The third ventricle connects with the fourth ventricle through a long tube called the Aqueduct of Sylvius. CSF flowing through the fourth ventricle flows around the brain and spinal cord by passing through another series of openings. The brainstem is the lower extension of the brain, located in front of the cerebellum and connected to the spinal cord. It consists of three structures: the midbrain, pons and medulla oblongata.
It serves as a relay station, passing messages back and forth between various parts of the body and the cerebral cortex. Many simple or primitive functions that are essential for survival are located here. The midbrain is an important center for ocular motion while the pons is involved with coordinating eye and facial movements, facial sensation, hearing and balance.
The medulla oblongata controls breathing, blood pressure, heart rhythms and swallowing. Messages from the cortex to the spinal cord and nerves that branch from the spinal cord are sent through the pons and the brainstem. Destruction of these regions of the brain will cause "brain death. The reticular activating system is found in the midbrain, pons, medulla and part of the thalamus.
It controls levels of wakefulness, enables people to pay attention to their environments and is involved in sleep patterns. Originating in the brainstem are 10 of the 12 cranial nerves that control hearing, eye movement, facial sensations, taste, swallowing and movements of the face, neck, shoulder and tongue muscles.
The cranial nerves for smell and vision originate in the cerebrum. Four pairs of cranial nerves originate from the pons: nerves five through eight. The cerebellum is located at the back of the brain beneath the occipital lobes. It is separated from the cerebrum by the tentorium fold of dura. The cerebellum fine tunes motor activity or movement, e.
It helps one maintain posture, sense of balance or equilibrium, by controlling the tone of muscles and the position of limbs. The cerebellum is important in one's ability to perform rapid and repetitive actions such as playing a video game.
In the cerebellum, right-sided abnormalities produce symptoms on the same side of the body. The cerebrum, which forms the major portion of the brain, is divided into two major parts: the right and left cerebral hemispheres.
The cerebrum is a term often used to describe the entire brain. A fissure or groove that separates the two hemispheres is called the great longitudinal fissure. The two sides of the brain are joined at the bottom by the corpus callosum. The corpus callosum connects the two halves of the brain and delivers messages from one half of the brain to the other.
The surface of the cerebrum contains billions of neurons and glia that together form the cerebral cortex. The cerebral cortex appears grayish brown in color and is called the "gray matter. The cerebral cortex has sulci small grooves , fissures larger grooves and bulges between the grooves called gyri. Scientists have specific names for the bulges and grooves on the surface of the brain. Decades of scientific research have revealed the specific functions of the various regions of the brain. Beneath the cerebral cortex or surface of the brain, connecting fibers between neurons form a white-colored area called the "white matter.
The cerebral hemispheres have several distinct fissures. By locating these landmarks on the surface of the brain, it can effectively be divided into pairs of "lobes. The cerebrum or brain can be divided into pairs of frontal, temporal, parietal and occipital lobes.
Each hemisphere has a frontal, temporal, parietal and occipital lobe. Each lobe may be divided, once again, into areas that serve very specific functions. The lobes of the brain do not function alone: they function through very complex relationships with one another.
Messages within the brain are delivered in many ways. The signals are transported along routes called pathways. Any destruction of brain tissue by a tumor can disrupt the communication between different parts of the brain. The result will be a loss of function such as speech, the ability to read or the ability to follow simple spoken commands. Messages can travel from one bulge on the brain to another gyri to gyri , from one lobe to another, from one side of the brain to the other, from one lobe of the brain to structures that are found deep in the brain, e.
Research has determined that touching one side of the brain sends electrical signals to the other side of the body. Touching the motor region on the right side of the brain would cause the opposite side or the left side of the body to move. Stimulating the left primary motor cortex would cause the right side of the body to move. The messages for movement and sensation cross to the other side of the brain and cause the opposite limb to move or feel a sensation.
The right side of the brain controls the left side of the body and vice versa. So if a brain tumor occurs on the right side of the brain that controls the movement of the arm, the left arm may be weak or paralyzed. There are 12 pairs of nerves that originate from the brain itself.
These nerves are responsible for very specific activities and are named and numbered as follows:. The hypothalamus is a small structure that contains nerve connections that send messages to the pituitary gland.
The hypothalamus handles information that comes from the autonomic nervous system. Aphasia is a disturbance of language affecting speech production, comprehension, reading or writing, due to brain injury — most commonly from stroke or trauma.
The type of aphasia depends on the brain area damaged. If this area is damaged, one may have difficulty moving the tongue or facial muscles to produce the sounds of speech.
The person can still read and understand spoken language but has difficulty in speaking and writing i. Wernicke's area: lies in the left temporal lobe Fig 3. Damage to this area causes Wernicke's aphasia. The individual may speak in long sentences that have no meaning, add unnecessary words, and even create new words. They can make speech sounds, however they have difficulty understanding speech and are therefore unaware of their mistakes.
