Download Neuroanatomy The central nervous system (CNS)

Human brain
Neuroanatomy
The central nervous system (CNS)
Dr. Haythem Ali Alsayigh
MBCHB-FIMBS
Surgical Clinical Anatomy
University of Babylon-College of Medicine
Objective
 1-topography of the nervous system
 2-meninges of the brain and spinal cord
 3-blood supply and clinical probles pituitary gland
 4-basal ganglia
 5-limbic system
 6-CSF &ventricles
 7-Spinal cord
 8-Medulla oblengata
 8- pone
 9-btain stem
 10-cerebellum
 11-Anatomy of
12-
ORGANIZATION OF THE NERVOUS
SYSTEM
BRAIN
SPINAL CORD
CENTRAL
NERVOUS
SYSTEM (CNS)
AFFERENT
EFFERENT
NERVES
NERVES
EXTEROINTERORECEPTORS RECEPTORS
EFFECTOR
ORGANS
PERIPHERAL
NERVOUS
SYSTEM
SOMATIC
SKELETAL
MUSCLES1
AUTONOMIC
SMOOTH AND
CARDIAC MUSCLES
AND GLANDS
Functions of the Nervous System
 1-Sensory input: Monitor internal and external
stimuli (change)
Touch, odor, sound, vision, taste, bp, body temp.
 2-Integration. Brain and spinal cord process
sensory input and initiate responses
 3-Motor output: Controls of muscles and glands
 4-Homeostasis. Regulate and coordinate
physiology
 5-Mental activity. Consciousness, thinking,
memory, emotion
11-4
MAINTENANCE AND PROTECTION OF THE
CNS
 1-Glial Cells: physical and metabolic support
 2-Skull and Spinal Column
 3-Cerebrospinal fluid
 4-Blood-brain barrier
 5-Blood supply
The Nervous System
 Components
 Brain, spinal cord, nerves, and sensory
receptors
 Subdivisions
 Central nervous system (CNS): brain and
spinal cord
 Peripheral nervous system (PNS)
 Nerves: Sensory and Motor
11-6
Peripheral Nervous System
 Outside the CNS
 Divided into
 Sensory (Afferent) Division -incoming information
 Motor (Efferent Division - outgoing information
 Sensory Division
 Use sensory neurons to transmit nerve impulses toward the brain and
spinal cord
 Receptors in various body locations react to stimuli (touch, pressure,
heat, stretch, light, etc) and trigger a nerve impulse in the sensory
neuron
 Motor Division
 Use motor neurons to transmit nerve impulses away from the brain
11-7
and spinal cord
 Stimulate effectors (muscle and glands)
Divisions of PNS
 Sensory (afferent): transmits
nerve impulses from receptors to
CNS.
 Motor (efferent): transmits
nerve impulses from CNS to
effectors (muscles, glands)
11-8
Types of Sensory and Motor
Information
11-9
Sensory Division of the PNS
 Transmit nerve impulses over sensory neurons to the CNS from
receptors
 Receptors are classified as:
 Somatic receptors - those found in skin, joints, skeletal muscles, and
special sense organs
 Respond to touch, pressure, heat, stretch, pain, light
 Visceral receptors - located in walls of viscera
 Respond to stretch, pain, temperature, chemical stimuli (CO2)
11-10
Motor Division of PNS
 Transmits impulses away from the CNS to effectors
 Effector - any muscle or gland
 Somatic nervous system:
 Regulates contraction of skeletal muscles.
 Under our voluntary control - I.e., under conscious control
 Autonomic nervous system (ANS)
 Regulates contraction of smooth muscle, cardiac muscle and glands (visceral organs)
 Subconscious or involuntary control.
 Divisions of the ANS
 Sympathetic. Prepares body for physical activity.
 Parasympathetic. Regulates resting or vegetative functions such as digesting food
or emptying of the urinary bladder.
11-11
Cells of Nervous System
 Neurons
 The functional unit of the nervous system
 Transmit electrical signals (action potentials) to other neurons or
effectors
 Neuroglia (Glial cells)
 Nonexcitable
 Support and protect neurons
11-12
The Neuron
 Special characteristics of neurons
 Longevity – can live and function for a lifetime
 Do not divide (amitotic) – fetal neurons lose their ability to undergo
mitosis; neural stem cells are an exception
 High metabolic rate – require abundant oxygen and glucose
11-13
Parts of the Neuron
 Cell Body. Aka Soma or Perikaryon
 Contains usual organelles plus other
structures
 Nissl bodies = chromatophilic substance =
rough E.R: primary site of protein
synthesis
 Cytoskeleton of neurofilaments and
neurotubules
 No centrioles (hence its amitotic nature)
 Major biosynthetic center
 Most neuronal cell bodies
 Located within CNS
 Ganglia - clusters of cell bodies that lie
along nerves in PNS
 Tapers to form axon hillock
11-14
Neuron Processes
 Dendrites: short, often highly branched.
 Receptive regions of the neuron
 Axons. Long cytoplasmic process capable of
propagating a nerve impulse
 Neuron has only one
 Transmits impulse away from soma
 Axon hillock: Initial segment
 Few, if any, branches along length
 Multiple branches at end of axon
 Terminal branches (telodendria)

