Brainstem

Abstract

Abstract The brainstem, responsible for many primitive reflexes, is composed of the midbrain, the pons, and the medulla, each of which performs critical roles in homeostasis. This chapter examines the anatomy and function of each region, as well as reviewing the brainstem’s role in postoperative nausea and emesis. Postoperative nausea and vomiting are, in part, related to the chemoreceptor trigger zone, located within the medullary area postrema; this area and the nucleus tractus solitarius of the medulla constitute the most significant components of the vomiting center. Emetogenic substances activate receptors within the chemoreceptor trigger zone, and this signal is conducted to the nucleus tractus solitarius, which activates the vomiting reflex.