As the absolute control center of the central nervous system and, therefore, the entire human body, the brain manages everything we do and need, from moving our limbs to retaining memories to keeping our heart beating. And to accomplish these amazing feats every second of every day, myriad individual parts need to do their specific jobs.
There are three main portions of the brain: the cerebrum, the largest portion, is itself made of distinct parts, known as hemispheres which, in turn, are further divided into lobes. The frontal lobes dictate our personalities and manage such traits as behavior, emotion and logic; the parietal lobes are where are senses are registered; shapes and colors are processed within the occipital lobes; and senses and memories come from the temporal lobes.
The second major portion of the brain is the cerebellum, found below the cerebrum at the rear of the brain. This section is responsible for helping us move and maintain posture, balance and muscle coordination. And the third major portion is the brain stem, located in front of the cerebellum and below the cerebrum. Here a host of involuntary functions are regulated, including respiration and heartbeat as well as digestion. Additionally, the brain stem is responsible for relaying information between the brain and spinal cord.
The Brain Glossary
Corpus Callosum: a large grouping of nerves that connect the two hemispheres of the brain and allow for communication between them.
Fornix: also a collection of nerve fibers, the fornix connects the hypothalamus to portions of the inner brain
Thalamus: information from the sensory organs of the body is relayed through the thalamus, located at the top of the brain stem.
Hypothalamus: everything from specific behaviors to body temperature regulation to critical urges are managed by the hypothalamus.
Midbrain: the visual and auditory functions of our bodies are controlled here.
Pons: responsible for the regulation of sleep patterns, movement and certain involuntary functions.
Medulla Oblongata: this vital portion of the brain stem controls respiration and breathing and gives us the ability to swallow and have reflexive movements.
Pineal Gland: creates and distributes meltonin, which aids in sleep.
Pituitary Gland: the head of the endocrine system, the pituitary gland controls our growth rates as well as urges of hunger and sexual desire through the regulation of other glands that secrete hormones.
The Bones of the Head
There are 22 bones comprising the skull, eight of which are directly responsible for protecting the brain and 14 of which form the structures of our faces and provide openings for air and sustenance.
The eight bones protecting our brain are known as the cranium: one front bone is in the forehead while two form the upper sides of the skull and two form the lower sides. Another, the ethmoid, creates a space between the nasal cavity and the brain at the roof of the mouth between the eye sockets. Two other bones—the occipital and the sphenoid—form the back and the base of the skull.
The 14 bones comprising our facial structure all exist as pairs: the upper jaw and front of the palate are the maxillae; the rear of the palate is the palantine; the lower jaw is composed of the mandible and the maxillae and anchor the teeth; the zygomatic bones form our cheeks and the nasal bones the bridge of our nose; lacrimal bones form part of our eye sockets; the inferior nasal conchae divides our nasal cavity; and the vomer divides the nostrils at the nasal septum.
Found throughout the skull are small holes known as foraminae, which exist to allow for blood vessels—such as the carotid arteries—as well as nerves to enter and leave the skull. The largest of these holes is known as the foramen magnum, through which the spinal cord joins with the brain, and is the site of condyles, which, in conjunction with the first vertebra, allow us to move our heads up and down.
When we’re born, the bones of our skull are not yet fused together, and are instead connected by soft membranes known as fontanels, which allow for the skull to compress during birth and grow during infancy. By the time the human body reaches approximately two years old these bones complete their fusing: at this point the fontanels have been replaced by strong joints known as sutures. And in adulthood, the only bone of our skull not yet fused is the mandible (lower jaw), which needs to be able to open and shut.
Simply put, tumors are abnormal growths due to unnecessary cell multiplication that serves no proper function in the human body. Typically, cell multiplication is controlled by suppressor genes, which continually act to protect cells from cancer-causing genes known as oncogenes. However, when suppressor genes fail because of changes in their protein coding, tumor can develop as cell division becomes unregulated.
Whereas our body’s built-in defenses find and destroy these abnormal cells, naturally occurring chemicals sometimes hamper the ability of our immune system to see these cells, as which point they become strong enough and exist in large enough numbers to overpower any of body’s defenses.