Abstract: An arm support including a mounting bracket configured to mount the arm support to a supporting structure, a track supported by the mounting bracket, a forearm support configured to support a forearm of a user, a linear bearing allowing a first degree of freedom of movement for the forearm support, a rotary bearing allowing a second degree of freedom of movement for the forearm support, and a gimbal joint allowing a third degree of freedom of movement for the forearm support.

Abstract: A seating structure includes a base, a seat supported by the base, and a backrest having a frame and a suspension material supported by the frame. The frame includes an upper end and a lower end opposite the upper end. The seating structure also includes an upper thoracic support assembly supported by the frame adjacent the upper end. The upper thoracic support assembly including a thoracic support pad positioned between the frame and the suspension material. The thoracic support pad configured to engage the suspension material to support an upper thoracic region of a user.