Lobes of the Brain: Cerebral Cortex Anatomy & Function
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Introduction
We will discuss the cerebrum, cerebral cortex layer, and the different lobes of the brain along with their function, anatomy, and physiology in this post!
The cerebrum is located superior/anterior to the cerebellum and brainstem, and the cerebrum by definition functions to integrate sensory stimuli, motor information, and carry out executive functions.
The cerebral cortex has 4 main lobes - frontal lobe, parietal lobe, occipital lobe, and temporal lobe - and their location, function, and anatomy all differ.
All together the brain contains 6 lobes, the 4 main ones mentioned, plus the insular and limbic lobes.
We will use labeled diagrams and lateral images of the brain (side views) to walk through each lobe of the cerebrum.
Every EZmed post is filled with simple tricks to remember the content, and today is no different as you will learn a useful way to recall the main functions of each lobe!
Let’s get started!
Brain Anatomy
The central nervous system is made up of the brain and spinal cord.
The main components of the brain are the cerebrum, cerebellum, and brainstem.
We will focus on the cerebrum, the largest part of the brain, in this post.
The cerebrum is divided into 2 hemispheres (right and left) by a deep groove known as the longitudinal fissure.
The 2 cerebral hemispheres are connected by the corpus callosum, allowing them to communicate and send information to one another.
The cerebrum has many different functions including memory, cognition, language, thought, judgement, reasoning, problem solving, decision making, attention, motor control, and sensory processing.
We will be revisiting these functions as we walk through each lobe of the cerebral cortex below.
In order to make the many advanced cognitive functions of the cerebrum possible, folds are formed in the cerebral cortex to increase its surface area within the cranium (skull) - a process known as gyrification.
This process creates a larger cortical surface area within a smaller space, and greater cognitive functionality is possible as a result.
The folded structure of the cerebral cortex has peaks called gyri (singular gyrus) and grooves called sulci (singular sulcus).
Some of the gyri and sulci are anatomically and/or functionally important as we will see below.
Image: The main components of the brain are the cerebrum (colored), cerebellum, and brainstem. The longitudinal fissure divides the cerebrum into 2 hemisphere (right and left) which are connected by the corpus callosum. Cerebral functions include executive functioning, motor control, and sensory processing. The cerebral cortex has a folded structure with peaks (gyri) and grooves (sulci).
Cerebral Cortex
So what exactly is the cerebral cortex, and what are the different lobes that make it up?
The cerebrum has an outer layer of grey matter, known as the cerebral cortex, which surrounds the inner layer of white matter.
The cerebral cortex can be divided into 4 main lobes: frontal, parietal, occipital, and temporal.
The names of the lobes correlate with the cranial bones that overlie them.
Each lobe comprises specific cortical areas that carry out the one or two primary functions of that lobe.
You will learn a trick at the end to remember what these main functions are.
But first, let’s discuss each lobe and their cortical areas starting with the frontal lobe.
Image: The cerebrum is made up of an outer layer of grey matter, known as the cerebral cortex, which surrounds the inner white matter layer. The cerebral cortex has 4 main lobes: frontal, parietal, occipital, and temporal.
Frontal Lobe
The frontal lobe is the largest lobe in the cerebral cortex and is located in the front of the brain as the name suggests.
Boundaries
There are 2 boundaries that separate the frontal lobe from the adjacent parietal and temporal lobes.
Central Sulcus - Frontal and Parietal
Lateral Sulcus (Sylvian Fissure) - Frontal and Temporal
First, the central sulcus is the groove that divides the frontal lobe and parietal lobe.
Second, the lateral sulcus (also known as the Sylvian fissure) separates the frontal lobe from the temporal lobe.
Image: The central sulcus divides the frontal lobe (blue) and parietal lobe (yellow). The lateral sulcus (Sylvian fissure) separates the frontal lobe (blue) from the temporal lobe (green).
Frontal Lobe Function = “Action”
While the frontal lobe has many different roles, the overall function can be remembered by the word “Action”.
This will include both mental and physical actions.
So what exactly does this mean?
Mental Actions
Starting with “mental actions”, the frontal lobe is in charge of executive functions such as problem solving, planning, judgement, motivation, social behavior, decision making, impulse control, personality, memory, learning, reward, and attention.
Many of these functions are mediated by the neurotransmitter dopamine.
Image: The frontal lobe (blue) is involved in “mental actions” or executive functions such as problem solving, decision making, planning, behavior, etc.
