Brainstem: What It Is, Functions And Parts

The brainstem is a structure of the central nervous system that contains afferent and efferent neural circuits, that is, they receive and send motor, vegetative and sensory information.

If you’re wondering where the brain stem is located, specifically, it is located in the most caudal part of the brain that is to say, between the brain and spinal cord If we want to see it in its entirety, we will not be able to do it with the naked eye in a normal brain, since the cerebral cortex hides a large part of the brain stem and the midbrain is practically not visible. To better understand its location, you can consult this article about the cerebral cortex: functions and parts.

The general function of the brain stem is collect and send information both sensory and motor, head and face , unlike the spinal cord, which transmits and receives information from the trunk and extremities. Specifically, the functions of the brain stem are:

• Collects and sends sensory information from head and face.
• Receives information from the brain and distributes it to the motor and vegetative periphery of the head and face
• Organize reflex responses of head and face.
• Control of cortical activation : is related to the nuclei of the reticular formation.
• Controls the acceptance or rejection of sweet or bitter foods,
• Modulates satiety or physiological hunger signals such as a decrease in glucose metabolism or having food in the digestive system.

If you are interested in learning more about other parts of the brain and how it works, in this article you will find more information about how the human brain works.

The brain stem is made up of three main elements: the medulla oblongata (medulla oblongata), the pons and midbrain In these three parts of the brainstem we find the main structures that compose it, which are divided between those found on its ventral side and those found on the dorsal side.

ventral face

On the ventral side of the brainstem you can see the different structures. On the one hand, on the ventral side of the midbrain there are the cerebral peduncles, structures that at first glance could appear to be two slightly inclined columns formed by axons, which conduct motor information through them.

On the other hand, in the central part of the pons and the medulla oblongata, specifically in the latter, there are the pyramids and the bulbar olives:

• Pyramids : they are made up of axons that cross, many of them, the midline, giving rise to what is called pyramid accusation, that is, that place where the parts of the axons that form the pyramids cross the midline and where the information is stored. lateralizes
• bulbar olives : They are related to the processing of auditory information.

If you want more information about how these structures work, we recommend this article about the medulla oblongata: what it is, parts, characteristics and functions.

Dorsal side

Most of the dorsal aspect of the brainstem is hidden by the cerebrum. Even so, we also find some relevant structures such as colliculi or quadrigeminal tubercles :

• Two superior colliculi : they are related to the processing of optical sensory information.
• Two inferior colliculi or quadrigeminal tubercles : they are related to the processing of auditory sensory information.

To locate ourselves in the brain stem and mention where certain alterations or structures are found, we use more specific terminology instead of talking about the dorsal or ventral side. Specifically, we talk about tectum to refer to the dorsal part and tegmentum to refer to the ventral part.

Cranial nerves

On the surface of the brain stem we can see 10 of the 12 cranial nerves related to sensory and motor information from the head and face. The other two pairs of cranial nerves (I and II) do not connect with the brain stem, but rather connect with their respective sensory structures directly, and are the olfactory nerve and the optic nerve, connected to the optic chiasm.

Unlike spinal nerves which are all mixed, that is, they conduct both sensory and motor information, cranial nerves can be sensory only, motor only, or mixed. Let’s see which are the 10 pairs of cranial nerves connected to the brain stem:

• III. oculomotor nerve : is related to the movements of the eyeball.
• IV: Trochlear or pathetic nerve : It is also related to the movements of the eyeball.
• V. Trigeminal nerve : It is a mixed nerve, so it receives and transmits sensory and motor information. The sensory branch carries somatosensory and face information, and the motor branch carries jaw movements.
• SAW. Abduct us : like the third and fourth pair, it is related to the transport of information from eye movements.
• VII. Facial : another mixed nerve that receives and transmits sensory and motor information. Motor information is related to facial gestures and lacrimal and salivary glands. On the other hand, the sensory branch is related to the taste of the anterior 2/3 of the tongue.
• VIII. cochlear vestibule
• IV. Golosso-pharyngi : mixed nerve, whose vegetative part is responsible for functions such as swallowing, and the sensory part of taste of the posterior third of the tongue and pharynx.
• X. Vagus or lazy : carries vegetative information that innervates the digestive, respiratory and cardiac systems, among others. In addition, it also transmits taste sensory information to the pharynx.
• XI. accessory spinal cord : motor nerve related to information about neck movements.
• XII. Halibut : motor nerve related to tongue movements.

This article is merely informative, at PsychologyFor we do not have the power to make a diagnosis or recommend a treatment. We invite you to go to a psychologist to treat your particular case.

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