During oesophagoscopy, a bolus is seen lodged above a benign ring. Repeated waves of peristalsis begin at the level of the obstruction and clear the residue, although the swallow that delivered the bolus has ended. These waves are called secondary peristalsis. Their key distinguishing feature is:

• A They are generated by pacemaker potentials from interstitial cells of Cajal in the stomach
• B They depend on cortical input relayed through the nucleus ambiguus
• C They occur only in the striated muscle portion of the oesophagus
• D They are initiated by local distension and do not require a pharyngeal swallow or voluntary initiation ✓

Explanation

Primary peristalsis is part of the coordinated swallow program. If it fails to clear the bolus, local distension of the oesophageal wall triggers secondary peristalsis through intrinsic myenteric circuits with vagal afferent-efferent support, without any new pharyngeal phase. The proximal striated muscle segment is not the site where this reflex operates.

Reference: Ganong's Review of Medical Physiology, 26th ed.

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Written and medically reviewed by the StethoPrep medical team.