What Part Of Brain Cause Short Term Memory Loss?

Causes of short term memory loss. What part of brain is affected if it is physical. Can it be both physical and mental. I also have been diagnosed with PTSS. suffer from anxiety and depression since 16 yrs old caused by a Chemical imbalance. Trauma to brain from falling 3 stories. Also from being hit by an automobile at a fast speed while walking. Multiple concussions in life time. Other brain trauma.