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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 ]
Each cerebellar inferior peduncle connects the spinal cord and medulla oblongata with the cerebellum, and comprises the juxtarestiform body and restiform body. Important fibers running through the inferior cerebellar peduncle include the dorsal spinocerebellar tract and axons from the inferior olivary nucleus , among others.
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.
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.
Section of the medulla oblongata at the level of the decussation of the pyramids. Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' , from Latin decem 'ten' and as 'as'). In Latin anatomical terms, the form decussatio is used, e.g. decussatio pyramidum.
Each olivary body is located on the anterior surface of the medulla lateral to the pyramid, from which it is separated by the antero-lateral sulcus and the fibers of the hypoglossal nerve. Behind ( dorsally ), it is separated from the postero-lateral sulcus by the ventral spinocerebellar fasciculus .
The cerebellorubral fibers cross over at this point to enter the contralateral red nucleus. The dentatothalamic fibers also cross over and ascend to synapse in the ventral intermediate, and ventral anterior nuclei of the thalamus. The fastigioreticular fibers enter the reticular formation of the midbrain, pons, and medulla oblongata.
The lateral corticospinal tract is a descending motor pathway that begins in the cerebral cortex, decussates in the pyramids of the lower medulla [1] (also known as the medulla oblongata or the cervicomedullary junction, which is the most posterior division of the brain [2]) and proceeds down the contralateral side of the spinal cord.