Final answer:
The ansa cervicalis is made up of ventral rami from the C1 to C3 cervical segments of the spinal cord, forming part of the cervical plexus which serves the neck and head.
Step-by-step explanation:
The ansa cervicalis is constituted by the ventral rami from the C1 to C3 cervical segments. These rami come together to form a loop that innervates several muscles in the anterior region of the neck, such as the sternohyoid, omohyoid, and sternothyroid muscles. It is important to understand the cervical plexus, which originates from the axons of spinal nerves C1 through C5, and provides motor and sensory innervation to structures of the neck and head. Notably, the cervical enlargement region in the anterior horn of the spinal cord harbors a larger population of neurons essential for providing a greater level of control over the fine musculature of the upper limbs, specifically the hands and fingers.