Why is there a C8 nerve?
In the cervical spine, the nerves exiting the spinal cord are named for the inferior vertebrae. For example, C3 exits between C2 and C3.
Then between C7 and T1, there is a C8 nerve.
And subsequently, nerves are named for the superior vertebrae. For example, T2 exits between T2 and T3.
I haven't heard a reasonable explanation for why this is done, besides to confuse medical students.