Introduction to the Central Nervous System - UBC Neuroanatomy Season 1 - Ep 1

the adult human brain weighs approximately one and a half kilograms making up less than 2% of the person's body weight and yet it defines our humanity and makes us the individuals that we are the brain is responsible for the generation of language and thought attention consciousness memory and imagination in order to fit into the skull and accommodate the massive number of neurons and connections needed the brain is highly folded this results in the creation of gyri or ridges and sulci or furrows if we were to unfold the entire human brain it would take up approximately one square metre perhaps the most impressive feature of the brain is the amount of connections formed between neurons there are an estimated 86 billion neurons in the brain each of which forms an average of 7,000 connections with other neurons resulting in between 100 and 500 trillion synapses within the brain in an attempt to conceive of the enormity of this system the number of neurons in the human brain has been equated to the number of stars in the Milky Way now that we have begun to appreciate the complexity of the human brain let's begin to examine its structure the brain can be divided into functional and anatomical regions we will now start with an anatomical overview to establish a common terminology and to describe the areas of the brain the brain has multiple surfaces here we have the superior surface and this here is the inferior surface there are also anterior and posterior aspects to the brain here's a section through the brain within the skull and we can appreciate the axis within the CNS connections can travel either towards the anterior pole here or towards the inferior end of the spinal cord fibers can move either rostra Li towards the rostral pole or caudally towards the caudal pole now let's look at these component parts of the brain this is the forebrain which is composed of the cerebral hemispheres and deep structures the right and left hemispheres are roughly symmetrical and are connected through corpus callosum which you can see here here we have cut the brain in half separating the two hemispheres from each other this is the cut surface of corpus callosum the largest white matter tract in the brain impressively it consists of an estimated 200 to 250 million projections this structure here is the thalamus and together with the hypothalamus here and the sub thalamus which you cannot see it makes up the diencephalon the cerebral hemispheres and the diencephalon together comprise the forebrain we now move into the brain stem which is caudal to the diencephalon the brainstem can into three parts the midbrain located here just caudal to the thalamus contains the large fiber bundles with cerebral peduncles that connect the forebrain with all caudal structures the pons is located caudal to the midbrain it is connected to the cerebellum through the cerebellar peduncles the most caudal part of the brainstem is the medulla it is continuous with the spinal cord as it exits through foramen magnum of the skull the cerebellum is embryologically part of the pons but its functions are so distinct that it is now considered its own entity separate from the brainstem the cerebral hemispheres can be divided into lobes along some key surface landmarks the central sulcus separates the frontal lobe from the parietal lobe the lateral fissure separates the temporal lobe from both the frontal and parietal lobes the occipital lobe is separated from the parietal lobe via the parietal occipital sulcus which you can see on this medial aspect of the brain you can draw a line onto the lateral surface right here to differentiate between the occipital lobe and the parietal and temporal lobes in this medial view of the brain you can identify a continuous strip of cortex which swings around the surface of the brain this lobe has been dubbed the limbic lobe due to its intimate relationship with the limbic system it spans the frontal parietal and temporal lobes deep within the brain our space is filled with cerebrospinal fluid or CSF this is a 3d reconstruction of the ventricular system you can see the two C shaped lateral ventricles in the cerebral hemispheres they have an anterior horn deep within the frontal and parietal lobes of the forebrain a posterior horn which extends into the occipital lobe and an inferior horn which extends into the temporal lobe these lateral ventricles are connected to the third ventricle in the midline the third ventricle is connected to the fourth ventricle through the cerebral aqueduct on this mid sagittal section of the brain we can identify different components of the ventricular system this here is the lateral ventricle the anterior horn will extend anteriorly here into the frontal lobe and the posterior horn will extend into the occipital lobe this here is the third ventricle the thalamus is on either side of the third ventricle the third ventricle connects to the fourth ventricle via the cerebral aqueduct right here this here is the fourth ventricle at the level of the pons and medulla the fourth ventricle is going to close off into the central canal let's look at the various planes a brain can be sectioned in this is a very important concept because imaging of the brain uses these planes I'm going to cut this brain in the coronal plane so you can now see corpus callosum here and we've started to look into the ventricular system so this is the anterior tip of the anterior horn here so this next slice will take us into the anterior pull of the temporal lobe right here those pieces might fall off because they're not connected to the plane that I'm cutting in there we go let's have a look at that alright so what you can see on this slide is really the lateral ventricle again you've got the head of the caudate nucleus right there and the putamen here this is the anterior limb of the internal capsule alright so in this section now you can see the two lateral ventricles as well as the third ventricle here on either side of the thalamus all right so here in this section now you can again see the two lateral ventricles you are going into the cerebral aqueduct on our way to the fourth ventricle this here is the inferior horn of the lateral ventricle okay so in this section here again here are the two lateral ventricles here again is the inferior horn the hippocampus right there in the floor of the inferior horn all of this here is the thalamus where quite posterior now as you can tell in the brain so all of this is the Loomis here we're actually getting into the posterior parts of the thalamus there right here we are in the midbrain and the pawn so it's a bit of an oblique section here through the brainstem but you can see the cerebral aqueduct here and of course this is the pons alright so in this section here you can see that we're now getting into the posterior horn of the lateral ventricle this is the very very tail end of corpus callosum there you can see the cut surface here of the cerebellum it's the middle cerebellar peduncle moving in there and here you can see the central canal who's going to open up into the fourth ventricle which will light just on the other side of that opening there in this coronal section we can see both gray and white matter white matter is the sum of all myelinated axons or tracts as they travel through the CNS gray matter is the sum of all nerve cell bodies it can be seen here along this cortical band on the surface of the brain which is why an increased surface area is so important to accommodate the large number of neurons in the cortex gray matter can also be found in these deep nuclei of the forebrain including basal ganglia and limbic structures we're going to cut this brain in a horizontal orientation they were now going to cut through the brainstem here in an axial orientation so here's the midbrain here we've cut through the pons in the superior cerebellar peduncle as it projects to the cerebellum so this is the last section here through the pons and you can see some of the deep cerebellar nuclei here this cut here you can see the inferior part of the cerebellum and then part of the open medulla and here you can see the closed medulla as the ventricle has closed over the central canal here finally the brain can be cut along the sagittal plane here we have cut the brain along the mid sagittal plane to separate the two hemispheres with this overview we now have a common terminology as we begin our journey through the brain you

Channel: UBC Medicine - Educational Media

Views: 1,131,154

Rating: 4.9477439 out of 5

Keywords: Neuroanatomy (Anatomical Structure), Central Nervous System, UBC, University of British Columbia, Faculty of Medicine, MedIT, Educational Technology, Claudia Krebs, Zachary Rothman, Canada, Vancouver, BC, Medicine, Anatomy, Dissection (Taxonomy Subject), Gross Anatomy Laboratory, Flexible Learning, 4K, Toby Gorman, richard neufeld, echocloud, gloo studios, gloostudios, james wallace

Id: xB7rXw_3gVY

Length: 14min 47sec (887 seconds)

Published: Mon Jan 13 2014

Reddit Comments

[u/jjc89]

I’ve just been studying this stuff today so this will make an interesting watch! Thanks!

[u/JohnyyBanana]

Ive been going over this series the past 2 days, its one of the best things ive found on youtube ever! Such a high quality production!