Intro to the Brain

Nervous System Organization

Remember that it is all about the CNSComposed of the brain and spinal cord; integrates and processes information.  when it comes to the nervous systemThe organ system that controls body functions using electrical and chemical signals.. Sensory information can come from somatic tissues such as the skinThe body’s largest organ, providing protection and regulation. or visceral tissues such as your liverA large organ that produces bile, detoxifies blood, and stores nutrients..  Motor output can go to either somatic or visceral tissues as well. Within visceral tissues, there are two more divisions.  The sympathetic divisionPart of the autonomic nervous system that prepares the body for stress and activity. is called the fight or flight response whereas the parasympathetic divisionPart of the autonomic nervous system that conserves energy and promotes rest-and-digest functions. is the rest and digest division.  These two are constantly fighting each other much as I and my brother did for ummmm…allllllllllllllllll of my childhood.

Sectioning the Brain

You need to start looking at pictures of the brain.  You must recognize different types of sections. These are created by the frontalForehead bone; forms the front part of the skull and roof of the orbits. Smooth and curved., transverse, and sagittal sections you see above.  Most students are quite skilled at identifying a sagittal section A cut or slice of the body or an organ for study.. This type of section cuts the brain into a left and right section.  This will be the most common section we use.  However, in the lab, we will use frontal and transverse pictures, which are much more difficult to discern.  Before we are done with the brain, you will have a feel for the anatomyThe study of the structure of the human body. produced by these sections.  Usually the ventricles, or open spaces and the choroid plexuses, or blood capillary networks, are landmarks for these sections.  Take a look yourself at the section on the left and the middle section.  Try to find the open spaces and/or the choroid plexuses.

Neuroanatomical Terms

When we talk about the brain, we have specialized terminology.  We’ve been using ventralRelating to the front or belly side of the body. and dorsalRelating to the back side of the body. when referring to the spinal cordThe central nervous system structure that relays signals between the brain and body.. However, when we refer to the brain, we use rostral and caudal.  Rostral means front and caudal means tail.  Look at how this complicates the application of dorsal and ventral.  The dorsal surface of the brain becomes the superiorAbove or toward the upper part of the body. surface and ventral becomes inferiorBelow or toward the lower part of the body..  I want you to think of a four-legged animal because these terms come from studying them, not bipedal humans. 

The other thing that should be noted is that frontal sections of the brain are usually called coronal sections.  This is because a frontal section of the brain is a cut along the same axisSecond cervical vertebra; has the odontoid process (dens) for pivoting head (“no” motion). as the coronal sutureRuns across top of skull between frontal and parietal bones (like a headband)..

Major Brain Areas

We are going to define and then describe 6 main areas of the brain.  The cerebrumThe largest part of the brain, responsible for thought, memory, and voluntary movements. is the big brain hat.  We will cover this last, once you’ve been thoroughly exhausted by the rest of it.  The cerebellumThe brain region responsible for balance, coordination, and fine motor control. is the little brain. It is caudal and ventral on the brain, or at the back and below the cerebrum. The diencephalonA brain region that includes the thalamus, hypothalamus, and epithalamus. is this internal area here. It contains many important structures we cover here and use often next semester.  The last three major brain areas all belong to what is called the brain stem.  Or, at least, that’s what we called it when I was in school in the 1990s.  Science has obviously progressed since then. Now, we treat these as distinct areas of the brain stem: the midbrainThe upper portion of the brainstem involved in visual and auditory processing., the ponsA part of the brainstem that connects the cerebrum to the cerebellum and helps regulate breathing., and the medulla oblongataThe lowest part of the brainstem controlling vital functions like breathing and heart rate..  That is their sequence dorsal (top) to ventral (bottom).