A surgical apparatus includes an implant for mutually supporting an upper spinous process of a first vertebral body and a lower spinous process of a second vertebral body. The implant comprises a first implant component and a second implant component movable relative thereto along a clamping direction to transfer the implant out of a basic position in a spreading direction that is oriented transversely relative to the clamping direction into a spread position. The implant includes at least one introduction-side upper supporting element and at least one introduction-side lower supporting element that for laterally supporting the upper spinous process or the lower spinous process on the introduction-side. A fixing device for the implant is used for spreading the at least one introduction-side upper supporting element and the at least one introduction-side lower supporting element relative to each other along the spreading direction in an introduction position of the implant.
