The basic structure of the brain
The human brain is not smooth (rats, mice and other animals have smooth brains) our brains are
always forming new neurons, so when it grows it starts to crunch up into folded spaces
It forms mountains and valleys. Valley’s are called sulci (or sulcus) unless they are incredibly
large, then they are called fissures. Mountains are guyri (or gyrus ).
The top of the brain is divided right in the center into two hemispheres. Right and left
The right hemisphere receives information from the left side of your body and controls the left.
The left hemisphere receives information from the right side of your body and controls the right.
Everything crosses over. The two hemispheres are divided by the longitudinal fissure or sulcus. They are connected to
each other. They are separated in the middle but, inside they are connected.
corpus callosum connects the two hemispheres.
o There are three main sulci
o 1. The longitudinal fissure: divides left and right
o 2. Central sulcus or central fissure: divides anterior and posterior (front and back)
frontal and parietal
o 3. Sylvian fissure of sulcus: or sometimes referred to as the lateral fissure. Separates the
The cerebral cortex is divided into four lobes.
o Frontal lobe
o Parietal lobe
o Occipital lobe
o Temporal lobe
o Within each lobe there are two types of cortex or tissue. Each portion of the cortex has
two different kind of tissue. They are known as primary cortex and associational cortex
The primary cortex is responsible for performing some basic input or output
function of that lobe. Ex. Hand burning, move hand.
Associational cortex: higher order functions. Higher than primary. It is more
complex. More recently evolved. It is the thought processing part of the brain.
The more evolved the organism, the higher the associational cortex. Ex. Frogs
only have the primary cortex. Brodmann mapped the brain.
He put numbers on the different areas of the brain.
Begins in the anterior portion and goes back to the central sulcus.
It’s primarily involved in motor control (muscle) what makes you move.
It also controls planning and inhibition of inappropriate behaviours
Not only planning how to move (primary) but also long term plans (association)
Inhibition of inappropriate behavior ex. Not going to tell my boss to shove it (association)
Brodmann 4, 6 is the primary area.
The central sulcus is a valley. So it has mountains around it (the precentral gyrus is right in front
of it) areas 4, 6- primary motor strip. Everything in front of it in the frontal lobe is associational. Motor Homunculus (little man)
If you see some with their face paralyzed on the right hand side…
o Their tumor is on the left
o Frontal lobe (cause they can’t move it)
o Motor: brodmanns 4,6
o Precentral gyrus
o It’s on the side, because the person can’t control their face.
Starts at the central sulcus and moves back until it hits the occipital lobe
Primary function is to receive information from the non specialized senses (somatosensory
sensory) basically from your body, generalized not eyes, ears.
Its primary strip is right behind the central sulcus: the postcentral gyrus. Primary strip in the
partiel cortex. Aside from the postcentral gyrus (primary) the rest of the parietal lobe is
Brodmann are- 3, 1, 2 (primary somatosensory strip)
The somatosensory strip also has a homunculus
o One slice is right infront of the other
o Very big on the sensory side ( ex. Genitals) Occipital lobe
In the poste