Final answer:
To best demonstrate the left intervertebral foramen in the cervical vertebral column, the CR should be angled 15-20 degrees cephalad in the lateral view.
Step-by-step explanation:
The left intervertebral foramen can be best demonstrated in the cervical vertebral column when the CR (central ray) is angled 15-20 degrees cephalad (towards the head) in the lateral view. The intervertebral foramen is the opening between adjacent vertebrae that allows for the passage of spinal nerves.
In the cervical vertebral column, each vertebra has a transverse process, and within each transverse process is an opening called the transverse foramen. The transverse foramina of adjacent vertebrae align to form the intervertebral foramen.
So, to best demonstrate the left intervertebral foramen, the CR should be angled cephalad in the lateral view of the cervical vertebral column.