You can create a view with the below filter options,
Assigned To is equal to [ME]
Created By is equal to [ME]
So in this view, only the items in which the current logged in user is in "Assigned To" column or "Created By" column will only be displayed. This is a simple way to display item in which current logged in user is related to. There is another ...
First of all create one Person or Group Field in your list (If you don't have it), say you named it Assigned To.
As you are using SharePoint 2010, you can create a SharePoint designer 2010 workflow and use Replace List Item Permissions action to manage the list item permissions.
Workflow actions in SharePoint Designer 2010: A quick ...