Question

The phrenic nerve may be damaged where it descends along the neck or during open thorax or open heart surgery. Explain how damage to the right phrenic nerve affects the diaphragm. Describe
the effect on the diaphragm of completely severing the spinal cord in the thoracic region (below the exit point of the phrenic nerve)
versus in the upper cervical region (above the exit point of the phrenic nerve).​

Answer 1

Answer:

The phrenic nerve is a mixed motor/sensory nerve which originates from the C3-C5 spinal nerves in the neck. The nerve is important for breathing because it provides exclusive motor control of the diaphragm, the primary muscle of respiration. In humans, the right and left phrenic nerves are primarily supplied by the C4 spinal nerve, but there is also contribution from the C3 and C5 spinal nerves. From its origin in the neck, the nerve travels downward into the chest to pass between the heart and lungs towards the diaphragm.

In addition to motor fibers, the phrenic nerve contains sensory fibers, which receive input from the central tendon of the diaphragm and the mediastinal pleura, as well as some sympathetic nerve fibers. Although the nerve receives contributions from nerves roots of the cervical plexus and the brachial plexus, it is usually considered separate from either plexus.

The nerve is named from the Ancient Greek phren, meaning diaphragm.[1]

Explanation:

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