The video explains that each heart pumps blood through the same system, so one’s actions can affect the other. Despite sharing blood circulation, their individual brains and spinal cords work independently, coordinating movements for their respective body sides.
Abby controls the right arm and Brittany the left, and it’s the same for their legs. But even with this ‘division’, their movements are highly coordinated.
For tasks like holding objects that need both arms, they rely on constant cooperation and communication. The video says they can do these tasks smoothly because of the great synchronization between their two brains and nervous systems. Their skeletal systems, including two separate spines joined at the pelvis, maintain independent neurological functions.
Each twin has two lungs, four in total. While the medial lungs are fused to some degree, the outer ones work independently.