Medulla Oblongata: Structure And Functions

The medulla oblongata or medulla oblongata is a subcortical structure that is located in the lower part of the brainstem. In it you can find nerve connections that carry out sensory and motor functions. Now, what exactly does it take care of? What is its importance?

Through this article we will solve these questions and explain some curious facts about this structure of our brain that is so important for our survival.

Structure of the medulla oblongata

The medulla oblongata is the most caudal structure of the brain stem. Its shape is similar to that of a cone and connects the brain with the spinal cord. However, both at the level of composition and function it is not homogeneous. In addition, it is made up of different nuclei, in which there are very relevant structures such as the following:

• Bulbar pyramids. They are found in the ground of the bulb and in them stand out the bundles of nerve fibers that connect the bulb with the cortex and the spine. It is here where the pyramidal decussation occurs -especially the motor pathways-, that is, there is a crossing of the nerve fibers from one side to the other. This explains why the cerebral cortex is in charge of controlling movements on the opposite side of the body.
• Lower cerebellar peduncles. They are located in the posterolateral area. They connect the cerebellum with the upper part of the medulla oblongata. Nerve fibers pass through them.
• Lemnisci. These are bundles of nerve fibers that transmit information between the brain and the spinal cord. The lemniscal fiber bundles also decuse, but carrying sensory information.
  • Medial lemniscus: it is an elongated, thin and highly myelinated structure, which is found on each side of the median line of the medulla oblongata. It carries information originating from the graceful and wedge-shaped nuclei. It is located behind the cerebrospinal fibers and between the olives.
  • Medial longitudinal fasciculus: it is a region that is located next to each medial lemniscus. It has numerous ascending and descending fibers. Its function is vital for head position changes and for coordination of eye movements.

• Olive complex. It is located in the brainstem, part in the pons and part in the medulla oblongata. It is a set of oval-shaped nuclei, similar to an olive. They regulate voluntary muscle movements.

Nuclei of the medulla oblongata

Nuclei consist of clearly differentiated masses of neurons. Let’s see some of them:

• Trigeminal nucleus. It is responsible for transmitting information related to pain, temperature and touch.
• Dorsal nucleus of the vagus. It goes through the vagus nerve, hence its name. These are neural networks that control the enteric nervous system.
• Ambiguous nucleus. The nerves belong to and start in this nucleus: vagus, accessory and glossopharyngeal, which are in charge of the muscles of the pharynx and larynx.
• Nucleus of the solitary tract. It is responsible for the control of visceral sensitivity. In addition, it participates in the taste perception.

Functions of the medulla oblongata

The medulla oblongata is involved in various functions, which are vital to the body. In fact, the destruction of this structure or the cessation of its functioning leads to death. Let’s see:

Autonomous function control

The medulla oblongata is responsible for the control of the involuntary functions of the viscera and the maintenance of homeostasis. For instance:

• Cardiovascular system. It is responsible for maintaining blood pressure and in addition to regulating the heart rate and maintaining vasoconstriction.
• Breathing. The medulla oblongata is responsible for regulating it, that is, it manages respiratory function.
• Digestion. Manage the involuntary muscles that are involved in this process. It also regulates the secretion of digestive juices and participates in swallowing processes.

In addition, the medulla oblongata manages other involuntary actions:

• Cough.
• Threw up.
• Sneeze.

Sensory control

The medulla oblongata is also responsible for the transfer of sensory information between the peripheral system and the central nervous system. To do this, it connects the two systems and sends information to the thalamus that is later communicated to the rest of the brain.

Problems associated with the medulla oblongata

In the bulb there are some cranial nerves (IX, X, XI, XII), their damage causes problems in the regions and functions that they control:

• Glossopharyngeal or cranial nerve IX. It collects the taste information and the sensitive information from the pharynx. It makes swallowing easier by coordinating various muscles in the neck. In addition, it transmits signals to the salivary gland.

• Vagus nerve or cranial nerve X. It is also known as pneumogastric. It innervates the pharynx, esophagus, trachea, bronchi, heart, stomach, and liver. That is, it regulates our autonomous system.
• Accessory nerve or cranial nerve XI. It is also known as spinal. It is in charge of the cephalo-gyro movement. Therefore, it intervenes in movements of the head, neck and shoulders.
• Hypoglossal nerve or cranial nerve XII. It intervenes in the muscles of the tongue and in the action of swallowing.

If one of them fails, you could experience trouble swallowing and even moving around. Thus, when this structure of our body does not work properly, the following could be experienced:

• Difficulty or paralysis of movement.
• Respiratory and heart problems
• Vertigo.
• Difficulty to swallow.
• Loss of consciousness
• Soft spot.
• Lethargy
• Visual and hearing problems.

As we can see,  the medulla oblongata is so important that without it we would be risking our survival. Although it is approximately 3 centimeters long and two centimeters wide, we cannot underestimate it.