Physical Actions
In addition to “mental actions”, the frontal lobe is also involved in “physical actions” including the planning, control, and execution of voluntary muscle movements.
Image: The frontal lobe (blue) is involved in “physical actions” or voluntary motor movements.
Functional Cortical Areas - Frontal Lobe
There are specific cortical areas within the frontal lobe responsible for these executive functions (mental actions) and voluntary motor movements (physical actions).
We are going to focus on 5 main cortical areas:
Primary Motor Cortex
Motor Association Cortex
Frontal Eye Field
Prefrontal Cortex
Broca’s Area
Let’s walk through each one using the central sulcus as our starting point.
1. Primary Motor Cortex
Just anterior to the central sulcus is a gyrus called the precentral gyrus, and it is the site of the functional area known as the primary motor cortex.
The role of the primary motor cortex is to initiate and execute voluntary muscle movements.
The primary motor cortex sends motor information down through the spinal cord and out to skeletal muscles to tell them to move.
The body can be mapped out on the primary motor cortex as depicted below.
The map shows the specific cortical areas that control certain body parts.
Generally speaking as you travel from the medial aspect of the primary motor cortex to the lateral aspect, you will travel from the lower extremities to the upper body.
For example, the medial aspect of the primary motor cortex controls voluntary movements to the lower extremities, and the lateral aspect of the primary motor cortex controls voluntary movements to the upper extremities and face.
Furthermore, the left primary motor cortex (left hemisphere) will control most of the movements to the right side of the body, and the right primary motor cortex (right hemisphere) will control most of the movements to the left side of the body.
Image: The primary motor cortex (red) is located anterior to the central sulcus on the precentral gyrus, and it is involved in voluntary muscle movement. The medial aspect of the premotor cortex controls motor movements to the lower extremities, whereas the lateral aspect controls motor movements to the upper extremities and face.
2. Motor Association Cortex (Premotor Cortex/Supplementary Motor Cortex)
Anterior to the primary motor cortex is a functional area called the motor association cortex.
The common theme you will see among all the lobes is that each primary cortex has an association cortex.
The motor association cortex is made up of the premotor cortex and the supplementary motor cortex.
The function of the motor association cortex is to plan and coordinate movements, whereas the primary motor cortex is more involved in actually executing the movement itself.
Image: The motor association cortex (purple) is made up of the premotor cortex and supplementary motor cortex. It is located anterior to the primary motor cortex (red) and is involved in the planning and coordination of voluntary motor movements.
3. Frontal Eye Field
The next functional area is the frontal eye field, and it is involved in the planning, control, and execution of eye movements.
Image: The frontal eye field (green) is involved in the planning, coordination, and execution of eye movements, especially rapid ones.
4. Prefrontal Cortex
So far we have mainly focused on the “physical” motor actions of the frontal lobe, and we have not discussed the “mental” executive actions.
This is where the prefrontal cortex comes into play.
The prefrontal cortex is located in the anterior frontal lobe.
It is involved in memory, behavior, and executive functions such as decision-making, judgement, problem solving, planning, etc.
Image: The prefrontal cortex (blue) is involved in executive functioning, behavior, and personality.
5. Broca’s Area
The last main functional area of the frontal lobe we will discuss is Broca’s area.
Broca’s area is usually located in the dominant hemisphere, so for most people this will be the left hemisphere since they are right-handed.
Broca’s area stimulates the muscles that help us produce speech and form words.
Image: Broca’s area (orange) is usually located in the dominant hemisphere. It is involved in the production of speech and formation of words.
Parietal Lobe
The next 3 lobes are involved in sensory functions rather than motor ones.
We will start with the parietal lobe which is located posterior to the frontal lobe.
Boundaries
There are 3 boundaries that separate the parietal lobe from the adjacent frontal, temporal, and occipital lobes.
Central Sulcus - Parietal and Frontal
Lateral Sulcus (Sylvian Fissure) - Parietal and Temporal
Parieto-Occipital Sulcus - Parietal and Occipital
First, the central sulcus divides the parietal lobe and frontal lobe.
Second, the lateral sulcus (also known as the Sylvian fissure) separates the parietal lobe from the temporal lobe.
Lastly, the parietal lobe and occipital lobe are separated by the parieto-occipital sulcus.
