The human brain is unique in its anatomy. The brain consists of billions of nerve cells that are interconnected in a complex way. Nevertheless, the brain can be easily divided into different parts and areas, some of which can be assigned specific functions. This article gives you an overview of the anatomy of the human brain.
Rough division of the brain into 5 parts
The human brain anatomy can be described in different ways. First, it is useful to consider the brain (encephalon) divided into five main regions. These five areas of the brain are recognizable to varying degrees in all vertebrates:
- end brain, often also called cerebrum (telencephalon)
- diencephalon
- midbrain (mesencephalon)
- hindbrain (metencephalon)
- hindbrain (myelencephalon, also: medulla oblongata)
The names of these main regions are based on the simple brain anatomy of lower vertebrates, in which the regions are arranged one behind the other in a tube-like manner. The human brain is more complex in comparison, but these five brain parts are still clearly recognizable despite further evolutionary development. To give you an idea of the human brain, we will take a closer look at the five brain regions mentioned below and describe other possible classifications within the brain anatomy.
The forebrain and diencephalon form the forebrain (prosencephalon)
The forebrain consists of the endbrain and the diencephalon. The large cortex of the endbrain (cerebral cortex, cortex cerebri) is particularly characteristic of the human brain anatomy. Its characteristic convolutions (gyri) and grooves (sulci) result in a significantly increased surface area, which means that the volume can remain relatively small.
The cerebrum is made up of two hemispheres that are separated from each other by the "fissura longitudinalis cerebri". Deeper inside, however, they are connected to each other by the so-called corpus callosum. In a frontal section of the brain, the gray and white matter of the hemispheres can be seen.
The picture "Brain Structure in Cross Section" represents the brain anatomy in such a section. The outer gray matter consists mainly of the cell bodies of the nerve cells and the inner white matter consists of the nerve fibers.
The 4 lobes of the forebrain
Both hemispheres can be divided into four lobes based on certain grooves:
- frontal lobe (lobus frontalis)
- parietal lobe (lobus parietalis)
- occipital lobe (lobus occipitalis)
- temporal lobe (lobus temporalis)
As the name suggests, the frontal lobe is located in the frontal area. The parietal lobe borders the frontal lobe from behind and extends to the occipital lobe at the back of the head. The temporal lobe is located laterally below the parietal lobe. The position of the brain lobes corresponds to the similarly named skull bones, as shown in the picture "skull bone anatomy" are shown.
Functional areas of the cortex
The human cerebral cortex is particularly highly developed. It is responsible for properties
responsible for making people what they are. Certain functions can be assigned to certain areas of the cortex. For example, there are areas in the temporal lobe that process information from the sense of hearing.The primary visual cortex, which is responsible for part of the visual information processing, is located in the occipital lobe.
The parietal lobe contains areas of body perception that mediate skin, organs, muscles and joints. The motor speech center and other motor areas are located in the frontal lobe. There are also areas there that are involved in personality formation.
The structure of the diencephalon
Between the hemispheres of the forebrain lies the diencephalon with the following structures:
- thalamus
- epithalamus with pineal gland
- hypothalamus with neurohypophysis
- subthalamus
The thalamus serves as a control center through which almost all information flowing to the cortex passes. It is also called the "gateway to consciousness". You can see the location of the thalamus in the image "Brain - Sagittal Section". This shows the brain anatomy in the sagittal section, i.e.
in the lateral view. The epithalamus, which sits on the thalamus, houses the pineal gland (epiphysis). This produces melatonin, known as the sleep hormone, and is thus involved in the sleep-wake rhythm.
The hypothalamus is located below the thalamus and is connected to the pituitary gland (hypophysis). The pituitary gland, which is responsible for hormonal control, is divided into the posterior lobe (neurohypophysis) and the anterior lobe (adenohypophysis). The adenohypophysis, which is made up of gland cells, is not part of the brain. The hypothalamus controls the autonomic nervous system, among other things, but is also involved in emotional life.
The limbic system consists of structures of the forebrain
The limbic system represents another functional division within the brain anatomy.
It includes brain structures that are responsible for controlling emotions. In addition, the limbic system has important functions in learning and is in contact with the hypothalamus. It surrounds the corpus callosum that connects the two hemispheres. The limbic system includes:
- structures of the olfactory bulb
- amygdala
- hippocampus
- cingulate gyrus
- parahippocampal gyrus
Due to the close relationship between the olfactory brain and the other structures of the limbic system, smells, memories and emotions are often linked. The amygdala plays a key role in the development of fear, while the hippocampus is important for learning processes and is involved in aggressive and motivational behavior.
The Anatomy of the Brainstem and Cerebellum
The midbrain, the pons of the hindbrain and the hindbrain form the brain stem (truncus cerebri). This is where the nuclei of the cranial nerves, fiber bundles of the hypothalamus and long pathways of nerve cells are located.
All three parts of the brain stem are connected to the cerebellum, which lies on top of the brain stem. The cerebellum is made up of the vermis (vermis cerebelli) and two hemispheres (hemispheria cerebelli). Together with the pons, it forms the hindbrain and is responsible for balance, the state of muscle tension and the coordination of muscle activity.
The brain stem finally merges with the hindbrain into the spinal cord, with the grey and white matter surrounding it. In terms of evolutionary history, the brain stem is the oldest part of the human brain anatomy.