Download The Nervous System - El Camino College

Psych 7 Mascolo Course Notes – Neuroanatomy – Richard Mascolo, Ph.D.
Chapter 3 -- The Nervous System
Basic distinction of the nervous system: CNS vs. PNS:
Central Nervous System
Brain & Spinal cord
vs.
Peripheral Nervous System
Everything else
Some PNS neurons bring information to the CNS, others take information away from the CNS:
 Afferent = Sensory = “To be affected by something” these neurons gather info from the
body/outside world & bring it to the CNS
 Efferent = Motor = “To effect a change” -- these neurons gather commands from the CNS
& deliver them to the body
The CNS & PNS can be distinguished in terms of both Structure & Function
 Structures of the CNS not shared by PNS are protective

Encased in bone (skull & vertebrae)
Wrapped in Meninges (Dura Mater, Arachnoid, Pia Mater)
Bathed in Cerebral Spinal Fluid (CSF) – buoyed, cushioned, nourished (Fig. 3.3)
Isolated by Blood/Brain Barrier (Endothelial Cells that line inside of arteries are tightly
compacted in the cerebral arteries as well as coronary arteries) – cannot cross unless:
Very small
Fat soluble (Dissolve across Endothelial Cells)
Actively transported (e.g., Glucose)
Functions of the CNS not shared by the PNS are based in the evaluation & analysis of information
Simple Transmission (PNS) vs. Transmission + Analysis (CNS)
Cells of Nervous System


Neurons
Organelles in the soma control cellular functions
Covered by cell membrane -- phospholipid bilayer – evolutionarily successful – built passively
(self-organizing hydrophilic “heads” & hydrophobic “tails”)
Psych 7 Mascolo Course Notes – Neuroanatomy – Richard Mascolo, Ph.D.
Glial Cells
 “ Glue” (maintain structure) but not just this function defined early on; also
 clear debris, store & release NTs, even transmission
And now – Lots of terminology
CNS/PNS
CNS
PNS
Cell Bodies & Dendrites
Nuclei
Ganglia
Axons
Tracts
Nerves
Glials
Ogliodendrocytes
Schwann cells
Directional Terms - Relative to animal’s “Neuraxis” (not a term in your text) – bent at right angle in
humans.
Terms (Paired)
Directions
Examples
Anterior – Posterior
Rostral – Caudal
Front-Back
Beak-Tail
Central Sulcus divides Frontal Lobe (Anterior)
from Parietal Lobe (Posterior)
Ventral – Dorsal
Belly Side -- Back Side
Spinal Nerve Roots:
Sensory (Dorsal); Motor (Ventral)
Superior* – Inferior
Above -- Below
Lateral Fissure divides Frontal & Parietal Lobes
(Superior) from Temporal Lobe (Inferior)
Medial – Lateral
Toward Midline -Away from Midline
Nose (Medial) – Ears (Lateral)
Proximal—Distal
Close - Far
“approximate” “distant”
Psych 7 Mascolo Course Notes – Neuroanatomy – Richard Mascolo, Ph.D.
*Note: Because the human neuraxis is bent at a right angle, the Superior direction is also
considered Dorsal, and the Inferior direction is also considered Ventral
Perspectives: 1 for each of 3 Dimensions (and Other
Terms)
Term
Direction
Frontal (Coronal)
Front – Back
Sagittal
Side to Side
Horizontal
Top -- Bottom
Contralateral
Opposite Sides (Decussate)
Ipsilateral
Same Sides
Bilateral
Both Sides
Lamina
Parallel to cortical surface – e.g., Cerebral Cortex -- Layers I - VI,
see Brodmann’s “Cytoarchitecture” below
Column
Perpendicular to cortical surface
Example:
This is a Sagittal view of the Lateral surface of the Left cerebral
hemisphere
Now – Fill in the blanks:
Psych 7 Mascolo Course Notes – Neuroanatomy – Richard Mascolo, Ph.D.
This is a _______ view of the ______ surface of the
________ cerebral hemisphere (that is, the left
cerebral hemisphere has been removed)
This is a __________ view of the cerebral
hemispheres, which are separated by the _________
Fissure
Psych 7 Mascolo Course Notes – Neuroanatomy – Richard Mascolo, Ph.D.
Brodmann (1909) divided the cytoarchitecture of the 6 cortical laminae into 52 different areas
– much more detailed than 4 lobes
Psych 7 Mascolo Course Notes – Neuroanatomy – Richard Mascolo, Ph.D.
CNS connections to PNS & Body:

