A device for supporting a patients arm includes a rail clamp configured to be secured to a rail or other structure on a table such as an operating table. The rail clamp includes a clamp body and a socket configured to receive a base of an attachment such as a support arm or lateral brace. The base may be inserted longitudinally in the socket on the rail clamp. A stabilizer bar extends from the base in some embodiments. The base is moveable in the socket such that the stabilizer bar may be raised or lowered relative to the rail clamp. One or more modular attachments for supporting various regions of a patients arm may be secured to the stabilizer bar or the rail clamp.
