QS Study

A diaphragm is a dome-shaped muscle forming the partition between the thoracic and abdominal cavities. It is the primary muscle used in respiration, which is the process of breathing. This dome-shaped muscle is located just below the lungs and heart.

Paralysis of the Diaphragm

A single dome of the diaphragm may be paralyzed by crushing or sectioning of the phrenic nerve in the neck. This may be necessary for the treatment of certain forms of lung tuberculosis when the physician wishes to rest the lower lobe of the lung on one side. It is the loss of control of one or both hemidiaphragms caused by a traumatic injury or disease process which decreases or terminates the impulse of respiratory stimuli originating in the brain. Occasionally, the contribution from the fifth cervical spinal nerve joins the phrenic nerve late as a branch from the nerve to the subclavius muscle. This is known as the accessory phrenic nerve. To obtain complete paralysis under these circumstances, the nerve to the subclavius muscle must also be sectioned. Whether the paralysis occurs in one (unilateral) or both (bilateral) sides of the diaphragm, all patients will experience some amount of reduction in lung capacity.

Penetrating Injuries of the Diaphragm

Penetrating injuries can result from stab or bullet wounds to the chest or abdomen. Any penetrating wound to the chest below the level of the nipples should be suspected of causing damage to the diaphragm until proved otherwise. This specific injury is seen commonly where penetrating trauma is prevalent. The arching domes of the diaphragm can reach the level of the fifth rib (the right dome can reach a higher level). This occurs most often from gunshot wounds but can result from knife wounds.

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