11-15
End in knobs called axon terminals (aka
synaptic terminals, end bulbs, boutons, synaptic
knobs)
o Contain vesicles filled with neurotransmitter (NT)
Axoplasmic Transport
 Anterograde:
 Axoplasm moved from cell body toward terminals.
 Supply materials for growth, repair, renewal.
 Can move cytoskeletal proteins, organelles away from cell body
toward axon terminals.
 Retrograde
 Away from axonal terminal toward the cell body
 Damaged organelles, recycled plasma membrane, and substances
taken in by endocytosis can be transported up axon to cell body.
 Rabies and herpes virus can enter axons in damaged skin and be
transported to CNS. Would include toxins such as heavy metals (the
chemical, not the noise)
11-16
Classification of Neurons
 Structural classification
 Multipolar – possess more than two processes
 Numerous dendrites and one axon
 Bipolar – possess two processes
 Rare neurons – found in some special sensory organs
 Unipolar (pseudounipolar) – possess one short, single process
 Start as bipolar neurons during development
11-17
Neurons Classified by Structure
11-18
Figure 12.10a–c
Structural Classes of Neurons
11-19
Table 11.1.2
Functional Classification of
Neurons
 According to the direction the nerve impulse travels
 Sensory (afferent) neurons –
transmit impulses toward the CNS
 Virtually all are unipolar neurons
 Cell bodies in ganglia outside the CNS
 Short, single process divides into


11-20
The central process – runs centrally into the CNS
The peripheral process – extends peripherally to the
receptors
Functional Classification of
Neurons
 Motor (efferent) neurons




Carry impulses away from the CNS to effector organs
Most motor neurons are multipolar
Cell bodies are within the CNS
Form junctions with effector cells
 Interneurons (association neurons) – most are multipolar
 Lie between 2 neurons
 Confined to the CNS
11-21
Neurons Classified by Function
11-22
Figure 12.11
Supporting Cells (Neuroglial Cells)
in the CNS
 Neuroglia – usually only refers to supporting cells in the
CNS




Glial cells have branching processes and a central cell body
Outnumber neurons 10 to 1
Make up half the mass of the brain
Can divide throughout life
 May divide abnormally - glioma - brain cancer
 Do not transmit nerve impulses
11-23
Neuroglia of CNS: Astrocytes


