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Chapter 2 Biological Foundations of Behavior
when a gust of wind sent particles of debris hurtling toward your eyeballs. By
saving the many milliseconds it would take to send a message to your brain, have
it interpreted, and have a command sent back along the spinal highway to motor neurons, spinal reflexes can spell the difference between a minor injury and
a serious one.
The Brain: Your Crowning Glory
Concept 2.16
The brain is divided into three major
parts: the hindbrain, the midbrain, and
the forebrain.
We begin our tour of the brain at the lowest level, the hindbrain — the part of the
brain where the spinal cord enters the skull and widens. We then work our way
upward, first to the midbrain, which lies above the hindbrain, and then to the
forebrain, which lies in the highest part of the brain. Concept Chart 2.3 shows
these major brain structures.
The Hindbrain The lowest part of the brain, the hindbrain, is also the oldest
part in evolutionary terms. The hindbrain includes the medulla, pons, and cerebellum. These structures control such basic life-support functions as breathing and
heart rate.
The medulla and pons contain sensory neurons that transmit information
from the spinal cord to the forebrain. The medulla is the section of the hindbrain
that lies closest to the spinal cord. It forms the marrow, or core, of the brainstem,
CONCEPT CHART 2.3
Major Structures of the Human Brain
Forebrain
Cerebral Cortex
Higher mental functions
including thinking, language,
learning, memory, emotions, and
control of voluntary movement
Hindbrain
Pons
Conveying sensory
information from the
spinal cord to the
forebrain; regulation
of states of wakefulness
and sleep
Corpus Callosum
Bundle of nerve fibers
that connect the two
cerebral hemispheres
Thalamus
Relay station for sorting
and integrating sensory
input; regulation
of sleep-wake cycles
Limbic System
Emotional processing, motivated
behavior, and learning and
memory functioning; consists
of amygdala, hippocampus,
parts of the hypothalamus and
thalamus, and nearby structures
Basal Ganglia
Regulation of
movement and
coordination
Cerebellum
Regulation of
balance and
coordination
Midbrain
Reticular Formation
Regulation of attentional
processes and states of
alertness and arousal
Spinal
cord
Medulla
Conveying sensory
information from the
spinal cord to the
forebrain; control of
basic bodily processes
including heart rate
and breathing and
certain reflexes