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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 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.
Beginning in the sympathetic nervous system, an external stimulus affects the adrenal medulla and causes a release of catecholamines. The sympathoadrenal system is a physiological connection between the sympathetic nervous system and the adrenal medulla and is crucial in an organism's physiological response to outside stimuli. [1]
The adrenal medulla is the principal site of the conversion of the amino acid tyrosine into the catecholamines; epinephrine, norepinephrine, and dopamine. Because the ANS, specifically the sympathetic division, exerts direct control over the chromaffin cells , the hormone release can occur rather quickly. [ 2 ]
The respiratory center is divided into three major groups, two in the medulla and one in the pons. The two groups in the medulla are the dorsal respiratory group and the ventral respiratory group. In the pons, the pontine respiratory group is made up of two areas – the pneumotaxic center and the apneustic center. The dorsal and ventral ...
The ventral portion of the medulla oblongata contains the medullary pyramids. These two ridge-like structures travel along the length of the medulla oblongata and are bordered medially by the anterior median fissure. They each have an anterolateral sulcus along their lateral borders, where the hypoglossal nerve emerges from.
In the medulla oblongata, the arcuate nucleus is a group of neurons located on the anterior surface of the medullary pyramids. These nuclei are the extension of the pontine nuclei. [1] They receive afferents from the corticospinal tract. [citation needed] They in turn project efferents into the cerebellum through the inferior cerebellar ...
The lateral corticospinal tract neurons cross the midline at the level of the medulla oblongata, and controls the limbs and digits. [1] [3] The lateral tract forms about 90% of connections in the corticospinal tract; [2] the vast majority cross over in the medulla, while the rest (about 2-3%) remain ipsilateral. The anterior corticospinal tract ...