Have you ever looked at the anatomy of the human brain? Indeed, it is a three-pound marvel of such complexity, it is challenging to process all the information about the organ. How does it control the body, form thoughts and embody the essence of the mind and spirit (a/k/a the soul)? As much as we know, there is so much we do not know. Life is a mystery ... beginning with the human brain.
Consider the areas of the brain for yourself:
Figure 3. The brain is composed of three parts: the brainstem, cerebellum, and cerebrum.
The cerebrum is divided into four lobes: frontal, parietal, temporal, and occipital.
- The cerebrum is the largest part of the brain and is composed of the right and left hemispheres. It performs higher functions like interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning and fine control of movement.
- The cerebellum is located under the cerebrum. Its function is to coordinate muscle movements, maintain posture, and balance.
- The brainstem includes the midbrain, pons, and medulla. It acts as a relay center connecting the cerebrum and cerebellum to the spinal cord. It performs many automatic functions such as breathing, heart rate, body temperature, wake and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing. Ten of the twelve cranial nerves originate in the brainstem.
The surface of the cerebrum has a folded appearance called the cortex. The cortex contains about 70% of the 100 billion nerve cells. The nerve cell bodies color the cortex grey-brown giving it its name – gray matter (Fig. 4). Beneath the cortex are long connecting fibers between neurons, called axons, which make up the white matter.
Figure 4. The surface of the cerebrum is called the cortex. The cortex contains neurons (grey matter), which are interconnected to other brain areas by axons (white matter). The cortex has a folded appearance. A fold is called a gyrus and the groove between is a sulcus.
The folding of the cortex increases the brain’s surface area allowing more neurons to fit inside the skull and enabling higher functions. Each fold is called a gyrus, and each groove between folds is called a sulcus. There are names for the folds and grooves that help define specific brain regions.
Right brain – left brain
The right and left hemispheres of the brain are joined by a bundle of fibers called the corpus callosum that delivers messages from one side to the other. Each hemisphere controls the opposite side of the body. If a brain tumor is located on the right side of the brain, your left arm or leg may be weak or paralyzed.
Not all functions of the hemispheres are shared. In general, the left hemisphere controls speech, comprehension, arithmetic, and writing. The right hemisphere controls creativity, spatial ability, artistic, and musical skills. The left hemisphere is dominant in hand use and language in about 92% of people.
Lobes of the brain
The cerebral hemispheres have distinct fissures, which divide the brain into lobes. Each hemisphere has 4 lobes: frontal, temporal, parietal, and occipital (Fig 3). Each lobe may be divided, once again, into areas that serve very specific functions. It’s important to understand that each lobe of the brain does not function alone. There are very complex relationships between the lobes of the brain and between the right and left hemispheres.
Frontal lobe
Personality, behavior, emotions
Judgment, planning, problem solving
Speech: speaking and writing (Broca’s area)
Body movement (motor strip)
Intelligence, concentration, self awareness
Parietal lobe
- Interprets language, words
- Sense of touch, pain, temperature (sensory strip)
- Interprets signals from vision, hearing, motor, sensory and memory
- Spatial and visual perception
Occipital lobe
- Interprets vision (color, light, movement)
Temporal lobe
- Understanding language (Wernicke’s area)
- Memory
- Hearing
- Sequencing and organization
Messages within the brain are carried along pathways. Messages can travel from one gyrus to another, from one lobe to another, from one side of the brain to the other, and to structures found deep in the brain (e.g. thalamus, hypothalamus).
Honestly, my poor brain can barely process all this wealth of information, which explains why I only took 6 hours of science in college (i.e. chemistry ... and not my idea either). I had to study like the dickens! Under the gun, I can sometimes recall a bit of the subject, and as the years pass, there's a lot of other crap up there too. Oh well, I digress ...
Enjoy the weekend, and always take good care of your magnificent brain.
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