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.
Brain Structure and Function
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. It plays a role in controlling functions such as eating, sexual behavior and sleeping; and regulates body temperature, emotions, secretion of hormones and movement. The pituitary gland develops from an extension of the hypothalamus downwards and from a second component extending upward from the roof of the mouth. Once the information passes from the optic nerve to the rest of the brain, it is sent to the occipital lobe, where sight is processed.
The occipital lobe is located in the back of the brain, above the cerebellum, and forms the center of the visual perception system, according to the Centre for Neuro Skills. Each hemisphere has its own occipital lobe; therefore, each occipital lobe processes the information sent to that specific hemisphere. The occipital lobe controls how a person perceives sight, so damage to this brain section can result in visual field cuts, and problems identifying color or movement of an object.
The last part of the brain involved in sight is the visual cortex, where sensory and motor information is integrated with vision. The Canadian Institutes of Health Research states that multiple visual pathways are involved. For example, the ventral visual pathway controls how a person identifies objects, while the dorsal visual pathway controls a person's visual-motor response to objects. StatPearls [Internet]. Accessed June 22, The brainstem: anatomy, assessment, and clinical syndromes. J Neuropsychiatry Clin Neurosci. Cerebellar granule cells encode the expectation of reward.
Fama R, Sullivan EV. Thalamic structures and associated cognitive functions: Relations with age and aging.
The Nervous System
Neurosci Biobehav Rev. Role of developmental factors in hypothalamic function. Front Neuroanat. Anand KS, Dhikav V. Hippocampus in health and disease: An overview. Ann Indian Acad Neurol.
A Guide to the Anatomy of the Brain
Functional neuroanatomy of the basal ganglia. Cold Spring Harb Perspect Med. More in Theories. The frontal lobe is located at the front of the brain and is associated with reasoning, motor skills, higher level cognition, and expressive language. At the back of the frontal lobe, near the central sulcus, lies the motor cortex. This area of the brain receives information from various lobes of the brain and utilizes this information to carry out body movements.
Damage to the frontal lobe can lead to changes in sexual habits, socialization, and attention as well as increased risk-taking. The parietal lobe is located in the middle section of the brain and is associated with processing tactile sensory information such as pressure, touch, and pain. A portion of the brain known as the somatosensory cortex is located in this lobe and is essential to the processing of the body's senses.
The temporal lobe is located on the bottom section of the brain.
This lobe is also the location of the primary auditory cortex, which is important for interpreting sounds and the language we hear. The hippocampus is also located in the temporal lobe, which is why this portion of the brain is also heavily associated with the formation of memories. Damage to the temporal lobe can lead to problems with memory, speech perception, and language skills. The occipital lobe is located at the back portion of the brain and is associated with interpreting visual stimuli and information.
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The primary visual cortex, which receives and interprets information from the retinas of the eyes, is located in the occipital lobe. Damage to this lobe can cause visual problems such as difficulty recognizing objects, an inability to identify colors, and trouble recognizing words.
The midbrain is often considered the smallest region of the brain.