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I want to talk to you a little bit about the frontal lobe,

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which is the behavioral personality

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and also the inhibitory area of the brain.

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It's responsible for impulse control.

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And let's start out at the level of the Sylvian fissure,

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which looks a little bit like a centipede or a caterpillar.

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Right there.

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They're the antennae of the caterpillar.

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You see the body of the caterpillar going back.

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And here's the tail.

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Now just above that,

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we've got the inferior frontal gyrus

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and the inferior frontal sulcus.

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Now, if there's an inferior one,

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there must be a superior one, right?

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Well, here's the inferior one.

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Let's draw over it. Inferior frontal sulcus.

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And if we kept going and we scrolled inward,

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and we weren't volume averaging

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against the direction of the sulcus,

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we would see another one, the middle sulcus,

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and then another one above that, the superior sulcus.

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We'll see these in the coronal projection much better.

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Now, sometimes the middle one is divided up into two parts.

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There are two sulci creating a couple of lobes of the

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middle component or the middle gyrus of the frontal lobe.

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But I'm going to focus on the inferior

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portion of the frontal lobe,

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namely the inferior sulcus and the inferior gyrus.

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Just below it is going to be the Sylvian fissure.

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And just below that is the temporal lobe.

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So, we are dividing up the frontal lobe from the temporal lobe.

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To find the entire temporal lobe,

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you've got to go up and back to

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the central sulcus of Rolando.

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Now, I'm going to help you find the central

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sulcus of Rolando right now.

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So, let's take the inferior frontal sulcus

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and follow it back.

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And here's this staircase descending structure.

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Often these two don't communicate with each other.

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But here you see it kind of descending

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like a little staircase right here.

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And right behind it is the precentral gyrus.

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So precentral sulcus pointed to by this structure.

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Precentral gyrus.

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Yes, there is a little small sulcus inside that.

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The precentral gyrus is always going to be bigger

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than the postcentral gyrus.

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The precentral gyrus and the postcentral gyrus

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are separated by the central sulcus of Rolando.

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The central sulcus of Rolando, up and back,

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separates the frontal lobe from the parietal lobe.

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There's some of the parietal occipital sulcus separating

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the parietal lobe from the occipital lobe.

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Now, let's go back to the frontal lobe.

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And if we look very carefully,

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we have created, along the top of these antenna,

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here is the anterior horizontal ramus

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and anterior ascending ramus of the Sylvian fissure.

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Right above that, the letter M.

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I'm going to draw the M right here

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just so you can see it.

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Here is M,

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or maybe a heart,

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if you want to have extreme imagination.

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And that is the area known as Broca's area,

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specifically in the back.

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Now, the front part is called the pars orbitalis.

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It's going to abutt the orbital gyri.

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This is Brodmann 47.

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The pars triangularis,

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yes, it is triangular, well-named in the middle,

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Brodmann 45.

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The pars opercularis, or opercula,

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is in the back,

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which is the start of the frontal operculum.

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This is Brodmann 44.

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Officially, Brodmann 44 and Brodmann 45,

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in the dominant hemisphere,

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which is usually on the left side,

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forms Broca's area.

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Now, let's go back to the central sulcus for a minute.

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Here it is.

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Here's the central sulcus.

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And work our way towards the midline.

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You're going to see how hard it is to follow

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it continuously all the way back.

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We're still following it. We're still following it.

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And we've got it.

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It's this little oblique slit that is found just

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anterior to this structure right here,

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which is composed of the cingulate sulcus and the

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supramarginal or marginal sulcus.

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Right here.

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So once you find this long,

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stringy sulcus that goes into the cingulum.

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Right in front of that,

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the oblique dark area seen anterior to it

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is the central sulcus of Rolando in the midline.