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Ch. 13 The Peripheral Nervous System and Reflex Activity
Hoehn - Marieb Human Anatomy & Physiology, 12th edition
Hoehn, Haynes, Abbott12th EditionMarieb Human Anatomy & PhysiologyISBN: 9780138242732Not the one you use?Change textbook
Chapter 13, Problem 26

Mr. Jake was admitted to the hospital with excruciating pain in his left shoulder and arm. He was found to have suffered a heart attack. Explain the phenomenon of referred pain as exhibited by Mr. Jake.

Verified step by step guidance
1
Understand that referred pain occurs when pain originating from one part of the body is perceived in another area, often due to shared neural pathways.
Recognize that the heart and the left shoulder/arm share common spinal segments for sensory input, specifically the thoracic spinal nerves (T1-T5).
Explain that during a heart attack, pain signals from the heart travel along these spinal nerves to the spinal cord.
Because the brain is more accustomed to receiving sensory input from the skin and muscles of the left shoulder and arm at these spinal levels, it misinterprets the heart pain as coming from those areas.
Conclude that this neural overlap causes Mr. Jake to feel pain in his left shoulder and arm, even though the actual source is the heart.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Referred Pain

Referred pain occurs when pain is perceived at a location other than the site of the painful stimulus. This happens because sensory nerves from different areas converge on the same spinal cord neurons, causing the brain to misinterpret the source of pain. In Mr. Jake's case, heart pain is felt in the left shoulder and arm.
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Visceral and Somatic Nerve Convergence

Visceral organs and somatic structures share common pathways in the spinal cord. Nerve fibers from the heart (visceral) and the left shoulder/arm (somatic) converge on the same spinal segments, leading to confusion in the brain about the pain's origin, which explains why heart pain is felt in the arm.
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Dermatomes and Pain Mapping

Dermatomes are skin areas supplied by specific spinal nerves. Understanding dermatomes helps explain referred pain patterns, as pain from internal organs is often felt in dermatomes linked to the same spinal segments. The left shoulder and arm dermatomes correspond to spinal segments that also receive heart sensory input.
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