The lesser auricular nerve originates from the cervical plexus

Cervical plexus

The cervical plexus is a plexus of the ventral rami of the first four cervical spinal nerves which are located from C1 to C4 cervical segment in the neck. They are located laterally to the transverse processes between prevertebral muscles from the medial side and vertebral from lateral side...

, composed of branches of spinal nerve

Spinal nerve

The term spinal nerve generally refers to a mixed spinal nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body...

s C2 and C3.

The Great auricular nerve runs posteriorly to the ear, and is "greater" since it provides most of the innervation to the ear: the back of the ear, front of the ear and earlobe. The rest is provided by the auriculotemporal nerve, which supplies the skin anterior to the external auditory meatus.