Caustic Regular Dr. Rob Tarzwell joins Joe, Toren, and Kevin in the premiere episode of our new series: “Caustic Anatomy Class”, this episode focusing on the master control of it all: the brain! We’ll talk about the history of brain knowledge, an introduction to the brain’s structure, brain-eating amoebas, the “creepy threesome”, several people walking and talking without a large part of their brain, brain tapeworms, and The Man With Two Brains and a skull-full of pop culture!
Music: “Scatter Brain” by Frankie Masters And His Orchestra
- Caustic Anatomy Class Intro music from Creative Sound.
- Brain in a Jar trope
- Fungi from Yuggoth
- The Whisper in the Darkness
Anatomy of the Brain
collated by Caustic researcher Cory
The most common method used to divide the brain, is based on the three main regions that developed in the embryonic state:
The Forebrain (or prosencephalon)
- the cerebrum (telencephalon)
- hypothalamus and pineal gland among other features (diencephalon, or interbrain).
The Midbrain (or mesencephalon)
located near the very center of the brain between the interbrain and the hindbrain, is composed of a portion of the brainstem.
The Hindbrain (or rhombencephalon)
Consists of the remaining brainstem (myelencephalon) as well as our cerebellum and pons (metencephalon).
Brain cells can be broken into two groups:
- Neurons, or nerve cells, are the cells that perform all of the communication and processing within the brain.
- Neuroglia, or glial cells, act as the helper cells of the brain; they support and protect the neurons. In the brain there are four types of glial cells:
- Astrocytes which protect neurons by filtering nutrients out of the blood and preventing chemicals and pathogens from leaving the capillaries of the brain. They have also been observed to turn into neurons by virtue of the stem cell characteristic pluripotency.
- Oligodendrocytes wrap the axons of neurons in the brain to produce the insulation known as myelin.
- Microglia act much like white blood cells by attacking and destroying pathogens that invade the brain.
- Ependymal cells line the capillaries of the choroid plexuses and filter blood plasma to produce cerebrospinal fluid.
The tissue of the brain can be broken down into two major classes: gray matter and white matter.
- Gray matter is made of mostly unmyelinated neurons, most of which are interneurons. The gray matter regions are the areas of nerve connections and processing.
- White matter is made of mostly myelinated neurons that connect the regions of gray matter to each other and to the rest of the body.
Myelinated neurons transmit nerve signals much faster than unmyelinated axons do. You could imagine your brain’s gray matter as suburbs and businesses, and the white matter as the express highway, carrying information to be processed.
Parts of the Brain
The cerebrum is the largest portion of the brain, and is responsible for most of the brain’s function. It is divided into four sections:
- Frontal Lobe: Controls several elements including creative thought, problem solving, intellect, judgment, behavior, attention, abstract thinking, physical reactions, muscle movements, coordinated movements, smell and personality.
- Parietal Lobe: This lobe focuses on comprehension. Visual functions, language, reading, internal stimuli, tactile sensation and sensory comprehension are monitored here.
- Sensory Cortex – This receives information relayed from the spinal cord regarding the position of various body parts and how they are moving. This middle area of the brain can also be used to relay information from the sense of touch, including pain or pressure which is affecting different portions of the body.
- Motor Cortex– This helps the brain monitor and control movement throughout the body. It is located in the top, middle portion of the brain.
- Temporal Lobe: Controls visual and auditory memories. It includes areas that help manage some speech and hearing capabilities, behavioral elements, and language.
- Wernicke’s Area – This portion of the temporal lobe is formed around the auditory cortex. While scientists have a limited understanding of the function of this area, it is known that it helps the body formulate and understand speech.
- Occipital Lobe: Helps to control vision.
- Broca’s Area – Functions linked to the production of speech and language.
This is commonly referred to as “the little brain,” and is considered to be older than the cerebrum on the evolutionary scale. The cerebellum controls essential body functions such as balance, posture and coordination.
The limbic system contains glands which help relay emotions. Many hormonal responses that the body generates are initiated in this area. The limbic system includes the amygdala, hippocampus, hypothalamus and thalamus.
- Amygdala: The amygdala helps the body responds to emotions, memories and fear.
- Hippocampus: Used for learning memory, specifically converting temporary memories into permanent memories which can be stored within the brain. The hippocampus also helps people analyze and remember spatial relationships, allowing for accurate movements.
- Hypothalamus: The hypothalamus region of the brain controls mood, thirst, hunger and temperature. It also contains glands which control the hormonal processes throughout the body.
- Thalamus: The Thalamus is located in the center of the brain. It helps to control the attention span, sensing pain and monitors input that moves in and out of the brain to keep track of the sensations the body is feeling.
All basic life functions originate in the brain stem, including heartbeat, blood pressure and breathing. The brain stem consists of midbrain, pons and medulla.
- Midbrain: The midbrain, also known as the mesencephalon is made up of the tegmentum and tectum. These parts of the brain help regulate body movement, vision and hearing.
- Pons: Links to the cerebellum to help with posture and movement. It interprets information that is used in sensory analysis or motor control. The pons also creates the level of consciousness necessary for sleep.
Medulla: The medulla or medulla oblongata maintains vital body functions such as the heart rate and breathing.