Cervical spinal nerve 8

The cervical spinal nerve 8 (C8) is a spinal nerve of the cervical segment.
It originates from the spinal column from below the cervical vertebra 7 (C7).
Innervation.
The C8 nerve forms part of the radial and ulnar nerves via the brachial plexus, and therefore has motor and sensory function in the upper limb.
Sensory.
The C8 nerve receives sensory afferents from the C8 dermatome. This consists of all the skin on the little finger, and continuing up slightly past the wrist on the palmar and dorsal aspects of the hand and forearm. Clinically a test of the pad of the little finger is often used to assess C8 integrity.
Motor.
The C8 nerve contributes to the motor innervation of many of the muscles in the trunk and upper limb. Its primary function is the flexion of the fingers, and this is used as the clinical test for C8 integrity, in conjunction with the finger jerk reflex.
The particular muscles receive innervation from C8 (shown by specific nerve and spinal nerve segments; muscles in italics only have a minor contribution from C8) :