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The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. [1] It is anterior and partially inferior to the cerebellum . It is a cone-shaped neuronal mass responsible for autonomic (involuntary) functions, ranging from vomiting to sneezing . [ 2 ]
The cardiovascular centre, or cardiovascular center, is part of the medulla oblongata of the brainstem. [1] [2] Normally, the heart beats without nervous control. In some situations, such as exercise, and major trauma, the cardiovascular centre is responsible for altering heart rate. It also mediates respiratory sinus arrhythmia.
The vasomotor center (VMC) is a portion of the medulla oblongata.Together with the cardiovascular center and respiratory center, it regulates blood pressure. [1] It also has a more minor role in other homeostatic processes.
A disrupted blood supply to posterior inferior cerebellar artery due to a thrombus or embolus can result in a stroke and lead to lateral medullary syndrome. Severe occlusion of this artery or to vertebral arteries could lead to Horner's Syndrome as well.
The system relies on specialized neurons, known as baroreceptors, chiefly in the aortic arch and carotid sinuses, to monitor changes in blood pressure and relay them to the medulla oblongata. Baroreceptors are stretch receptors and respond to the pressure induced stretching of the blood vessel in which they are found.
The medulla oblongata, often just referred to as the medulla, is the lower half of the brainstem continuous with the spinal cord. Its upper part is continuous with the pons. [11]: 1121 The medulla contains the cardiac, dorsal and ventral respiratory groups, and vasomotor centres, dealing with heart rate, breathing and blood pressure.
The aortic bodies give feedback to the medulla oblongata, specifically to the dorsal respiratory group, via the afferent branches of the vagus nerve (cranial nerve X). [1] [3] The medulla oblongata, in turn, regulates breathing and blood pressure.
The Bainbridge reflex (or Bainbridge effect or atrial reflex) is a cardiovascular reflex causing an increase in heart rate in response to increased stretching of the wall of the right atrium and/or the inferior vena cava as a result of increased venous filling (i.e., increased preload).