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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.
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 metencephalon gives rise to the cerebellum and pons. The myelencephalon gives rise to the medulla oblongata. [71] Also during the fifth week, the brain divides into repeating segments called neuromeres. [65] [72] In the hindbrain these are known as rhombomeres. [73] A characteristic of the brain is the cortical folding known as gyrification.
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 medulla oblongata is responsible for several functions of the autonomic nervous system. These functions include: [ 7 ] 1) Respiration: monitors the acidity of the blood and sends electrical signals to intercostal muscle tissue to increase their contraction rate in order to oxygenate the blood as needed.
In some works (e.g. [9]), researchers have grouped the nuclei lineares into one nucleus, the nucleus linearis, shrinking the number of raphe to seven, e.g., NeuroNames makes the following ordering: [10] Raphe nuclei of medulla oblongata. Nucleus raphe obscurus; Nucleus raphe magnus; Nucleus raphe pallidus; Raphe nuclei of the pontine reticular ...
Most of them reach the surface by way of the anterior median fissure, and arch backward over the pyramid, the olive, and the lateral district of the medulla oblongata to enter the cerebellum through the inferior peduncle. The fibers are reinforced in their course by fibers emerging between the pyramid and olive.