The medulla connects to the spinal cord ,which is long piece of nerve tissues running down from the brain through the backbone.It is surrounded by the vertebral column,which provides safety to the spinal cord .The spinal cord comprises multiple nerves that collectively from the nervous system.
CONTINUED FROM ABOVE... As the brain stem ascends from the spinal cord, it widens and becomes more complex in its structures, both internally and externally.
The exterior of the brain stem consists of white matter that conducts nerve signals within the brain stem and to the spinal cord and other regions of the brain. Masses of gray matter, known as nuclei, perform the processing role of the brain stem. The reticular formation, a network of mixed gray and white matter, extends throughout the interior of the brain stem and plays an important role in stimulation of the cerebrum and the muscles of the body.
Three major regions make up the brain stem: medulla oblongata, pons, and midbrain.
The medulla is the inferior-most region of the brain stem that connects the brain to the spinal cord. It is a tube very similar structurally to the spinal cord, but is wider and contains several masses of gray matter internally.
Superior to the medulla is the pons, which is larger and structurally more complex than the medulla.
Finally, the midbrain forms the most superior and most complex region of the brain stem.
Physiology
The brain stem, through its gray matter, provides many of the basic survival and reflex functions for the body. Through its white matter, the brain stem forms the connections between the brain and the body via the spinal cord, including:
The corticospinal tract for motor signals
The posterior column-medial lemniscus pathway for senses including proprioception and fine touch
The spinothalamic tract for pain, itch, and other signals.
Ten of the brain’s twelve cranial nerves also originate in the brain stem, providing vital connections between the brain and the sensory organs, heart, and digestive organs.
The reticular formation, which extends throughout the brain stem, performs several important functions, including the stimulation of the cerebral cortex and the production of muscle tone. Stimulation of the cerebral cortex by the reticular formation produces the effect of being awake and conscious, while the inactivation of the reticular formation leads to sleep.
The medulla contains all of the neurons that connect the brain to the spinal cord, and it is at the level of the medulla that about 90% of these neurons switch from the left side of the body to the right and vice versa. Although the reason for this switch is unknown, it explains why the brain feels and controls the contralateral side of the body. These neurons passing through the medulla also form many relays, where one neuron passes its signal on to another neuron that continues onward to the brain or body. Nuclei of gray matter in the medulla include the cardiovascular center, which controls the heart rate and blood pressure, and the medullary rhythmicity area, which controls the breathing rate. Many vital survival reflexes are integrated in the medulla, including those for swallowing, vomiting, and coughing.
Like the medulla, the pons plays a vital role in communication as it contains all of the neurons that connect the higher regions of the brain to the medulla and spinal cord. The pons also acts as a bridge in a couple crucial ways:
It connect the left and right hemispheres of the cerebellum to one another
It connects the cerebellum to the other regions of the brain.
Several nuclei in the pons work with the medullary rhythmicity center to control breathing, while other nuclei form the roots of several cranial nerves.