Where Do the Phrenic Nerves Arise From?


Quick Answer

Both phrenic nerves arise from the C3, C4 and C5 nerve roots in the cervical spine at the back of the neck, according to Radiopaedia.org. The right and left phrenic nerves are sensory and motor nerves that control movement of the diaphragm muscle in the abdomen below the ribcage.

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Full Answer

The right phrenic nerve enters the abdominal cavity after passing near the superior vena cava and the right side of the heart. The left phrenic nerve passes near the arch of the aorta and the left side of the heart. Both nerves descend from the thorax of the neck before heading near the heart to the diaphragm, notes Radiopaedia.org. Each phrenic nerve branches into three smaller nerves upon reaching the abdominal cavity. These nerves are the sole motor coordination apparatus of the diaphragm. Smaller branches of the phrenic nerves also control the covering of the heart known as the pericardium.

Eight cervical nerve roots control several important body parts, including the head, diaphragm, upper body muscles, arms and hands, according to Spine-health. Cervical nerves branch off from the spinal cord in the neck to produce several smaller nerves. The top two nerves, C1 and C2, control movements of the head. Cervical nerves C3 and C4 extend to the diaphragm, whereas C5 helps control the shoulders and upper arms. Cervical nerves C6, C7 and C8 provide nerves for motor control of the forearm.

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