Question

Demonstrating Referred Pain

You’ll need a small plastic bin (approximately 1 quart volume or large enough to place your elbow into it), water, and ice cubes to conduct this lab.

Referred pain is a sensory experience in which pain is perceived as arising in one area of the body when in fact another, often quite remote area is receiving the painful stimulus. Thus the pain is said to be “referred” to a different area. Many of us have experienced referred pain as a radiating pain in the forehead after quickly swallowing an ice-cold drink. Referred pain is important in many types of clinical diagnosis because damage to many visceral organs results in this phenomenon. For example, inadequate oxygenation of the heart muscle often results in pain being referred to the chest wall and left shoulder (angina pectoris), and the reflux of gastric juice into the esophagus causes a sensation of intense discomfort in the thorax referred to as heartburn.

The phenomenon of referred pain is easily demonstrated in the laboratory. You’ll want to conduct the following experiment on a counter near a sink.

Fill the plastic container about one third full of water from the tap. Add about 15 ice cubes to the water in the bin. Allow the ice water to sit for about 2-3 minutes before using.

Immerse your elbow in the ice water allowing your elbow to touch the bottom of the plastic bin. Relax your hand and arm muscles somewhat. Note what you feel upon immersion in the water. Leave your elbow in the water for 1-2 minutes, depending on your comfort level (there will be some discomfort involved in this experiment). 2 minutes is best. Has the “pain” that began in your elbow moved?   After 2 minutes of immersion, remove your elbow from the ice water. Wait 3 more minutes and then make your last recording in the table.

Referred Pain: Record your results in this table.

Time of observation	Your sensory experience (include localization of pain)
on immersion
after 1-2 minutes
3 minutes after removal

Please answer the following questions:

1. The ulnar nerve, which serves the medial third of the hand, is involved in the phenomenon of referred pain experienced during your test. How does the localization of this referred pain correspond to the areas served by the ulnar nerve?

2. Where would referred pain appear if the following organs were receiving painful stimuli?

(see figure in Chapter 13 of your textbook for help).

Lungs and Diaphragm –

Appendix –

Heart –

Answer 1

1. Referred pain can be defined as the pain experienced at a site on the body apart from the area that is diectly affected. This is due to the presence of a vast network of nerve fibres that are present in our body. These interconnection of nerves causes pain at the sites other than the ones directly affected.

Ulnar nerve is one of the three main nerves in our arms. It ranges from the neck to the hand, specifically the third and the fourth finger. It also passes through the elbow. Hence, sensations exprerienced at the elbow might also travel to the regions connected to it such as the neck or the hand which is very commonly observed.

2. Painful sensations observed at the lungs and diaphragm can cause referred pain at one side of the neck , shoulder or sometimes the whole upper body.

Pain at the appendix can cause referred pain at the lower abdomen region or the id-gut region.

Painful stimulus at the heart can cause referred pain in the left arm, upper and the middle region of the back and the chest region.