brainstem

American  

[brayn-stem] / ˈbreɪnˌstɛm /

Or brain stem

noun

1. the portion of the brain that is continuous with the spinal cord and comprises the medulla oblongata, pons, midbrain, and parts of the hypothalamus, functioning in the control of reflexes and such essential internal mechanisms as respiration and heartbeat.

---

brainstem British  

/ ˈbreɪnˌstɛm /

noun

1. the stalklike part of the brain consisting of the medulla oblongata, the midbrain, and the pons Varolii

---

brainstem Scientific  

/ brān′stĕm′ /

1. The part of the vertebrate brain located at the base of the brain and made up of the medulla oblongata, pons, and midbrain. The brainstem controls and regulates vital body functions, including respiration, heart rate, and blood pressure.

2. See also reticular formation

---

Etymology

Origin of brainstem

First recorded in 1875–80; brain + stem ¹

Example Sentences

See Examples For:

brainstem

The researchers also examined the locus coeruleus, a tiny area deep within the brainstem that is roughly the size of a grain of rice.

From Science Daily ● Aug. 29, 2026

The brainstem occupies only a sliver of the brain, yet it keeps people alive.

From BBC ● Jul. 13, 2026

That, says Mitra, has made it possible to chart the human brainstem at an unprecedented scale.

From BBC ● Jul. 13, 2026

The mice performed the task successfully until researchers temporarily switched off the brainstem neurons.

From Science Daily ● Jun. 24, 2026

Deep inside is the oldest part, the brainstem, which conducts the basic biological functions, including the rhythms of life—heartbeat and respiration.

From "Cosmos" by Carl Sagan