Image: The central sulcus separates the parietal lobe (yellow) from the frontal lobe (blue). The lateral sulcus (Sylvian fissure) separates the parietal lobe (yellow) from the temporal lobe (green). The parieto-occipital sulcus separates the parietal lobe (yellow) from the occipital lobe (salmon).
Parietal Lobe Function = “Somatosensory”
Whenever you think of the overall function of the parietal lobe, think of the word “somatosensory”.
So what exactly does this mean?
The parietal lobe is involved in making us consciously aware of somatic sensations such as touch, pain, pressure, temperature, vibration, etc.
The parietal lobe also plays a key role in processing and analyzing somatosensory information to provide meaning and understanding to the stimulus.
Lastly, the parietal lobe is involved in proprioception as it processes sensory stimuli and provides us with spacial and body position awareness.
Image: The parietal lobe (yellow) is involved in awareness, processing, analyzing, and recognition of somatosensory stimuli such as touch, pain, temperature, pressure, vibration, etc. The parietal lobe also plays a role in proprioception.
Functional Cortical Areas - Parietal Lobe
There are specific cortical areas within the parietal lobe responsible for these somatosensory functions.
We are going to focus on 3 main cortical areas:
Primary Somatosensory Cortex
Somatosensory Association Cortex
Posterior Association Area
We will use the central sulcus as our starting point again.
1. Primary Somatosensory Cortex
Just posterior to the central sulcus is a gyrus called the postcentral gyrus, and it is the site of the functional area called the primary somatosensory cortex.
This is similar to the frontal lobe in which we had the precentral gyrus just anterior to the central sulcus, and this was the site of the primary motor cortex.
The primary somatosensory cortex is involved in conscious awareness of somatic sensations such as touch, pain, pressure, temperature, vibrations, etc.
The periphery sends somatic stimuli up through the spinal cord and into the primary somatosensory cortex where we become consciously aware of the stimulus.
The body can be mapped out on the primary somatosensory cortex similar to what we saw with the primary motor cortex.
The map will look similar in that the medial aspect of the primary somatosensory cortex receives somatic stimuli from the lower extremities, and the lateral aspect of the cortex receives information from the upper extremities and face.
Once a somatosensory stimulus reaches the primary somatosensory cortex we become consciously aware of it, but now we have to process and analyze the stimulus - which will bring us to the next functional area.
Image: The primary somatosensory cortex (red) is located posterior to the central sulcus on the postcentral gyrus. It is involved in conscious awareness of somatosensory stimuli such as touch, pain, temperature, pressure, vibrations, etc. The medial aspect of the primary somatosensory cortex receives somatosensory stimuli from the lower extremities, whereas the lateral aspect receives information from the upper extremities and face.
2. Somatosensory Association Cortex
Posterior to the primary somatosensory cortex is a functional area known as the somatosensory association cortex.
Again, we will continue to see the pattern of an association cortex with every primary cortex (like we saw in the frontal lobe - primary motor cortex and motor association cortex).
The function of the somatosensory association cortex is to analyze and process somatic stimuli.
We also compare the stimulus to old somatosensory memories and/or store them as new memories.
By analyzing, processing, and comparing the stimulus to old memories, we are able to recognize and understand what the somatosensory stimulus is.
For example, if we close our eyes (so there is no visual stimulus) and are handed an object such as an apple, we can feel the shape, size, firmness, and texture of the apple.
The somatosensory stimuli from the apple will be compared to old memories of when we have held an apple before, and we will be able to identify the object without looking at it.
It is the somatosensory association cortex that allows us to do this.
The somatosensory association cortex is also involved in proprioception and spacial awareness as we process somatic stimuli, but we will talk more about this in the next functional area below.
Image: The somatosensory association cortex (purple) is located posterior to the primary somatosensory cortex. It analyzes and processes somatosensory stimuli to help us recognize and understand the stimulus.
3. Posterior Association Area
The posterior association area is located in the posterior parietal lobe, and it also extends into the occipital and temporal lobe.
The somatosensory stimuli from the parietal lobe, the visual stimuli from the occipital lobe, and the auditory stimuli from the temporal lobe all meet in the posterior association area.
The union of somatosensory, visual, and auditory stimuli in the posterior association area is important for proprioception and allows us to develop spacial awareness of our body position and surroundings.
Image: The posterior association area (blue) is involved in proprioceptions and spacial awareness as it processes somatosensory stimuli from the parietal lobe, visual stimuli from the occipital lobe, and auditory stimuli from the temporal lobe.
