Central Nervous System:
The Brain and
Spinal Cord
The Nervous System
Option E
The Brain

Most developed/complex organ of the
body.

Cephalization
4 Major Regions
1.
2.
3.
4.
Cerebral Hemispheres
Diencephalon
1. Thalamus
2. Hypothalamus
3. Epithalamus
Brain Stem
1. Midbrain
2. Pons
3. Medulla
Cerebellum
Cerebrum
Diencephalon
Brain stem
Cerebellum
4
Gray Matter
Unmyelinated fibers
Concentrated area of
neuron cell bodies
Found:
Outer Cortex
Surrounding Central
Canal
Scattered w/White
Matter
vs. White Matter
Myelinated fibers
Found:
Between gray matter
layers
Ventricles
Hollow chambers within the brain
 Flow into Central Canal
 Filled with Cerebrospinal Fluid (CSF)
 Divided into Segments:

 Lateral
Ventricles  in cerebral hemispheres
 Third Ventricle  in diencephalon
 Fourth Ventricle  in pons / medulla
Lateral
ventricles
Third
ventricle
Fourth
ventricle
8
1. CEREBRAL HEMISPHERES
Most superior, largest part (83%)
 elevated ridges gyri (gyrus)
 shallow grooves sulci (sulcus)
 deep grooves fissures
 longitudinal fissure—btwn. hemispheres
 transverse fissure– btwn. cerebrum
and cerebellum

Are the Hemispheres Connected?
CORPUS
CALLOSUM
Cerebrum Divided into
5 Major LOBES
Frontal Lobe
 Parietal Lobe
 Temporal Lobe
 Occipital Lobe
 Insula

Central
sulcus
Precentral
gyrus
Postcentral
gyrus
Frontal
lobe
Parietal lobe
Occipital
lobe
Temporal lobe
18

INSULA
Cerebral Hemispheres divided into
3 REGIONS
1.
Cerebral Cortex
2.
Cerebral White Matter
Cerebral Basal Nuclei
3.
The Cerebral Cortex
Area of consciousness
 Composed of gray matter
 All interneurons !
 No functional area acts alone!

3 areas of Cerebral Cortex
1.
2.
3.
•
•
Motor Area
Sensory Area
Association Area
Don’t confuse w/ Motor, Sensory
Neurons!
Areas detected by modern imaging
techniques
Motor Area of Cerebral Cortex
Located in precentral gyrus
 Controls all voluntary movements
 Subdivided into:

 Premotor
cortex
 Primary motor cortex
 Broca’s region

Premotor cortex
 Located
anterior to precentral gyrus
 Controls LEARNED, repetitive skills!
 Musical
instrument playing
 Keyboarding, writing

Broca’s Region
 Located
anteriorly/inferiorly to premotor
cortex
 Left hemisphere only
 Controls MOTOR SPEECH
 Talking!

Primary Motor Cortex
 Controls
voluntary movement of skeletal
muscles!
 Precise motor control regions dominant here!
Homunculus
Sensory Area of Cerebral Cortex
Located in postcentral gyrus
 Controls all sensation capabilities
 Subdivided into:
1. Somatosensory cortex
2. Association cortex
3. Visual cortex
4. Auditory cortex
5. Olfactory cortex
6. Gustatory cortex
7. Vestibular cortex

SOMATOSENSORY
CORTEX
Controls tactile
sensations in skin and
skeletal muscles
What part of the body is
most sensitive to
touch?
ASSOCIATION
CORTEX
Receives information
from somatosensory
cortex
Allows for
understanding of
tactile sensations!
VISUAL
CORTEX
Receives information
from eyes
Segments allow for:
identification of
images
location/position of
images
AUDITORY
CORTEX
Receives information
from ears
Allows for identification
of sounds
OLFACTORY
CORTEX
Receives information
from smell receptors
Allows for identification
of SCENTS
GUSTATORY
CORTEX
Receives information
from the tongue
Allows for identification
of TASTES
VESTIBULAR
CORTEX
Receives information
from inner ear
Allows for maintenance
of BALANCE
Prefrontal
Cortex
Controls intellect,
learning, personality,
abstract thinking,
judgement,
reasoning, planning,
compassion,
conscience, moral
thought, etc.
Develops slowly…
Linked to Limbic System
WERNICKE’S
REGION
Understanding
spoken/written
language
Reminder:
What region allows for
ability to speak?
VISCERAL
AREA
Perception of internal
body sensations:
full bladder
nausea, etc.