge assembly, at least one of the cartridge assembly and anvil assembly being movable in relation to the other of the cartridge assembly and anvil assembly, the cartridge assembly having a tissue contacting surface and the anvil assembly having a tissue contacting surface, wherein the anvil assembly includes: an anvil plate defining a pair of opposed distal side recesses for receiving a first anchor and a pair of opposed proximal side recesses for receiving a second anchor; a buttress releasably secured to the tissue contacting surface of the anvil assembly by the first anchor and the second anchor; and a drive assembly slidably translatable through the tool assembly from a proximal position to a distal position, characterized in that at least one of the pair of distal side recesses and the pair of proximal side recesses is keyhole-shaped such that it has a central portion (570d 1,570e 1), a widening mouth portion (570d 2, 570e 2) disposed at one end of central portion (570d 1,570e 1) and open on a side edge of the anvil plate, and an enlarged head portion (570d 3,570e 3) disposed at an opposite end of the central portion (570d 1,570e 1). a housing; a handle supported by the housing; an elongated body extending distally from the housing; a tool assembly at the distal end of the elongated body, the tool assembly having a cartridge assembly including a cartridge having a plurality of surgical fasteners therein, and an anvil assembly in juxtaposed relation to the cartridge assembly, at least one of the cartridge assembly and anvil assembly being movable in relation to the other of the cartridge assembly and anvil assembly, the cartridge assembly having a tissue contacting surface and the anvil assembly having a tissue contacting surface, wherein the anvil assembly includes: an anvil plate defining a pair of opposed distal side recesses for receiving a first anchor and a pair of opposed proximal side recesses for receiving a second anchor; a buttress releasably secured to the tissue contacting surface of the anvil assembly by the first anchor and the second anchor; and a drive assembly slidably translatable through the tool assembly from a proximal position to a distal position, characterized in that at least one of the pair of distal side recesses and the pair of proximal side recesses is keyhole-shaped such that it has a central portion (570d 1,570e 1), a widening mouth portion (570d 2, 570e 2) disposed at one end of central portion (570d 1,570e 1) and open on a side edge of the anvil plate, and an enlarged head portion (570d 3,570e 3) disposed at an opposite end of the central portion (570d 1,570e 1). an anvil plate defining a pair of opposed distal side recesses for receiving a first anchor and a pair of opposed proximal side recesses for receiving a second anchor; a buttress releasably secured to the tissue contacting surface of the anvil assembly by the first anchor and the second anchor; and a drive assembly slidably translatable through the tool assembly from a proximal position to a distal position, characterized in that at least one of the pair of distal side recesses and the pair of proximal side recesses is keyhole-shaped such that it has a central portion (570d 1,570e 1), a widening mouth portion (570d 2, 570e 2) disposed at one end of central portion (570d 1,570e 1) and open on a side edge of the anvil plate, and an enlarged head portion (570d 3,570e 3) disposed at an opposite end of the central portion (570d 1,570e 1).