Phrenic Nerve, Anterior View

Description

Originating from the anterior rami of C3 to C5, the phrenic nerve descends in the anterior neck on the anterior surface of the scalenus anterior muscle, deep to the prevertebral fascia and medial to the sternocleidomastoid. Inferiorly it approaches the thoracic inlet, crossing toward the root of the neck in close company with the carotid sheath contents, including the common carotid artery and internal jugular vein. The clavicles form the inferior boundary of the field, while adjacent cervical nerve elements are shown as a yellow neural network around the lateral neck. For teaching and procedural planning, this anterior perspective clarifies the phrenic nerve’s relationship to scalenus anterior, a frequent landmark during interscalene brachial plexus block and supraclavicular approaches. Ipsilateral hemidiaphragmatic paresis from phrenic nerve blockade is a predictable complication, and this view helps explain why local anesthetic spread anterior to the brachial plexus can capture the nerve. It also supports discussions of traction or compression neuropathy at the thoracic inlet and the nerve’s vulnerability during anterior cervical or neck dissections. Use this illustration in gross anatomy and neuroanatomy courses when you need a clean depiction of cervical nerve topography, and in anesthesia or regional block teaching materials that address diaphragm-sparing techniques. It also fits operative anatomy chapters on the anterior triangle of the neck and complications of cervical procedures. Anatomical accuracy verified by SciePro's Medical Advisory Board.