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Myelencephalon (Medulla)

Breathing, heart rate, blood pressure, peristaltic action (digestive movements), other reflex movements Between the metencephalon and the spinal cord lies this basic unit common to all vertebrates. The life-supporting medulla regulates breathing, heart rate, blood pressure, and digestive movements, and it governs reflexes: vomiting, sneezing, coughing, and swallowing. Sleeping people often breathe with characteristic regularity. This is medulla breathing—without modulation of will. Some who have been sleep paralyzed have experienced this form of breathing consciously. Sleep paralysis is a condition wherein one wakes up paralyzed—temporar- ily locked in. One’s lungs inflate and deflate but without the possibility of willful modulation. Paralyzed, one may be terrified with a racing heart, struggling not only to move but also to get more oxygen. Yet the medulla dictates the inflation-deflation cycle—there is nothing to do about it. After a minute or two, the person typically regains control as if nothing had happened.

Myelencephalon Pathologies

Lateral medullary syndrome (Wallenberg’s syndrome) Patients with this syndrome lose the ability to feel pain and temperature on one side of the body, have poor coordination, exhibit hoarseness, loss of the gag reflex, and difficulty with speech and swallowing.

Medial medullary syndrome This syndrome manifests as loss of proprioceptive, touch-sensing, and pressure-sensing abilities on one side of the body, and partial upper body paralysis on one side of the body.

Dorsal medullary syndrome Patients with this syndrome exhibit involuntary eye movements, vertigo, and vomiting.

Myelencephalon Summary

The medulla evolved early with basic life support systems. Damage here can be life threatening. It is also important for correct functioning of many sensorimotor functions.

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