A surgical instrument comprising: an element connectable with a fixture; a first member independently and selectively movable relative to the element and including a first part engageable with an incision in a cranial-caudal orientation relative to a body to space apart tissue; a second member independently and selectively movable relative to the element and including a second part engageable with tissue of an anterior portion of the incision; and a third member independently and selectively movable relative to the element and including a third part engageable with tissue of a posterior portion of the incision, wherein the parts (80, 170, 204) are disposable in a configuration to space tissue of the incision to define an oblique surgical pathway relative to a bilateral axis of the body, characterized in that at least one of the members (30, 32, 34) includes an adaptor (430; 630; 830) disposed between the member (30, 32, 34) and the part (80, 170, 204), the adaptor (430; 630; 830) including a moveable ramp interface such that the part (80, 170, 204) is releasably engageable with the member (30, 32, 34) and including a housing (432; 632; 832), wherein the adaptor (430; 630; 830) includes a quick release connection including a push button (440; 640; 840) release, and wherein the button (440; 640; 840) further comprises extensions (480, 482; 680, 682; 880, 882) extending into the housing, wherein one of the extensions comprises a surface forming a ramp of the movable ramp interface and the other extension (482; 682; 882) comprises a cavity (504; 704; 902) configured for disposal of an alignment pin (506; 706; 904) configured to facilitate alignment of the button (440; 640; 840) with the housing (432; 632; 832). an element connectable with a fixture; a first member independently and selectively movable relative to the element and including a first part engageable with an incision in a cranial-caudal orientation relative to a body to space apart tissue; a second member independently and selectively movable relative to the element and including a second part engageable with tissue of an anterior portion of the incision; and a third member independently and selectively movable relative to the element and including a third part engageable with tissue of a posterior portion of the incision, wherein the parts (80, 170, 204) are disposable in a configuration to space tissue of the incision to define an oblique surgical pathway relative to a bilateral axis of the body, characterized in that at least one of the members (30, 32, 34) includes an adaptor (430; 630; 830) disposed between the member (30, 32, 34) and the part (80, 170, 204), the adaptor (430; 630; 830) including a moveable ramp interface such that the part (80, 170, 204) is releasably engageable with the member (30, 32, 34) and including a housing (432; 632; 832), wherein the adaptor (430; 630; 830) includes a quick release connection including a push button (440; 640; 840) release, and wherein the button (440; 640; 840) further comprises extensions (480, 482; 680, 682; 880, 882) extending into the housing, wherein one of the extensions comprises a surface forming a ramp of the movable ramp interface and the other extension (482; 682; 882) comprises a cavity (504; 704; 902) configured for disposal of an alignment pin (506; 706; 904) configured to facilitate alignment of the button (440; 640; 840) with the housing (432; 632; 832).