A coupling mechanism includes a base and a lever. The base is configured to couple to an external fixture. The lever is pivotably coupled to the base and transitionable between a clamped configuration and an unclamped configuration. A first pair of opposed arms extends from the base and a second pair of opposed arms extends from the lever in opposed relation to the first pair of opposed arms. In the clamped configuration the second pair of opposed arms are proximate the first pair of opposed arms, and in the unclamped configuration the second pair of opposed arms are spaced apart from the first pair of opposed arms. At least one of the first pair of opposed arms or the second pair of opposed arms includes a step thereon. The step is configured to receive and retain a surgical tool therein in the clamped configuration.