Largest and most numerous
Functions include:
1. Form the blood-brain barrier

Take up and release ions (Na, K) to
control the environment around neurons

Regulate what substances reach the CNS
from the blood
2. Reapture and recycle neurotrans-mitters
3. Involved with synapse formation in
developing neural tissue
4. Aid in repair of damaged neural tissue
5. Produce molecules necessary for neural
growth (BDTF)
11-24
Neuroglia of CNS: Ependymal Cells
 Line brain ventricles and
spinal cord central canal.
 Specialized versions of
ependymal form choroid plexuses.
 Choroid plexus
 Secrete cerebrospinal fluid. Cilia
help move fluid thru the cavities
of the brain.
11-25
Neuroglia of CNS: Microglia and
Oligodendrocytes
 Microglia: specialized macrophages. Respond to inflammation,
phagocytize necrotic tissue, microorganisms, and foreign substances
that invade the CNS.
 Oligodendrocytes: form myelin sheaths if surrounding axon. Single
oligodendrocytes can form myelin sheaths around portions of several
axons.
11-26
Neuroglia of PNS
 Schwann cells or neurolemmocytes:
 Wrap around portion of only one axon to form myelin sheath.
 Wrap around many times.
 As cells grow around axon, cytoplasm is squeezed out and multiple layers of
cell membrane wrap the axon. Cell membrane primarily phospholipid.
 Outer surface of Schwann cell called the neurilemma
 Satellite cells: surround neuron cell bodies in ganglia, provide
support and nutrients
11-27
Myelin Sheaths
 Segmented structures composed of the lipoprotein myelin
 Surround thicker axons
 Form an insulating layer
 Prevent leakage of electrical current
 Increase the speed of impulse conduction
11-28
Myelin Sheaths in the PNS
 Formed by Schwann cells
 Develop during fetal period and in the first
year of postnatal life
 Schwann cells wrap in concentric layers
around the axon
 Cover the axon in a tightly packed coil of
membranes
 Neurilemma – material external to
myelin layers
 Nodes of Ranvier – gaps along axon
 Degeneration of myelin sheaths
occurs in multiple sclerosis and
some cases of diabetes mellitus.
11-29
Structure of a Nerve
A. Note the similarity of a nerve to a muscle
1. Just as a muscle is a collection of muscle
fibers, a nerve is a collection of nerve fibers
(axons).
2. Each is broken up in smaller units known as
fascicles
3. Each is covered by connective tissue:
•
Epimysium vs. Epineurium
•
Perimysium vs. Perineurium
•
Endomysium vs. Endoneurium
11-30
Figure 12.16a
Nerve Fiber Types
 Type A fibers
 large-diameter nerve
 Heavily myelinated; conduct impulses at 15-120 m/sec
 Motor neurons supplying skeletal muscles
 Type B
 medium-diameter nerves
 lightly myelinated; conduct at 3-15 m/sec
 Sensory nerves from sensory receptors
 Type C:
 Very small diameter
 Unmyelinated; conduct at 2 m/sec or less
 Part of ANS
 Innervate visceral smooth muscle and glands
11-31
The Synapse
 Site at which neurons communicate
 Signals pass across synapse in one direction
 Types of cells in synapse
 Presynaptic neuron - conducts impulse toward the synapse
 Postsynaptic neuron - conducts impulse away from the synapse
 Average postsynaptic neuron has up to 10,000 synapses
 Some in cerebellum have up to 100,000 synapses
 Two major types of synapses
 Electrical - not common in nervous system
 Chemical - most common type
11-32
Types of Chemical Synapses
 Axodendritic
 Between axon terminals of presynaptic neuron and dendrite of
postsynaptic neuron
 Most common type of synapse
 Axosomatic
 Between axon of pre- and soma (cell body) of post-synaptic
neuron
 Axoaxonic
 Between two axons
 Not common
11-33
Types of Neural Synapses
11-34
Chemical
Synapse
• Presynaptic bulb has secretory
vesicles that contain neurotransmitter chemical (NT)
• NT must pass across the
synaptic cleft, space that
separates pre- and
postsynaptic membranes
• Postsynaptic membrane
contains receptors specific
for each type of NT
• Binding of NT to its receptor
causes ion channels to open
or close
• Postsynaptic membrane is thus
either stimulated or inhibited
11-35
Basic Neuronal Organization of the
Nervous System
 Reflex arcs – simple chains of neurons
 Explain reflex behaviors
 Determine structural plan of the nervous system
 Responsible for reflexes
 Rapid, autonomic motor responses