Occipital Lobe
The next lobe is the occipital lobe, and it is located in the posterior brain.
Boundaries
There are 2 boundaries that separate the occipital lobe from the adjacent parietal and temporal lobes.
Parieto-Occipital Sulcus - Occipital and Parietal
Pre-Occipital Notch - Occipital and Temporal
First, the parieto-occipital sulcus divides the occipital lobe and parietal lobe.
The second boundary is not an actual sulcus, but rather an imaginary line. There is a “notch” in the brain where the temporal and occipital lobes meet, called the pre-occipital notch.
An imaginary line can be drawn from the pre-occipital notch up to the parieto-occipital sulcus, and this becomes the boundary between the occipital lobe and temporal lobe.
Image: The parieto-occipital sulcus separates the occipital lobe (salmon) from the parietal lobe (yellow). The imaginary line from the pre-occipital notch up to the parieto-occipital sulcus separates the occipital lobe (salmon) from the temporal lobe (green).
Occipital Lobe Function - “Vision”
Whenever you think of the overall function of the occipital lobe, think of the word “vision”.
The occipital lobe not only makes us consciously aware of visual stimuli, but it also helps us analyze, process, and recognize what the visual stimulus is.
Image: The occipital lobe (salmon) is involved in awareness, processing, analyzing, and recognition of visual stimuli.
Functional Cortical Areas - Occipital Lobe
Similar to how the frontal and parietal lobe had specific cortical areas that carried out their functions, the occipital lobe also has specific cortical areas.
We are going to focus on 2 main cortical areas:
Primary Visual Cortex
Visual Association Cortex
1. Primary Visual Cortex
The primary visual cortex is located in the posterior occipital lobe, and it functions to make us consciously aware of visual stimuli.
The eyes send visual information to the primary visual cortex, and we become consciously aware of the stimuli.
Now we have to process this information, and similar to above we will use an association cortex to analyze and understand the stimuli discussed next.
Image: The primary visual cortex (red) is located in the posterior occipital lobe, and it functions to make us consciously aware of visual stimuli.
2. Visual Association Cortex
The visual association cortex is located anterior to the primary visual cortex.
Similar to how the somatosensory association cortex helped analyze and recognize somatosensory stimuli, the visual association cortex helps us analyze and process visual stimuli.
Much of the information delivered from the eyes to the primary visual cortex will then be sent to the visual association cortex to be processed and analyzed.
The visual association cortex will compare visual stimuli to previous visual memories and/or form new memories.
The processing and analyzing of visual information will then provide meaning and understanding to the visual stimulus, and help us recognize what it is we are seeing.
Image: The visual association cortex (purple) is located anterior to the primary visual cortex (red). It analyzes and processes visual stimuli to help us recognize and understand the stimulus.
Temporal Lobe
The final main lobe is the temporal lobe, and it is located on the side of the brain.
Boundaries
There are 2 boundaries that separate the temporal lobe from the adjacent frontal, parietal, and occipital lobes.
Lateral Sulcus (Sylvian Fissure) - Temporal and Frontal/Parietal
Pre-Occipital Notch - Temporal and Occipital
First, the lateral sulcus (Sylvian fissure) separates the temporal lobe from the parietal and frontal lobes.
Second, the imaginary line from the pre-occipital notch to the parieto-occipital sulcus divides the temporal lobe and occipital lobe.
Image: The lateral sulcus (Sylvian fissure) separates the temporal lobe (green) from the frontal (blue) and parietal (yellow) lobes. The imaginary line from the pre-occipital notch to the parieto-occipital sulcus divides the temporal lobe (green) and the occipital lobe (salmon).
Temporal Lobe Function - “Auditory”
Whenever you think of the overall function of the temporal lobe, think of “auditory”.
The temporal lobe functions to make us consciously aware of auditory stimuli such as various pitches, frequencies, and sounds.
The temporal lobe also processes and analyzes auditory stimuli so we can recognize them.
Lastly, the temporal lobe is involved in the sense of smell as well.
Image: The temporal lobe (green) is involved in awareness, processing, analyzing, and recognition of auditory stimuli (along with smell and language comprehension discussed below).
Functional Cortical Areas - Temporal Lobe
There are specific cortical areas within the temporal lobe responsible for these auditory functions.
We are going to focus on 4 main cortical areas:
Primary Auditory Cortex
Auditory Association Cortex
Wernicke’s Area
Primary Olfactory Cortex/Olfactory Association Cortex
1. Primary Auditory Cortex
The primary auditory cortex functions to make us consciously aware of auditory stimuli.
