Central Nervous System (CNS): Brain and Spinal Cord

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Central Nervous System (CNS)Brain and Spinal
Cord

• Biology 211 AP 1
• Tony Serino, Ph.D.
• Biology Dept.
• Misericordia University

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Central Nervous System (CNS)

• Gray vs. White matter
• Protection of CNS
• Meninges
• CSF flow
• Brain
• Development
• Selected structures
• Spinal cord
• Selected structures

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CNS (Central Nervous System)

• Brian and spinal cord
• Displays gray and white matter
• Gray matter are areas of CNS with many cell
  bodies of neurons present (little myelinated
  nerve fibers)
• White matter are area of CNS with few cell bodies
  but many myelinated nerve fibers
• Protected by bone and membranes

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Gray and White Matter

• Since the cerebrum and cerebellum outgrow their
  cores, gray matter ends up on outside of both
  structures.

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Meninges

• Dura Mater outermost tough, fibrous CT
• In brain, divided into two layers (periosteal and
  meningeal)
• In spine, only one layer with fat filled space
  above the layer called the epidural space
• Arachnoid middle web-like appearance
• Potential space between Dura and arachnoid is the
  subdural space
• Pia Mater innermost, delicate membrane fused
  with CNS surface
• Space between Pia and Arachnoid is the
  subarachnoid space

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Meninges of the Spinal Cord
Pia mater
Epidural space
Arachnoid
Meninges
Dura mater
Subdural space
Subarachnoid space
Dorsal Root Ganglion
Centrum
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Brain Meninges
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Extensions of Dura Materhold brain in cavity
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Brain Ventricles
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Choroid Plexus
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CSF (cerebral-spinal fluid) Flow
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Hydrocephalus

• Blockage of CSF flow can lead to severe brain
  and/or head enlargement.
• In an adult, such swelling would be fatal.

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Brain Damage due to Pressure
Hematoma
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Brain

• Development
• Structures
• Functional Areas

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Neural Tube Formation
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Brain Vesicles
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Flexures and Cerebral Cortex Growth
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Major Divisions of Brain
Brain Stem midbrain pons medulla
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Brain Anatomy (reqd)
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Projections vs. Commissures
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Functional Anatomy of Brain
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Functional Areas of Cerebrum
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Communication

• Note difference in hearing vs. speaking words

Male vs. Female processing during a language task
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Electroencephalography (EEG)
The electroencephalograph (EEG) is the printout
of an electronic device that uses scalp
electrodes to monitor the internal neural
activity in the brain cortex.
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EEG as Clinical Tool
EEGs provide diagnostic information about the
location of abnormal activity in the brain,
such as shown in this record typical of a
patient undergoing an epileptic seizure.

• EEGs record largely the surface electrical
  activity of underlying brain areas
• Activity largely due to summated graded
  potentials of many neurons
• Amplitude shows how much activity (degree of
  summation and/or number of neurons)

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Primary Motor and Somatosensory Gyri
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Basal Nuclei cerebral nuclei
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RAS (Reticular Activating System)

• Brainstem nuclei intermingled with bundles of
  axons
• Receives and integrates input from all regions of
  CNS
• Involved in motor function, cardiac and
  respiratory control, attention, vasomotor
  control, sleep/wakefulness
• Extends along length of brain stem used in
  maintaining alertness while awake

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RAS receives inputs from eye, ear and general
sensation to maintain alertness
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Sleep Patterns

• NREM Stage 1? 4 decreasing eye and skeletal
  muscle movement, increased threshold for arousal,
  increase size but decrease freq. of EEG
• REM EEG freq. increases with less amplitude
  (alpha like), increase HR, Resp. Rate, and eye
  movement, but still in deep sleep, high oxygen
  consumption in brain dream sleep
• 4-5 cycles of NREM/REM sleep each night (every
  90 min)

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Importance of Sleep

• Slow wave sleep is thought to be restorative to
  brain function (Children have more total sleep
  time and are in stage 4 more than adults)
  Elderly have about the same total sleep time as
  adults but broken into smaller episodes, also
  spend less time in REM. Time spent in Stage 4
  declines with age.
• Person consistently deprived of REM may become
  moody or depressed may exhibit other personality
  disorders

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Coma Brain Death

• Coma is a severe loss in mental function due to
  brain damage sustained loss of arousal (even
  with heavy stimuli), behavior response is lost,
  no sleep/wake cycles
• Persistent Vegetative State sleep/wake cycles
  are present no sign of external awareness

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Limbic System functional system responsible for
emotion and memory
Cingulate Gyrus
Fornix
Mammillary body
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Learning Memory

• Learning acquisition and utilization of
  information from past experience
• Memory relatively permanent storage of
  information

• Declarative memory retention of conscious
  experience, facts, etc. uses Limbic system
  cortex (amygdala, hippocampus thalamus)
• Procedural memory knowledge of how to do
  something (skilled behaviors) uses sensory
  cortex, basal nuclei, cerebellum

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Memory Processing

• Automatic long term memory linked to noxious
  stimuli.
• Many long term memories may be unretrievable
  consciously, but may still exist within the brain
  

??
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Spinal Cord

• Receives and generates signals to body through
  the spinal nerves

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Spinal Cord (X.S.)
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Cord in Spinal Canal
Posterior Median Sulcus
Posterior Root
Denticulate Ligament
Dorsal Root Ganglion
Anterior Root
Spinal Nerve
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Spinal Cord Segments

• 4 segments Cervical, Thoracic, Lumbar, and
  Sacral (only 1 coccygeal nerve)
• 31 pairs of spinal nerves

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Cervical Segment
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Thoracic Segment
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Lumbar Segment
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Sacral Segment
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Cauda Equina
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Lumbar Puncture
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Functional Arrangement of SC