The Central Nervous
System
Part A
Human Anatomy & Physiology, Sixth Edition
Elaine N. Marieb
12
Development of Neurons
 nervous system originates from neural tube & neural
crest
 CNS from neural tube
 PNS from neural crest cells
 three-phase process of neural development:
 Proliferation of neural cells
 Migration
 Differentiation of neuroblasts
Guiding Axonal Growth
 Scaffold of glial fibers & ECM
 Attractants released by target cells
 Release of NGF by astrocytes
 Neurotrophins released by other neurons
 Interactions of repulsive guiding molecules
Embryonic Development: Week 1
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Fertilization
Movement to uterus
Implantation
Blastocyst formation
Blastocyst & Gastrulation
Neurulation: Specialization of Ectoderm
Figure 28.9a, b
Neurulation
Figure 28.9c,d
Neural Tube & Primary Brain Regions
Week 3
Neural Tube & Primary Brain Regions
Week 3
Week 4
Neural Tube & Primary Brain Regions
LV
LV
3rd
4th
Week 3
Week 4
Week 5
Brain Development
Figure 12.3
Ventricles of the Brain
 Ventricles are filled with cerebrospinal fluid
 Fluid moved by ciliary motion of ependymal cells
Figure 12.5
Basic Pattern of the Central Nervous System
 Spinal Cord
 Core - gray matter – soma
 Edges - white matter myelinated axon tracts
 Brain
 Highly convoluted
 Cortex & nuclei - areas with
mostly neuron soma
 White mater organized tracts
of axons
Anatomical Features of the Cerebral Cortex
 Sulcus (pl sulci)
 Groove resulting from folding of neural tissue
 Deep sulci (fissures) divide the hemispheres into
lobes
 Lobe
 Region of the cerebrum
 Frontal, parietal, temporal, occipital, & insula
 Gyrus (pl gyri)
 Bulging region between shallow sulci
Cerebral Cortex Anatomy
Cerebral Cortex
 Gray matter on the surface of the cerebrum
 Location of motor, sensory & association neuron cell bodies
Grey matter
sulcus
gyrus
White matter
Cerebral White Matter
 Myelinated fibers & their tracts
 Communication between cortex & lower CNS center, &
areas of the cortex
 Commissures
 Association fibers
 Projection fibers
Functional Areas of the Cerebral Cortex
Motor
Sensory
Cognition
Primary Motor Cortex
 Precentral gyrus
 Conscious control of
voluntary movements
 Pyramidal cells
 axons form corticospinal
tracts
Premotor Cortex
 Anterior to precentral gyrus
 Coordinates learned actions
 Plans of movements
Broca’s Area
 More developed in one hemisphere (usually the left)
 Directs muscles involved in speech
 Active as one prepares to speak
Frontal Eye Field
 Controls voluntary eye movement
Primary Somatosensory Cortex
 Located in the postcentral gyrus
 Receives information from the skin
& skeletal muscles
 Exhibits spatial discrimination
Somatosensory Association Cortex
 Integrates sensory information
 Comprehensive understanding of the stimulus
Visual Areas
 Primary visual cortex
 Posterior occipital
lobe & in calcarine
sulcus
 Receives visual info
from retina
 Visual association area
 Surrounds primary visual cortex
 Interprets visual stimuli
Auditory Areas
 Primary auditory cortex
 Superior margin of
temporal lobe
 Pitch, rhythm, &
loudness info
 Auditory association area
 Posterior to the primary auditory cortex
 Stores memories of sounds & permits perception of sounds
 Wernicke’s area
 Integrating sound & speech
Olfaction
Association & Interpretation Areas
Figure 12.8a
Proposed Memory Circuits
Figure 12.22
Lateralization of Cortical Function
 Lateralization
 Unique functions of each hemisphere
 Left hemisphere
 language, math, & logic
 Right hemisphere
 visual-spatial skills, emotion, & artistic skills
 Cerebral dominance
 Hemisphere dominant for language (left)