Various pitches and frequencies enter our ears and this information will be sent to the primary auditory cortex where we become consciously aware of the sound.
Image: The primary auditory cortex (red) functions to make us consciously aware of auditory stimuli.
2. Auditory Association Cortex
Now that we are consciously aware of the auditory stimulus, we have to analyze and process it.
Sticking to the similar pattern we have seen for the other lobes, an association cortex will accomplish this - and in this case it is the auditory association cortex.
The auditory association cortex will analyze sounds, compare them to old auditory memories, and form new memories.
This analysis will help us recognize the sound and provide meaning and understanding to what it is we are hearing.
Image: The auditory association cortex (purple) analyzes and processes auditory stimuli to help us recognize and understand sounds.
3. Wernicke’s Area
Wernicke’s area is similar to Broca’s area in that it is usually in the dominant hemisphere.
Again, in most people this will be the left hemisphere as they are right-handed.
Wernicke’s area is involved in comprehension and understanding of written and spoken language.
Remember Broca’s area was involved in the production of speech and actual formation of words; Wernicke’s area is important for the understanding and comprehension of the language.
Image: Wernicke’s area (blue) is usually in the dominant hemisphere and is involved in comprehension and understanding of written and spoken language.
4. Primary Olfactory Cortex/Olfactory Association Cortex
Located deep in the temporal lobe on the medial aspect is the primary olfactory cortex and the olfactory association cortex.
The primary olfactory cortex makes us consciously aware of smells, and the olfactory association cortex helps us process and analyze those smells.
Image: The primary olfactory cortex and olfactory association cortex (orange) function to make us consciously aware of smells, as well as to analyze, process, and recognize smells.
Insular Cortex (Insular Lobe)
We have now covered the sense of touch (parietal lobe), vision (occipital lobe), auditory (temporal lobe), and smell (temporal lobe).
The final sense is taste.
In order to locate the functional cortical area that processes taste, we have to look deep into the lateral sulcus and pry apart the frontal and temporal lobes.
This area is called the insular cortex (also insula or insular lobe), and it functions to process taste, visceral sensations, autonomic control, and possibly vestibular control/equilibrium.
Image: The insular cortex is involved in taste, visceral sensation, autonomic control, and possibly vestibular information/equilibrium.
Limbic Lobe
The final area to discuss is the limbic lobe.
The limbic lobe is one structure of many that make up the limbic system.
However, some textbooks include the limbic lobe with the other cerebral lobes so we will briefly mention it here.
There will be a separate EZmed post that goes into more detail on the limbic system.
The main components of the limbic lobe are the cingulate gyrus, which surrounds the corpus callosum, and the parahippocampal gyrus.
The limbic lobe is one structure that makes up the limbic system, with some of the other main structures being the amygdala, hippocampal formation, thalamus, and hypothalamus.
The overall function of the limbic system includes learning, memory, emotions, behavior, and smell.
Image: The cingulate gyrus and parahippocampal gyrus are the main components of the limbic lobe. The limbic lobe is one structure of many that make up the limbic system. Limbic system functions include learning, memory, emotions, behavior, and smell.
Lobe Tricks
Let’s wrap this up with a few tricks that will help you remember the main functions of each lobe (the insular lobe is not included).
FRONTtal Lobe = FRONT engine/motor = Motor/Executive Func.
Think of a car motor/engine for the frontal lobe. The motor sits in the front of the car and is involved in moving the car and the executive functions of the vehicle.
The frontal lobe is the “motor” in the front of the brain that controls body movements and executive functioning.
Parietal Lobe = P’s = Somatosensory
Think of all the P’s when it comes to the parietal lobe - proprioception, pain, pressure, position and this will help you remember somatosensory stimuli.
OCccipital Lobe = BinOCulars = Vision
Think of binoculars for the occipital lobe, and this will help you remember vision.
TEMPOral Lobe = TEMPO = Auditory
Think of the tempo of songs and music for the temporal lobe, and this will help you remember auditory.
Limbic Lobe = L’s = Emotions/Memory
Think of the L’s for the limbic system - love and learning - and this will help you remember emotions and memory.
Image: Use these tricks to remember the main functions of each lobe.
Conclusion
Hopefully this was a good overview of the main lobes of the cerebral cortex along with their function and anatomy.
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