The surface of the cerebrum is called the cortex. It has a folded appearance with hills and valleys. The nerve cell bodies color the cortex grey-brown giving it its name — gray matter Fig. Beneath the cortex are long nerve fibers axons that connect brain areas to each other — called white matter. 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. Pathways called white matter tracts connect areas of the cortex to each other.
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 deep in the brain Fig. Hypothalamus: is located in the floor of the third ventricle and is the master control of the autonomic system.
It plays a role in controlling behaviors such as hunger, thirst, sleep, and sexual response. It also regulates body temperature, blood pressure, emotions, and secretion of hormones. Pituitary gland: lies in a small pocket of bone at the skull base called the sella turcica. The pituitary gland is connected to the hypothalamus of the brain by the pituitary stalk.
It secretes hormones that control sexual development, promote bone and muscle growth, and respond to stress. Pineal gland : is located behind the third ventricle. It has some role in sexual development. Thalamus : serves as a relay station for almost all information that comes and goes to the cortex. It plays a role in pain sensation, attention, alertness and memory.
Basal ganglia: includes the caudate, putamen and globus pallidus. These nuclei work with the cerebellum to coordinate fine motions, such as fingertip movements. Limbic system: is the center of our emotions, learning, and memory.
Included in this system are the cingulate gyri, hypothalamus, amygdala emotional reactions and hippocampus memory. Memory is a complex process that includes three phases: encoding deciding what information is important , storing, and recalling. Different areas of the brain are involved in different types of memory Fig. Your brain has to pay attention and rehearse in order for an event to move from short-term to long-term memory — called encoding.
The brain has hollow fluid-filled cavities called ventricles Fig. Inside the ventricles is a ribbon-like structure called the choroid plexus that makes clear colorless cerebrospinal fluid CSF.
CSF flows within and around the brain and spinal cord to help cushion it from injury. This circulating fluid is constantly being absorbed and replenished.
There are two ventricles deep within the cerebral hemispheres called the lateral ventricles. They both connect with the third ventricle through a separate opening called the foramen of Monro. The third ventricle connects with the fourth ventricle through a long narrow tube called the aqueduct of Sylvius. From the fourth ventricle, CSF flows into the subarachnoid space where it bathes and cushions the brain. CSF is recycled or absorbed by special structures in the superior sagittal sinus called arachnoid villi.
A balance is maintained between the amount of CSF that is absorbed and the amount that is produced. A disruption or blockage in the system can cause a build up of CSF, which can cause enlargement of the ventricles hydrocephalus or cause a collection of fluid in the spinal cord syringomyelia. The purpose of the bony skull is to protect the brain from injury.
The skull is formed from 8 bones that fuse together along suture lines. This gland is a big player in puberty too. This is the time when boys' and girls' bodies go through major changes as they slowly become men and women, all thanks to hormones released by the pituitary gland. This little gland also plays a role with lots of other hormones, like ones that control the amount of sugars and water in your body.
The hypothalamus is like your brain's inner thermostat that little box on the wall that controls the heat in your house. The hypothalamus knows what temperature your body should be about If your body is too hot, the hypothalamus tells it to sweat. If you're too cold, the hypothalamus gets you shivering. Both shivering and sweating are attempts to get your body's temperature back where it needs to be.
So the brain is boss, but it can't do it alone. It needs some nerves — actually a lot of them. And it needs the spinal cord, which is a long bundle of nerves inside your spinal column, the vertebrae that protect it. It's the spinal cord and nerves — known as the nervous system — that let messages flow back and forth between the brain and body. If a spiky cactus falls off a shelf headed right for your best friend, your nerves and brain communicate so that you jump up and yell for your friend to get out of the way.
If you're really good, maybe you're able to catch the plant before it hits your friend! The nervous system is made up of millions and millions of neurons say: NUR-onz , which are microscopic cells. Each neuron has tiny branches coming off it that let it connect to many other neurons. When you learn things, the messages travel from one neuron to another, over and over. Eventually, the brain starts to create connections or pathways between the neurons, so things become easier and you can do them better and better.
Think back to the first time you rode a bike. Your brain had to think about pedaling, staying balanced, steering with the handlebars, watching the road, and maybe even hitting the brakes — all at once. Hard work, right? But eventually, as you got more practice, the neurons sent messages back and forth until a pathway was created in your brain. Now you can ride your bike without thinking about it because the neurons have successfully created a "bike riding" pathway.
With all the other things it does, is it any surprise that the brain runs your emotions? Maybe you had fun on your birthday and you were really happy. Or your friend is sick and you feel sad. Or your little brother messed up your room, so you're really angry! Where do those feelings come from? Your brain, of course.
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