The Nervous System
And Brain Organization
Central Nervous System
• Consists of the brain and spinal cord
• The brain is the central “computer” of the
nervous system
• The spinal cord is the “cable” that is used to
communicate to the rest of the body
Peripheral Nervous System
• All the parts of the nervous system outside of
the brain and spinal cord
• Two major divisions
– Somatic system – the muscles and sense
organs (voluntary behavior)
– Autonomic system – the internal organs and
glands (involuntary behavior)
Autonomic Nervous System
• Two divisions
– Sympathetic branch – arouses the body
• Prepares the body for fight or flight
– Parasympathetic branch – quiets the body
or brings it back to normal
Nervous System
Central
Nervous
System
Brain
Peripheral
Nervous
System
Spinal
Cord
Autonomic
System
Sympathetic
System
Somatic
System
Parasympathetic
System
Brain Organization
• Cerebrum – two large hemispheres that
cover the upper part of the brain
• Cerebral cortex – the outer layer of the
cerebrum
– made up of wrinkled gray matter that contains
nerve cell bodies
Brain Organization cont’d…
• Cerebral hemispheres – right and left halves
of the cerebrum
• Corpus callosum – bundle of fibers
connecting the hemispheres
– Cut in a ‘split-brain’ operation
• Spatial neglect – when a person pays no
attention to the left side of visual space after
damage to the right hemisphere
Lobes of the Cerebral Cortex
• Lobes – areas on the cortex defined by
major fissures or functions
• Occipital lobe – vision
• Parietal lobe – bodily sensations (touch,
temperature, pressure)
Lobes of the Cerebral Cortex
• Temporal lobes – language (on the left only)
and hearing
• Frontal lobes – motor control, speech,
abstract thought
• Association cortex – all areas of the cerebral
cortex not primarily sensory or motor in
function – complex skills like language,
memory, recognition, and problem solving
Parietal lobe
Frontal
lobe
Occipital
lobe
Temporal
lobe
Cerebellum
Association Cortex
• Broca’s area – language area – grammar and
pronunciation – left frontal lobe
• Aphasia – speech disturbance related to
brain damage
• Wernicke’s area – language comprehension
– left temporal lobe
• Agnosia – inability to identify seen objects
Subcortex
• Subcortex - all brain structures below the
cerebral hemispheres
• Divided into three parts
– Brainstem (or hindbrain)
– Midbrain
– Forebrain
The Brainstem
• Also known as the hindbrain
• Lowest portions of the brain
• Contains the cerebellum, medulla and pons
• Cerebellum – controls posture, muscle tone
and coordination – stores memories related to
skills and habits
• Medulla – connects brain to spinal cord –
controls vital life functions such as heart rate,
breathing, swallowing, etc.
• Pons – bridge between medulla and other
structures – influences sleep and arousal
The Midbrain
• Small region, located above spinal cord, but
below the forebrain
• Coordinates simple muscle movements with
sensory information
• Reticular formation – network of fibers and
cell bodies throughout the hindbrain –
associated with attention, alertness and
some reflexes
The Forebrain
• Contains the thalamus and hypothalamus
• Thalamus – located on top of brain stem –
relays sensory information to the cerebral
cortex
• Hypothalamus – controls metabolic
functions including body temp, libido,
hunger, thirst, and the endocrine system
Pituitary
Hypothalamus
The Limbic System
• Contains hypothalamus, parts of the
thalamus, amygdala, and hippocampus
• Large role in producing emotion and
motivated behavior
• Amygdala – associated with fear responses
• Hippocampus – associated with storing
memories (lies in the temporal lobe)
Amygdala
Temporal
lobe
Hippocampus