Brain surface: Journeys to the brain-2

Brain surface map

Brain surface regions

Image courtesy: S Bhimji MD; from Neuroanatomy, Postcentral Gyrus Copyright © 2020, StatPearls Publishing LLC.

under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/),

We began this series with the journey to the brain covers.

This post journeys on the brain surface. The brain surface is full of ridges (bumps) and valleys (grooves) (see Figure 1). Experts have given specific names to recognize these bumps and grooves. Moreover, in the medical field, the bumps are named gyri (its singular word is gyrus) and grooves as sulci (its singular word is sulcus).

The purpose of these ridges and valleys is to increase their surface area. As a result, the surface areas that are assigned to specific jobs have enough space for their work.

This figure shows the lateral view of the brain and the major lobes are labeled.

Figure 1: Brain surface:

Source: openstax.org, RICE University
under the CC BY 4.0 license

Naming the brain regions

Experts have categorized the brain surface into four different regions; they call it lobes: Frontal lobe, parietal lobe, temporal lobe, and occipital lobe. This naming depends on the region placed within the skull. Interestingly, each lobe carries out distinct jobs. Figure 1 shows those four lobes on the left half of the brain. Similarly, we have the same mirror lobes on the right side too.

Demarcations of the lobes

As shown in Figure 2, the Central groove (Sulcus) separates the Frontal lobe from the Parietal lobe. Moreover, another groove that sits between the Parietal lobe and the Occipital lobe separates those two lobes. Similarly, a large groove which is called the Lateral fissure separates the Parietal lobe from the Temporal lobe.

Brain regions (lobes) in detail:

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Figure 2: Brain surface regions: Source: (Image courtesy: S Bhimji MD; from Neuroanatomy, Postcentral Gyrus Copyright © 2020, StatPearls Publishing LLC. under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/),

Frontal lobe

With Figure 2, I am starting my walk from the front end of the Frontal lobe. When I climb to the top, I meet the Central groove (sulcus). The Frontal lobe ends there.

We – humans – own the largest Frontal lobe proportionate to the body size among all animals. This lobe carries out jobs that no other animal can do: higher jobs such as thinking, speaking, and decision-making jobs. However, every single area of this lobe is specialized for one job. If something happens to this area, we lose that function. For example, if a stroke attack prevents blood supply to Broca’s area, which is specialized in speech production, we lose speech.

Parietal lobe

As soon as I jump over the Central groove from the Frontal lobe’s edge to the other side, I land on the Parietal lobe. It lays behind the Frontal lob. The Parietal lobe extends back until it meets the next lobe – The occipital lobe.

We see the upper-left side view of the left Parietal lobe in Figure 2. The parietal lobe reads messages related to taste, touch, and temperature and controls our balance while standing and walking. This simply means if this area inflicts any damage, we will not be able to taste, feel touch, or temperature and will fall.

Temporal lobe

Now, walk with me over to the brain’s left side to meet another larger groove, called Lateral Fissure.

Once I cross over this fissure, I lands on to the Temporal lobe. The part above is the side view of the left Frontal lobe.

The Temporal lobe’s main job is to understand and interpret the language. 

Occipital  Lobe

Behind the parietal and Temporal lobes, we find the Occipital lobe. This lobe spreads over the back of the brain. Without this area, we cannot see, recognize, and interpret anything although we have eyes.

In our next journey, we will meet the “two little humanoids” who live on our brain surface.

Author: Prasantha De Silva

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