Brain: 12 cranial nerves:


“On Old Olympus Towering Tops A German And Fin VIewed Some Hops” – a
mnemonic for remembering the names of the 12 cranial nerves (Olfactory,
Optic, Oculomotor, Trochlear, … (we’re not memorizing these, but I’ll mention a
few of them later on)
Spinal cord: 31 pairs of spinal nerves: Starting with the most superior, they are:

1-8 Cervical -- 8

9-20 Thoracic -- 12

21-25 Lumbar -- 5

26-30 Sacral -- 5

1 Coccygeal -- 1

Total = 31
Each pair exits via a Dorsal Nerve Root (sensory) and Ventral Nerve Root (motor) -- can
distinguish by presence of Dorsal Nerve Root ganglion
Autonomic Nervous System -- Structural Differences lead to Functional Differences:
Sympathetic Branch
Parasympathetic Branch
activation
“Sympathetically”
Discretely
location
Contiguous:
Thoracic & Lumbar
Separated: Cranial & Sacral
Length of Pre vs Post
Ganglionic fibers
Short Pre, Long Post
(connected)
Long Pre, Short Post (separated)
So the Sympathetic Nervous System is hardwired to alarm the entire body – increase heart
rate as well as respiration, activate sweat glands, etc. In the diagram below you can see how
the sympathetic spinal nerves are all close to each other as they exit the spinal cord – if part
becomes activated, the whole system responds as well – that’s the “in sympathy” part
The Parasympathetic Nervous System, on the other hand, is hardwired to effect a “relaxation
response” in specific parts of the body – much more subtle than the “3 alarm blaze” of the
Psych 7 Mascolo Course Notes – Neuroanatomy – Richard Mascolo, Ph.D.
Sympathetic Nervous System. So as a species we are hard wired to stress out – very
adaptive when life was filled with physical danger, but not so great now that we are “civilized”.
Here’s another diagram showing the structural & functional differences of the Sympathetic &
Parasympathetic Nervous Systems:
Psych 7 Mascolo Course Notes – Neuroanatomy – Richard Mascolo, Ph.D.
I’ve added some detail (and color-coding) to Figure 3.29 here:
Major Brain
Area
Telencephalon
Major Features
or Structures
Cerebral Lobes
Major Fissures
Substructures
Basic Functions
Frontal
Organization & Planning – greatest difference
between humans & other mammals
Audition, Visual Recognition
Body awareness
Vision
Separates Left & Right Cerebral Hemispheres
Temporal
Parietal
Occipital
Longitudinal
Fissure
Lateral Fissure
Central Sulcus
Major Gyri
Limbic System
Diencephalon
Mesencepahon
Basal Ganglia
Corpus
Callosum
Thalamus
Hpothalamus
Periaqueductal
gray
Metencephalon Pons
Cerebellum
Reticular
Formation
Myencephalon Medulla
Precentral
Gyrus
Postcentral
Gyrus
Superior
Temporal
Gyrus
Amygdala
Hippocampus
Separates Frontal & Parietal Lobes (Superior)
from Temporal Lobe (Inferior)
Separates Frontal Lobe (Anterior) from Parietal
Lobe (Posterior)
Primary Motor Cortex
Primary Somatosensory Cortex
Primary Auditory Cortex
Conditioned Fear/Anxiety
Formation of Long Term Memories
Movement, Cognitive Functions
Major Connection between Left & Right Cerebral
Hemispheres
Major Sensory Relay – Vision, Audition
Motivational Emotions, Behaviors – Hunger,
Thirst, Sex
Endorphin & Opiate Receptors
Neurons Decussate (Cross Over Left-Right)
Movement, Conditioned Memories, Verbal Skills
Consciousness & Awareness
Vital Reflexes – Sneezing coughing, vomiting;
circulation & respiration