A journey of the brain and the ventricles within the CSF
-Mauro Zappaterra, MD, PhD.
We are going to start in the lateral ventricle on the right side. Gently feel yourself floating in the CSF. Imagine yourself as a molecule within the fluid or a raft floating on water. Start to get a sense of the fluid that you are. Relax. Now open your minds eye, you are in the CSF with walls of tissue all around you, this tissue is brain tissue.
This is a large opening, with lots of space. You are in the Central Portion of the lateral ventricle, this is within the parietal lobe, very important for integrating sensory information, if you look up at the roof and to the right, you see the corpus callosum these are nerve fibers that connect the left and right cerebral hemispheres (lobes of the brain), if you look down, you see the floor. Along the floor you see the tissues making up the fornix (carries signals that integrate memory (hippocampus) with body temperature, hunger/thirst, fatigue, circadian cycles, parenting and attachment behaviors (hypothalamus), the thalamus (a major relay station and filter for sensory and motor signals, as well as awareness, arousal, and sleep/wake cycles), stria terminalis (regulates acute stress response, and anxiety) (output pathway of amygdala going to hypothalamus), caudate nucleus (learning, memory, emotion and language comprehension) and the choroid plexus, and now if you look to the left you see the septum pellucidum (a thin veil of tissue separating the two hemispheres of the brain. If you start floating forward or towards your eyes, you move anteriorly into the frontal lobe, important for executive functioning and the limbic system, integrating rewards, attention, short term memory, planning and motivation. Here again looking up you see the corpus callosum, looking down and to the right you see the caudate, and looking to the left you see the septum pellucidum. Now start floating back towards the back of your head, going back through the central portion of the ventricle and into the posterior part of the brain. You are now in the occipital lobe, the major area of visual processing. Again looking up we see the corpus callosum, looking to the right we see the optic radiations which carries visual information to the brain and then to the left we see the forceps major, the main path for the two occipital lobes to the communicate. Now moving our raft or minds eye forward and a little down going towards your ears, we enter the last part of the lateral ventricle, the inferior or temporal part, located in the temporal lobe, important for memory, language and deriving meaning. Looking up we see the temporal lobe itself, looking straight ahead to the end of the ventricle we see the amygdala (important for processing of memory and emotional reactions), to the right me see the stria terminalis again and tail of the caudate, looking towards the floor of the ventricle we see the hippocampus (memory processing).
Now lets float back to the posterior part, and then up into the central part where we began. When you are in the central part, if you look down and to the left there is a little narrow opening, the foramen of Monro. Lets now flow and move your minds eye through the opening on the left, and go through it.
You enter the third ventricle. It is a narrow vertical cavity along the midline of the brain at about the height of the third eye. Feel yourself in this narrow vertical cavity. Start by gazing upward. When you are in the third ventricle and you look up or at the roof you see the fornix, the corpus collosum and two openings to the right and left, these holes lead into the lateral ventricles. Now look to your right and your left, the walls of the 3rd ventricle are made by the thalamus (a major relay station and filter for sensory and motor signals, as well as awareness, arousal, and sleep/wake cycles) and hypothalamus (links nervous system to endocrine system. Body temperature, hunger, parenting and attachment behaviors, thirst, fatigue, sleep, circadian cycles). Look directly in front of you, you see the anterior commissure (plays a key role in pain and pain sensation. It also works with the posterior commissure to link the two cerebral hemispheres of the brain and connects the amygdalas and temporal lobes, contributing to the role of memory, emotion, speech and hearing. It also is involved in smell, instinct, and sexual behavior), and optic chiasm (the crossing of the optic nerves). Now look behind you, staring at you is the pineal gland (melatonin, sleep/wake cycles, “third eye”). Take in the pineal gland. Recognize that the pineal gland can directly release molecules into the CSF. Now look below you to the floor of the 3rd ventricle and you will find the infundibulum (connection between hypothalamus and posterior pituitary (releases oxytocin “love hormone” and vasopressin (water retention, vasoconstriction, social behavior, sexual motivation, bonding).
Now look down and a little to the back of the brain, there is a single narrow opening called the aqueduct of Sylvius or cerebral aqueduct. Go through this narrow opening, and you enter the fourth ventricle. This is a diamond shaped cavity. It is located posterior to the pons (bridge of the brain to the spinal cord and cerebellum) and the medulla (autonomic functions (breathing, HR, BP)) and anterior to the cerebellum (motor control, coordination). The top or roof is made of the cerebellar peduncles (connections from the cerebellum to the brain and spinal cord) and the midbrain (carries nerve fibers from brain to spinal cord, important for motor control, arousal, alertness, and temperature regulation). Looking to the floor you see a rhomboid shape that makes up one point of the diamond shaped cavity. This point goes through the medulla and creates a path down the center of the entire spinal cord. Dive into the path and go all the way down the spinal cord.
Become absorbed in the spinal cord, and then into the whole rest of the body, and return to your heart.