Download Central Nervous System

Central Nervous System
The CNS is made up of the spinal
cord and brain
The Meninges
 Special covering membranes, the
meninges, protect and support the
spinal cord and delicate brain
 The cranial meninges: the dura mater,
arachnoid, pia mater, are continuous
with those of the spinal cord.
 8-14
 Dura mater: covers the brain and spinal
cord
 Epidural space separates the spinal dura
mater from the walls of the vertebral
canal
 The subarachnoid space of the
arachnoid layer contains cerebrospinal
fluid (CSF)
 CSF acts as a shock absorber and a
diffusion medium for dissolved gases,
nutrients, chemical messages and waste
products
 Pia mater is bound to the underlying
neural tissue.
The Spinal Cord
 In addition to relaying information to
and from the brain, the spinal cord
integrates and processes information
own its own.
 The spinal cord as 31 segments, each
associated with a pair of dorsal root
ganglia and their dorsal roots and a pair
of ventral roots.
 8-15
 The white matter contains myelinated
and unmyelinated axons
 The gray matter contains the cell bodies of
neurons and glial cells
 The projections of gray matter toward the
outer surface of the spinal cord are called
horns.
The Brain
 There are 6 segments to the adult brain
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Cerebrum
Diencephalon
Midbrain
Cerebellum
Pons
Medulla oblongata
 The central passageway of the brain
expands to form four chambers called
ventricles.
 CSF continuously circulates from the
ventricles and central canal of the spinal
cord into the subarachnoid space of the
meninges that surround the CNS
Cerebrum
The cerebrum is responsible for:
conscious thought
intellectual functions,
memory
complex involuntary motor patterns
 The surface of the cerebrum contains gyri
(elevated ridges) separated by sulci (shallow
depressions) or deeper groves (fissures)
 The longitudinal fissure separates the two
cerebral hemispheres.
 The central sulcus marks the boundary
between and frontal lobe and the parietal
lobe.
 Other sulci form the boundaries of the
temporal lobe and the occipital lobe.
 Each cerebral hemisphere receives
sensory information and generates
motor commands that concern the
opposite side of the body.
 The primary motor cortex of the
precentral gyrus directs voluntary
movements.
 The primary sensory cortex receives
somatic sensory information from
touch, pressure, pain and temperature
receptors.
 Association areas, control our ability to
understand sensory information and
coordinate a motor response
 The left hemisphere is usually the
categorical hemisphere which contains
the general interpretive and speech
centers and is responsible for language
based skills.
 The right hemisphere, or
representational hemisphere is
concerned with spatial relationships and
analyses
s
 The basal nuclei lie within the central
white matter and aid in the coordination
of learned movement patterns and
other somatic motor activities.
 The limbic system includes the
hippocampus, which is involved in
memory and learning and the mamillary
bodies which control reflex
 The limbic system includes the
hippocampus, which is involved in
memory and learning and the mamillary
bodies which control reflex movements
such as eating.
 The functions of the limbic system
involve emotional states and related
behavioral drives.
The Diencephalon
 Provides the switching and relay centers
necessary to integrate the conscious and
unconscious sensory and motor pathways.
Contains
pineal gland
choroid plexus
thalamus
hypothalamus
Thalamus
 Final relay point for ascending sensory
information
 Only a small portion of the arriving
sensory information is passed to the
cerebral cortex
 Rest is passed to the basal nuclei and
centers in the brain stem
Hypothalamus
 Important control and integrative centers
 Produces emotions and behavior drives
 Coordinates activities of the nervous and
endocrine system
 Secretes hormones,
 Coordinate voluntary and autonomic functions
 Regulates body temperature
The Brain Stem
 Three regions
 The midbrain processes visual and auditory
information and generates involuntary somatic
motor responses.
 Pons connects the cerebellum to the brain stem
and is involved with somatic and visceral motor
control
 Medulla oblongata: connects to spinal cord relays
sensory information and regulates autonomic
functions.
Cerebellum
 Oversees the body’s postural muscles
and programs and tunes voluntary and
involuntary movements
 Cerebellar peduncles are tracts that link
the cerebellum with the brain stem,
cerebrum and spinal cord.
More medulla…
 Medulla oblongata connects the brain to the
spinal cord.
 Its nuclei relay information from the spinal
cord and brain stem to the cerebral cortex.
 Its reflex centers including the cardiovascular
centers and the respiratory rhythmicity
centers, control or adjust the activities of one
or more peripheral systems.