A retractor in accordance with embodiments of the invention comprises a retractor element and a retractor arm releasably connectable to the retractor element. A first connector structure on the retractor arm includes a first end portion having a first edge, a first pin slot extending into the first end portion from the first edge, and a first lock well in the first pin slot. A second connector structure on the element includes an end portion having an aperture, the end portion configured to receive the first connector structure at a connected position with the aperture aligned with the first lock well of the first connector structure. The lock includes a first cam and is rotatable between a release position and a lock position. The cam is configured such that (1) when the lock is in the release position the end portion of the second connector structure can be moved to the connected position with respect to the first connector structure with the first cam passing through the first pin slot and into the first lock well of the first connector structure, and (2) when the lock is in the lock position the first cam engages the first end portion of the first connector structure to resist withdrawal of the first end portion of the first connector structure from the second connector structure.
