Cerebrum vs Cerebral Cortex
The nervous system is important to control and coordinate all the actions of an organism and transmit signals between different parts of the body. The system is basically made up of specialized cells called neurons. The complexity of the nervous system increases with the complexity of the body of organisms. Most primitive animals like sponges, flatworms have a very simple nervous system while advanced animals like vertebrates have a highly complex nervous system with larger brains. Brain is one of the largest and most amazing organs in an organism that can be categorized under the central nervous system. The human brain can be divided into three categories, namely, forebrain, midbrain and hindbrain. Both the cerebrum and cerebral cortex come under the forebrain.
Cerebrum is the largest and most prominent part of the human brain. It appears to envelop the rest of the brain as it constitutes 4/5 of its weight. It is split longitudinally into two large, prominent hemispheres; left and right by deep median fissure called ‘cerebral fissure’. These two hemispheres are connected through a horizontal sheet of nerve fibers known as corpus callosum. Each hemisphere is further divided into the frontal, parietal, temporal, and occipital lobes by three deep fissures, namely, central, parieto-occipital and sylvian fissure. Each hemisphere receives sensory input from the contra lateral side of the body and exerts motor control over that side. The basic function of the cerebrum is to control voluntary functions and seat of intelligence, will power, memory, reasoning, thinking, learning, emotions, speech etc.
The layer of gray matter, about 2 to 4mm thickness, on the outer surface of the cerebrum is called the cerebral cortex. In humans, the cerebral cortex is densely packed with over 10 billion nerve cells (about 10% of all the neurons in the brain) and, therefore, much of the neural activities of the cerebrum take place within this layer.
The outer surface of the cerebral cortex is highly convoluted, and this convoluted surface increases the surface area of the cerebral cortex. The ridges of these convolutions are called ‘gyri’ and depressions between them as ‘sulci’. Each region is responsible for a particular function. According to the function or activity, the regions of the cerebral cortex can be divided into three general categories, namely, motor, sensory, and associative.
The motor cortex is generally associated with the movement of body parts and sensory cortex such as auditory cortex, visual cortex etc. is associated with sensory organs. There is a portion of the cerebral cortex which is not occupied by motor and sensory cortices, known as the ‘association cortex’. This region is devoted for higher mental activities, so that in higher primates, especially in humans, it covers 95% of the total cerebral cortex surface.
What is the difference between Cerebrum and Cerebral Cortex?
• Cerebral cortex is a part of the cerebrum.
• Cerebrum is the largest and most prominent part of the brain whereas cerebral cortex is the outer layer of the cerebrum.
• Cerebrum has both gray and white matter while the gray part of it is considered as the cerebral cortex.
• Human cerebral cortex is made up of approximately 10 billion nerve cell bodies and their dendrites whereas the cerebrum has both cell bodies and nerve fibers.