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NBME 16 Answers

nbme16/Block 4/Question#39

A 32-year-old man begins to laugh while eating ...

While swallowing: closed; Immediately after laryngeal irritation: closed; while coughing: open

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submitted by zincy7(1),


WHILE SWALLOWING (see Laryngeal closure from Swallowing)

...true vocal fold closure that is the primary laryngopharyngeal protective mechanism to prevent aspiration during swallowing

  • Logic = Normal function; prevents food from going into trachea instead of esophagus. You dont want to aspirate food when you swallow, so you close your glottis and VCs

IMMEDIATELY AFTER IRRITATION (see Coughing - paragraph about the mechanism of the cough, step 3)

...The glottis closes (muscles innervated by recurrent laryngeal nerve) and the vocal cords contract to shut the larynx.

  • Logic = REFLEX to prevent aspiration of foreign body from going further into trachea.

WHILE COUGHING (see Coughing - paragraph about the mechanism of cough, step 5)

...The vocal cords relax and the glottis opens, releasing air at over 100 mph.

  • Logic = To help expel the foreign body out.


(From Swallowing Wiki)

Since the true vocal folds adduct during the swallow, a finite period of apnea (swallowing apnea) must necessarily take place with each swallow. When relating swallowing to respiration, it has been demonstrated that swallowing occurs most often during expiration, even at full expiration a fine air jet is expired probably to clear the upper larynx from food remnants or liquid. The clinical significance of this finding is that patients with a baseline of compromised lung function will, over a period of time, develop respiratory distress as a meal progresses

... The respiratory center of the medulla is directly inhibited by the swallowing center for the very brief time that it takes to swallow. This means that it is briefly impossible to breathe during this phase of swallowing and the moment where breathing is prevented is known as deglutition apnea.