[Music] what is eloquent well you know you could argue that all parts of the brain are important which is true but the truth is that there's a great deal of redundancy and i'm sure dr lewis is going to talk much more about this but you know there's there are certain areas of the brain whose function really can't be reproduced uh and that are very sensitive to to damage so the main areas that we talk about are the motor cortex so the motor cortex is the primary motor cortex is located um in the pre-central gyrus so this is this is the side view of the brain this is the cerebellum um this is the temporal lobe this is the frontal lobe this is the central sulcus that divides the frontal lobe from the parietal lobe this is the occipital lobe uh the central sulcus in front of the central sulcus we find primary motor cortex that's where all of the primary motor neurons are and then behind central sulcus we find the primary somatosensory cortex which is where all of the primary sensory cortex is and it this cortex then sends tracks down through the internal capsule um through the brainstem and that forms the motor tracks that we all together consider you know eloquent motor function there is there are these areas right in front this pre-motor area there's an area in the sort of middle um immediately just in front of this primary motor cortex we call that the supplementary motor area that can actually be really important it helps patients initiate movement and so sometimes even if this area even if the motor area is normal if this area is damaged patients may not be able to move it may look like they have a stroke because they they can't connect the desire to move with the ability to move generally that area though has redundancy and it recovers function if damaged typically over a period of weeks to months at the most so speech so speech is almost always lateralized you know in right-handed people which is the majority of people speech is almost always on the left side interestingly you know even in left-handed people about 50 of the time speech is also on the left side so we're really talking about a vast majority of people for whom um the left brain is dominant so in the left brain in the or in the dominant hemisphere um if it happens to be right for a left-handed person we talk about a few major speech areas so the first one is broca's area that's our our uh motor speech area this is located specifically in the frontal curriculum so this is in the inferior frontal gyrus so it's the sort of bottom of the frontal lobe and the the correlate to the motor speech area is wernicke's area so wernicke's area is well you know some people refer to as a sensory speech area this is um while roca's area a deficit there is going to give you problems with producing speech but you generally have a good ability to understand speech in wernicke's area the reception of speech is really affected and patients can talk but they they may they have what we call a fluent aphasia which is that they're saying words but they're just not making sense you know between those the speech track is what we call the the arcuate fasciculus um and that tract is you know connects the motor speakers to the sensory areas among other things and damage anywhere along there can cause any degree of aphasia from a partial aphasia to what we call a global aphasia which is a complete inability to to speak to either understand or produce language so speech is really one of the you know it's the thing that we paid by far the most attention to um you know and then second would be would be motor but speech is really a very sensitive function that is very difficult to get back so we are very careful uh for any lesions that are near speech areas um in terms of memory memory you know typically the dominant side hippocampus is is very heavily involved with memory um but there are instances where where that is not not the case particularly in patients with long-standing seizures and things like that so the visual cortex is considered eloquent so the primary visual cortex um the occipital lobe is is the primary visual cortex and then the optic radiations which is connecting all of the optic tracts starting from the optic nerves and the optic chiasm going back into the optic radiations and coming back down into the visual cortex so you know we have to sort of have a really good 3d sense of where everything is um in this complex space because yes your occipital lobe is here but you know you could be near the ventricle for example and that's actually where um some of your optic radiations are and so you have to know in any given area what track not only what cortex is near you but what tracks are near you [Music] hey everyone ryan rad here from neurosurgerytraining.org if you like that video subscribe and donate to keep our content available for medical students across the world