hi and welcome to today's lecture today we'll be learning all about the human brain we'll discuss the major sub-regions and functions of the brain stem cerebellum diencephalon and cerebrum we'll take a look at the motor sensory and association areas of the cerebrum we'll then finish up by examining the limbic system and the cerebral white matter I feel like this is a lecture that might give you a lot to think about let's go ahead and get started the brain stem is the most inferior region of the brain it connects directly to the spinal cord and contains many autonomic and reflex centers required for our survival it also gives rise to many of the cranial nerves the brain stem is divided into three sub-regions the medulla oblongata is the most inferior part of the brain stem and is continuous with the spinal cord all communication between the higher brain regions and the spinal cord passes through the medulla oblongata the medulla oblongata regulates several autonomic functions that are critical for life these include nuclei that regulate breathing heart rate and blood pressure by regulating heart rate and blood pressure the medulla oblongata ensures that an adequate blood supply circulates throughout the body at all times other nuclei in the medulla oblongata are involved in coughing sneezing salivating swallowing gagging and vomiting several cranial nerves are associated with the medulla oblongata including the vestibule cochlear cranial nerve eight the glossopharyngeal cranial nerve nine the vagus nerve cranial nerve 10 the accessory nerve cranial nerve 11 and the hypoglossal nerve cranial nerve 12. lastly the medulla serves as the Communication Center that links the brain and spinal cord the pons is the bulging anterior sub-region in the middle of the brain stem that connects to the cerebellum pons is a Latin word meaning Bridge this name refers to the fact that the anterior part of the pons looks like a bridge that connects the two halves of the cerebellar hemispheres together the pons represents one of the major Pathways for information to travel from the brain and brain stem to the cerebellum it contains nuclei which regulate the rate and depth of breathing other nuclei in the pons help to regulate rapid eye movement or REM sleep this stage of sleep is characterized by random rapid movement of the eyes and Vivid dreaming the ponds houses sensory and motor cranial nerve nuclei for the trigeminal cranial nerve five abduces cranial nerve six facial cranial nerve seven and vestibular cochlear cranial nerve eight the midbrain is the superior sub-region that connects the brain stem to the diencephalon although it is a relatively small sub-region the midbrain contains a long list of nuclei tracts nerves and other structures let's focus on a few of the most prominent functions the midbrain integrates information from the cerebrum and cerebellum and plays a role in coordinating motor signals it contains auditory and visual reflex centers involved in the reflexive turning of the head and eyes in the direction of a sound the nuclei of the oculomotor nerve cranial nerve 3 and the trochlear nerve cranial nerve four originate in the midbrain these two cranial nerves control eye movements while there are several important anatomical landmarks of the midbrain we're going to focus on the most prominent external feature the corpora quadrigemina a series of four bumps on the posterior surface of the midbrain Corpus means body quad meaning four and Gemini means siblings these are the four sibling bodies the upper pair of bumps are known as the superior colliculi the Latin word colliculus means Mound these colliculi are involved in reflexes such as the Turning of the eyes and head in response to a visual stimulus for example the superior colliculi are at work when you see something move in your corner vision and turn suddenly towards the image the lower pair of bumps are known as the inferior colliculi they control reflexive turning of the head and eyes in the direction of a sound for example the inferior colliculi are at work when you hear a loud bait turns suddenly towards that noise the cerebellum is the second largest brain region cerebellum is Latin for little brain and it does look a bit like a smaller version of the cerebrum to understand the major functions of the cerebellum let's say there is a piece of cake on the table in front of you your cerebrum develops a plan to reach for the cake however the movement must be executed with the current position of the body in mind reaching for the cake when standing on two feet requires a different motor plan than if you were seated or if you were trying to balance on one foot also antagonists must be inhibited so that Prime movers and synergists can perform the movement when the cerebellum receives information about the motor plan from the cerebrum it incorporates what it knows about the position of the body and muscles Alters the motor plan and then sends the altered Clan back to the cerebrum to put it into action as you reach for the cake you will need to make hundreds of small corrections to guide your hand successfully towards the target your brain is receiving constant feedback about the position and speed of your Upper Limb and using this information to make Minor Adjustments to the movement as it occurs when the cerebellum detects a potential deviation from the route originally planned it processes the information and sends a modified plan back to the cerebrum the cerebellum is why our movement appears smooth precise and coordinated and why we're able to maintain our balance and posture the cerebellum also seems to be important to the learning of motor movements when we repeat a motor movement over and over again we gradually learn to execute it more smoothly and precisely when we look at the cerebellum we see that the surface is covered in folds of gray matter called Folia the white matter forms the inner region of the cerebellum and is called the Arbor Vitae Arbor means tree and Vitae means life this name refers to the tree-like shape of the white matter the importance of the cerebellum in facilitating smooth movement can especially be seen in someone who has experienced cerebellar damage look at the two MRIs on the right side of the screen the top MRI shows a normal healthy patient the cerebellum is circled in a red dotted line notice how the folds are visible and the Arborvitae the tree-like white matter on the inside is very clear and distinct now let's look at the bottom MRI this patient suffered a cerebellar infant a loss of blood flow to the cerebellum and this loss of blood flow led to the development of cerebellar ataxia Ataxia is the presence of abnormal uncoordinated movements in the next video that's about to play watch the patient closely while they can initiate movements without any difficulty their movements are jerky and uncoordinated this is due to the damage to their cerebellum and same thing you get here facing the chair turn in place and then sit no but reaching foreign YouTube the deal okay no you know what I found this is your 5K that's all right I didn't know to the left side at times so it's gone don't even need it