Case

A 38 year old patient is admitted to the hospital after a gunshot wound to the right chest. The patient is awake and talking with bilateral and equal breath sounds and heart sounds. A chest X-ray shows that there are no fractures and no major internal bleeding. There is, however, muscle weakness in both pectoralis major and pectoralis minor.

Question 1/2 - What do you think is causing the weakness?

Click on your selected option(s) below  (correct = 2, possible 3, over-thinking = 4+)

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Incorrect.  Muscular strain is usually from an over-extension, over-use, or unusual stretch trajectory. A bullet in isolation won't cause a muscle strain.

Correct! A patient will be reluctant to contract an injured muscle and stronger contractions would cause stronger pain. Thus, underutilization to avoid pain is very possible. 

Correct!  If the pectoral nerves were injured by the bullet then there would be reduced neural input to the muscle and reduced strength of contraction.

Incorrect. Complete transection of a nerve would remove all function of that muscle, weakness indicates some nerve fibers are intact.

Possible, but unlikely in this case. For muscle weakness to be the result of insufficient blood reaching the muscle (and thus insufficient oxygen/energy), there would be significant hemorrhage from the broken vessels. The chest X-Ray indicates there to be no major bleeding.