Cervical spinal nerves-- special anatomic aspects to consider

1. The ventral rami of C1-C4 form the cervical plexus, and C5-C8 the brachial plexus.

2. Exceptionally, C1 spinal nerve divides WITHIN the spinal canal to form a ventral and dorsal ramus, that passes above the arch of C1 to supply the deep muscles of the neck, without sensory fibers. The ventral ramus joins the cervical plexus.

3. The C2 root is very short. The ventral ramus joins the cervical plexus. C2 may project to the brow, whereas pain the back of the head is more likely cervical plexus. The dorsal ramus passes between C1 and C2 and the larger medial branch becomes the greater occipital nerve (C2 dorsal ramus). The lateral branch subserves the paraspinal muscles. That supplies the back of the head. C3,4,5, T1 dorsal rami affect skin on back of the neck.

4. The four cutaneous branches are the greater auricular, lesser occipital, supraclavicular, and transverse cutaneous nerves of the neck. They all emerge from the posterior border of the sternocleidomastoid muscle into the posterior triangle of the neck.

Lesser occipital nerve (C2-3 ventral ramus) affects the skin behind the ear. It affects the lower posterior occiput whereas the greater occipital affects anteriorly.

The greater auricular nerve (C2-3 ventral ramus) affects the skin below and directly behind the ear. Preauricular nerve overlaps trigeminal distribution, pain is dull aching not lancination. Posterior auricular nerve innervates the posterior occiput, mastoid, most of the pinna and posterior parietal area.

The transverse cutaneous nerve (C2-3 ventral ramus) of the neck affects the skin of the neck.

The supraclavicular nerve (C3-4 ventral ramus)affects the skin on top of the shoulder.

5. The phrenic nerve (C5) is the major muscular branch of the cervical plexus.

6. The spinal root of the accessory nerve derives from anterior horn cells and ascends the cord through the foramen magnum and leaves it throught the jugular foramen, together with the IX and X cranial nerves.

More pearls:
1. TMJ and cervical plexus pain may coexist in young patients due to cervical plexus
2. Difficulty swallowing ("pain stuck in my throat") may be due to spasm of cricopharyngeus muscle (external esophageal sphincter) and dyssynergia of posterior pharyngeal muscles (X nerve) that pushes the bolus to the cricopoharyngeus muscle that fails to open rapidly enough.