Find the testcases within a testcycle via the Zephyr Scale Cloud API

I want to insert an test execution result for a testcase via the API but the endpoint for adding a new test execution requires the testcycle key. I've tried to see how I can find the association between the testcase and the testcycle in both the testcase and the testcycle by getting each. I was hoping the testcase would have a reference to the testcycle or the testcycle would have a list of all its testcases. Neither appears to be true. I use the following to retrieve the

testcase: https://api.zephyrscale.smartbear.com/v2/testcases/<testcaseid>

testcycle: https://api.zephyrscale.smartbear.com/v2/testcycles/testcycles/<testcycleid>

Neither of these call return information relating to the other even though the testcycle contains the testcase.

I don't understand how I can create a test execution without this information. Any guidance would be appreciated.

TIA Alan