The Central
Nervous System:
The Brain and
Spinal Cord
Chapters 13 & 14
BRAIN
The Brain
• 100 billion neurons
• 1.6 kg in males/1.45 kg in females
(size is not representative of
intelligence, only overall average
body size)
• Complexity dictates processing
power
Major Subdivisions of the Brain
1. Cerebrum
2. Cerebellum
3. Diencephalon
– thalamus
– hypothalamus
4. Brain stem
– midbrain
– pons
– medulla oblongata
Fig. 14-2
No functional area of the brain
works alone
~ 80% of the brain’s mass; the
thinking center
1. Cerebrum
2 cerebral hemispheres contain 4
distinct lobes:
• Frontal – motor cortex
• Parietal – sensory cortex
• Occipital – visual cortex
• Temporal – auditory &
olfactory cortex
Fig. 14-8
Each hemisphere primarily
controls the opposite side of
the body
2. Cerebellum
• Coordination of
movement
• Balance and
posture
Thalamus - receives
sensory inputs and
determines which of
these signals to forward
to the cerebral cortex
Hypothalamus - regulates
the pituitary gland, body
T, food intake, emotion,
sleep-wake cycle and
memory; controls
autonomic functions
(heart rate, respiration,
blood pressure)
3. Diencephalon
(INTERBRAIN)
Limbic System
• The “emotional”
center, important for
perception of pleasure
and pain & functions
in memory formation
• Includes
hypothalamus,
hippocampus (longterm memory
formation), amygdala
(processing of
emotions)
Midbrain – processing of
visual & auditory data
Pons – contains
respiratory center
Medulla oblongata –
relays sensory info to
thalamus & other parts
of brainstem; controls
cardiovascular,
respiratory and digestive
activities
4. Brainstem
lowest part of the brain
where it connects to the
spinal cord
Protection of the Brain
Several different mechanisms:
• Skull & scalp hair
• Meninges (connective tissue membranes wrapping
the CNS)
• Cerebrospinal fluid (CSF) cushions and nourishes
the brain
• Blood-brain barrier - separation of the CNS from
general circulation; composed of the least permeable
capillaries; helps to maintain homeostasis in the brain
SPINAL
CORD
Spinal Cord
• Connects the brain & PNS
• Located within the
vertebral column
• From brain stem through
foramen magnum to
second lumbar vertebra
(L2), ends as “horse tail”cauda equina