General Medical Information

Inferior Portion of the Neck

Susan D. John
Michael D. Maves

In the inferior root of the neck and closely associated with the brachial plexus are the paired phrenic nerves that course medially to innervate the diaphragm. These nerves originate in the ventral rami of the cervical plexus of the third, fourth, and fifth cervical nerve rootlets. The subclavian artery gives rise to the thyrocervical trunk. The transverse cervical and suprascapular arteries typically course laterally over the surface of the phrenic nerve. This relation allows identification of these structures. The vagus nerve lies further medially and is contained within the carotid sheath. It shares the sheath with the common, internal, and external carotid arteries and jugular vein. Posterior to the carotid sheath lies the cervical sympathetic nerve. On the surface of the carotid sheath lie the ansa hypoglossi nerves.