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| Basic structures of the forebrain |
The Forebrain
The forebrain (also known as the cerebrum) is the dominant part of the brain that you see in most pictures of the brain. The forebrain is the most evolved portion of the brain and is usually regarded as the seat of conscious thought. It has two basic components, the large cerebral hemispheres, and a set of specialized nerve clusters called the basal ganglia.
The left-right structures of the cerebral hemispheres look like the two halves of a giant walnut, and are situated at the top of the brain. The wrinkled surface of the cerebrum is also known as the cerebral cortex, or the neural cortex. The word ‘cortex’ simply means outer layer. The cortex has many folds that increase its surface area by a factor of three and consists of about ten billion neurons arranged in six thin layers. This grey matter is supported by a thicker layer of myelinated axons (white matter). The two cerebral hemispheres are connected by a thick band of cells called the corpus callosum. The cerebral hemispheres are essential to thought, memory, and personality. They receive, store, and interpret information from all over the body, and initiate voluntary actions.
The cerebral hemispheres are each divided by larger folds into four distinct lobes. See Figure #4. By the time impulses from neurons in your body reach this portion of your brain, they have switched sides. Lobes on the right side control processes on the left side of the body, and visa versa.
The forebrain (also known as the cerebrum) is the dominant part of the brain that you see in most pictures of the brain. The forebrain is the most evolved portion of the brain and is usually regarded as the seat of conscious thought. It has two basic components, the large cerebral hemispheres, and a set of specialized nerve clusters called the basal ganglia.
The left-right structures of the cerebral hemispheres look like the two halves of a giant walnut, and are situated at the top of the brain. The wrinkled surface of the cerebrum is also known as the cerebral cortex, or the neural cortex. The word ‘cortex’ simply means outer layer. The cortex has many folds that increase its surface area by a factor of three and consists of about ten billion neurons arranged in six thin layers. This grey matter is supported by a thicker layer of myelinated axons (white matter). The two cerebral hemispheres are connected by a thick band of cells called the corpus callosum. The cerebral hemispheres are essential to thought, memory, and personality. They receive, store, and interpret information from all over the body, and initiate voluntary actions.
The cerebral hemispheres are each divided by larger folds into four distinct lobes. See Figure #4. By the time impulses from neurons in your body reach this portion of your brain, they have switched sides. Lobes on the right side control processes on the left side of the body, and visa versa.
As the name implies, the frontal lobes are located at the front of the brain, just behind your forehead. Your most advanced thinking and decision-making occur in the frontal lobes. Your personality and intelligence are thought to reside here. The motor cortex in each frontal lobe controls all your voluntary muscular activity. The right motor cortex lies in a band from the top of your head down towards your right temple. The portion near the top controls the movement of your lower left body and the portion near your right temple controls the muscles on the left side of your face.
The frontal lobes also contain Broca’s area devoted to generating speech, and other regions related to understanding, learning, thinking, and planning.
The parietal lobes lie just behind the frontal lobes and extend towards the back of your head. The parietal lobes contain the somatosensory cortex, a region that receives sensory input from all parts of your body. A map of the surface of your body can be traced out on the somatosensory cortex.
The parietal lobes lie just behind the frontal lobes and extend towards the back of your head. The parietal lobes contain the somatosensory cortex, a region that receives sensory input from all parts of your body. A map of the surface of your body can be traced out on the somatosensory cortex.
The occipital lobes are located at the very back of the head and are devoted to vision. If you happen to get hit in the back of the head you sometimes ‘see stars’ because the occipital lobes have been jarred and spurious neural signals are generated.
The temporal lobes are located at the side of the head, just inside the ears.
Appropriately, the temporal lobes contain the auditory cortex that is responsible for the ears and hearing. The temporal lobes also contain Wernicke’s area; a region devoted to understanding speech.
The basal ganglia are small and specialized clusters of cells involved with the control of movement. They are found inside the white matter beneath the cerebral cortex.
This introduction to the anatomy of the brain has touched on the major structures at work in your brain. There are also several large spaces in the brain, called ventricles, that are filled with cerebral fluid. The cerebral fluid circulates through the ventricles transporting hormones, removing waste, and helping to support the structure of the brain.
The temporal lobes are located at the side of the head, just inside the ears.
Appropriately, the temporal lobes contain the auditory cortex that is responsible for the ears and hearing. The temporal lobes also contain Wernicke’s area; a region devoted to understanding speech.
The basal ganglia are small and specialized clusters of cells involved with the control of movement. They are found inside the white matter beneath the cerebral cortex.
This introduction to the anatomy of the brain has touched on the major structures at work in your brain. There are also several large spaces in the brain, called ventricles, that are filled with cerebral fluid. The cerebral fluid circulates through the ventricles transporting hormones, removing waste, and helping to support the structure of the brain.
