Question

Where is referred pain most likely to go from irritation to the mediastinal pleura of the middle mediastinum?

1) To the right shoulder
2) To the left shoulder
3) To the neck
4) D) To the abdomen

Answer 1

Referred pain from irritation to the mediastinal pleura of the middle mediastinum is most likely to be felt in the left shoulder. This is due to the shared spinal cord levels between visceral sensory fibers of the mediastinum and somatosensory fibers from the shoulder, leading to misinterpretation of the origin of pain by the brain.

Step-by-step explanation:

When considering irritation to the mediastinal pleura of the middle mediastinum, the most likely location for referred pain is the left shoulder. This phenomenon occurs because visceral sensory fibers from the mediastinum, which contains major internal organs like the heart, enter the spinal cord at the same level as the somatosensory fibers that innervate the shoulder and arm. Therefore, the brain may misinterpret the sensations originating from the mediastinum as being from the shoulder area due to shared neural pathways.

Examples of referred pain include Kehr's sign where rupturing of the spleen may cause referred pain in the left shoulder, chest, and neck regions. The explanation for Kehr's sign involves the spleen being located just inferior to the diaphragm in the upper-left quadrant of the abdominopelvic cavity, leading to pressure on the diaphragm and subsequent referred pain in corresponding regions related to the diaphragm's innervation levels.