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Chapter 4

PSY 220 Chapter Notes - Chapter 4: Fourth Ventricle, Central Sulcus, Tegmentum


Department
Psychology
Course Code
PSY 220
Professor
Hurwitz Barry
Chapter
4

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PSY220- PSYCHOBIOLOGY
CHAPTER 4- ANATOMY OF THE NERVOUS SYSTEM
Main Ideas:
Each part of the nervous system has specialized functions. Damage to different
areas results in different behavioral deficits.
The cerebral cortex, the largest structure in the mammalian brain, elaborately
processes sensory information and provides fine control of movement.
As research has identified the different functions of different brain areas, a new
question has arisen: how do the areas work together to produce unified experience
and behavior?
It is difficult to conduct research on the functions of the nervous system.
Conclusions come from multiple methods and careful behavioral measurements.
Neuroanatomy- the anatomy of the nervous system
Terminology to Describe the Nervous System
Central nervous system (CNS):
Brain
o Hindbrain, midbrain, forebrain
Spinal cord
Peripheral Nervous System (PNS)- connects the brain and spinal cord to the rest of the
body; composed of the somatic nervous system and the autonomic nervous system
Somatic nervous system:
Controls voluntary muscles
Conveys sensory information to the CNS
Autonomic nervous system:
controls involuntary muscles (heart, intestines, etc)
a) Sympathetic- expends energy, prepares the organs for vigorous
activity
o “fight or flight” response
o increases breathing and heart rate, decreases digestive activity
o consists of chains of ganglia just to the left and right of the
spinal cord’s central regions
b) Parasympathetic- conserves energy
o facilitates vegetative, nonemergency responses
o decreases heart rate, increases digestive activity
o consists of the cranial nerves and nerves from the sacral spinal
cord

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Anatomical Terms Referring to Directions:
Dorsal- toward the back, away from the ventral (stomach) side
*The top of the brain is considered dorsal because it has that position in four-legged
animals
Ventral- toward the stomach, away from the dorsal (back) side
*a ventriloquist is a “stomach talker”
Anterior- toward the front end
Posterior toward the rear end
Superior- above another part
Inferior- below another part
Lateral- toward the side, away from the midline
Medial- toward the midline, away from the side
Proximal- located close (approximate) to the point of origin or attachment
Distal- located more distant from the point of origin or attachment
Ipsilateral- on the same side of the body (ex. two parts on the left or two
on the right)
Contralateral- on the opposite side of the body (one on the left & one on
the right)
Coronal plane- a plane that shows brain structures as seen from the front
(or frontal plane)
Sagittal plane- a plane that shows brain structures as seen from the side
(sagittal, side)
Horizontal plane- a plane that shows brain structures as seen from above
(or transverse plane)
The Spinal Cord
Spinal cord- the part of the CNS within the spinal column; it communicates with all the
sense organs and muscles except those of the head
The spinal cord is segmented, and each segment has on each side a sensory nerve and a
motor nerve.
Gray matter- H-shaped center of the brain & spinal cord, densely packed with cell
bodies & dendrites
White matter- consists mainly of myelinated axons
If the spinal cord is cut at a given segment, the brain loses sensation from that segment
and below as well as motor control over all parts of the body served by that segment and
the lower ones.

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Bell-Magendie law- the entering dorsal roots of the spinal cord (axon bundles) carry
sensory information, and the exiting ventral roots carry motor information
The axons to and from the skin and muscles are the peripheral nervous system.
The cell bodies of the sensory neurons are in clusters of neurons outside the spinal cord,
called the dorsal-root ganglia.
Lamina- a row or layer of cell bodies separated from other cell bodies by a layer of
axons and dendrites
Column- a set of cells perpendicular to the surface of the cortex with similar properties
Tract- a set of axons within the CNS, also known as a projection; if axons extend from
cell bodies in structure A to synapses onto B, we say that the fibers “project” from A onto
B
Nerve- a set of axons in the periphery, either from the CNS to a muscle or gland or from
a sensory organ to the CNS
Nucleus- a cluster of neuron cell bodies within the CNS
Ganglion- a cluster of neuron cell bodies, usually outside the CNS (as in the sympathetic
nervous system)
Gyrus- a protuberance (lump) on the surface of the brain
Sulcus- a fold or groove that separates one gyrus from another
Fissure- a long, seep sulcus
Major Divisions of the Vertebrate Brain
Forebrain- most prominent part of the mammalian brain
consists of two cerebral hemispheres that
a) receive sensory information, mostly from the contralateral
(opposite) side of the body
b) control muscles mostly on the contralateral side by way of axons to
the spinal cord and the cranial nerve nuclei
The outer portion is the cerebral cortex (“brain shell”)
Under the cerebral cortex are other structures including
o The thalamus- processes sensory information & sends output
to the cerebral cortex
o The hypothalamus- small structure that conveys messages to
the pituitary gland, altering its release of hormones
o Pituitary gland- synthesizes hormones that the blood carries to
organs throughout the body
o Basal ganglia- critical for movement, learning & remembering
how to do something, attention, language, planning, & other
cognitive functions
o Nucleus basalis- receives input from the hypothalamus and
basal ganglia & sends axons that release acetylcholine to
widespread areas in the cerebral cortex; arousal, wakefulness,
attention
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