11-36
Can be visceral or somatic
Five Essential Components to the
Reflex Arc
 Receptor – site where stimulus acts
 Sensory neuron – transmits afferent
impulses to the CNS
 Integration center – consists of one
or more synapses in the CNS
 Motor neuron – conducts efferent
impulses from integration center to
an effector
 Effector – muscle or gland
 Responds to efferent impulses
 Contracting or secreting
11-37
Types of Reflexes
 Monosynaptic reflex – simplest of all reflexes
 Just one synapse
 The fastest of all reflexes
 Example – knee-jerk reflex
 Polysynaptic reflex – more common type of reflex
 Most have a single interneuron between the sensory and motor
neuron
 Example – withdrawal reflexes
11-38
Types of Reflexes
11-39
Simplified Design of the Nervous
System
 Three-neuron reflex arcs
 Basis of the structural plan of the nervous system
 Similar reflexes are associated with the brain
11-40
Simplified Design of the Nervous
System
 Sensory neurons – located dorsally
 Cell bodies outside the CNS in sensory ganglia
 Central processes enter dorsal aspect of the spinal cord
 Motor neurons – located ventrally
 Axons exit the ventral aspect of the spinal cord
 Interneurons – located centrally
 Synapse with sensory neurons
11-41
Simplified Design of the Nervous
System
 Human nervous system is complex
 Interneurons also include neurons confined to CNS
 Long chains of interneurons between sensory and motor
neurons
11-42
Simplified Design of the Nervous System
11-43
Neuronal Pathways and Circuits
 Organization of neurons in CNS varies in complexity
 Convergent pathways: many neurons converge and synapse with smaller number
of neurons. E.g., synthesis of data in brain.
 Divergent pathways: small number of presynaptic neurons synapse with large
number of postsynaptic neurons. E.g., important information can be transmitted to
many parts of the brain.
11-44
Disorders of the Nervous System
 Multiple sclerosis – common cause of neural disability
 Varies widely in intensity among those affected
 Cause is incompletely understood
 An autoimmune disease
 Immune system attacks the myelin around axons in the CNS
11-45
Neuronal Regeneration
 Neural injuries may cause permanent dysfunction
 If axons alone are destroyed, cells bodies often survive
and the axons may regenerate
 PNS – macrophages invade and destroy axon distal to the injury
 Axon filaments grow peripherally from injured site
 Partial recovery is sometimes possible
 CNS – neuroglia never form bands to guide regrowing axons
and may hinder axon growth with growth-inhibiting chemicals
 No effective regeneration after injury to the spinal chord and
brain
11-46
Regeneration
of the
Peripheral
Nerve Fiber
11-47
 The central nervous system (CNS) is the
part of the nervous system that integrates the
information that it receives from, and
coordinates the activity of, all parts of the
bodies of bilaterian animals—that is, all
multicellular animals contains the majority of
the nervous system and consists of the brain
and the spinal cord.
Neuroanatomy
 The central nervous system (CNS) is the part of the nervous
system that
 integrates the information that it receives from, and coordinates
the activity of, all parts of the bodies of bilaterian animals—that
is, all multicellular animals contains the majority of the nervous
system and consists of the brain and the spinal cord.
 Some classifications also include the retina and the cranial
nerves in the CNS. Together with the peripheral nervous
system, it has a fundamental role in the control of behavior.
 The CNS is contained within the dorsal cavity, with the brain
in the cranial cavity and the spinal cord in the spinal cavity.
In vertebrates, the brain is protected by the skull, while the
spinal cord is protected by the vertebrae, and both are
enclosed in the meninges
Developments
 During early development of the vertebrate embryo, a
longitudinal groove on the neural plate gradually
deepens as ridges on either side of the groove (the neural
folds) become elevated, and ultimately meet,
transforming the groove into a closed tube, the
ectodermal wall of which forms the rudiment of the
nervous system.
 This tube initially differentiates into three
vesicles (pockets): the
prosencephalon at the front, the mesencephalon, and, between
the mesencephalon and the spinal cord, the rhombencephalon.
 (By six weeks in the human embryo) the prosencephalon
then divides further into the telencephalon and
diencephalon;
 and the rhombencephalon divides into the metencephalon and
myelencephalon.
 This tube initially differentiates into three vesicles (pockets):
 the prosencephalon at the front,
 the mesencephalon, and,
 between the mesencephalon and the spinal cord,
 the rhombencephalon.
 (By six weeks in the human embryo) the
divides further into the
 telencephalon and
 diencephalon;
prosencephalon then
 and the rhombencephalon divides into the
 metencephalon and
 myelencephalon.
 As the vertebrate grows, these vesicles differentiate
further still.
 The telencephalon differentiates
into, among other things, the
striatum, the hippocampus and the
neocortex, and its cavity becomes
the first and second ventricles.
 Diencephalon elaborations include the
subthalamus, hypothalamus, thalamus and
epithalamus, and its cavity forms the third
ventricle.
 The tectum, pretectum, cerebral peduncle
and other structures develop out of the
mesencephalon, and its cavity grows into the
mesencephalic duct (cerebral aqueduct).
 The metencephalon becomes, among other
things, the pons and the cerebellum, the
myelencephalon forms the medulla
oblongata, and their cavities develop into the
fourth ventricle.

The human brain
 The human brain has the same general structure as the
brains of other mammals, but is larger than expected on
the basis of body size among other primates
 Estimates for the number of neurons (nerve cells) in the human
brain range from 80 to 120 billion.Most of the expansion comes
from the cerebral cortex, especially the frontal lobes, which are
associated with executive functions such as self-control, planning,
reasoning, and abstract thought.
 The portion of the cerebral cortex devoted to vision is also greatly
enlarged in human beings, and several cortical areas play specific
roles in language, a skill that is unique to humans.
The human brain
 Despite being protected by the thick bones of the skull,
suspended in cerebrospinal fluid, and isolated from the
bloodstream by the blood-brain barrier, the human brain is
susceptible to many types of damage and disease.
 The most common forms of physical damage are closed head
injuries such as a blow to the head, a stroke, or poisoning by a
variety of chemicals that can act as neurotoxins.
 Infection of the brain, though serious, is rare due to the
biological barriers which protect it.
 The human brain is also susceptible to degenerative disorders, such as
Parkinson's disease, multiple sclerosis, and Alzheimer's disease. A number
of psychiatric conditions, such as schizophrenia and depression, are
thought to be associated with brain dysfunctions, although the nature of
such brain anomalies is not well understood
Contents
1 Structure
1.1 General features
1.2 Cortical divisions
 1.2.1 Four lobes
 1.2.2 Major folds
1.3 Functional divisions
 1.3.1 Cytoarchitecture
 1.3.2 Topography

 2 Cognition
 3 Lateralization
 4 Development
 5 Evolution
 6 Sources of information







6.1 EEG
6.2 MEG
6.3 Structural and functional imaging
6.4 Effects of brain damage
7 Language
8 Pathology
9 Metabolism
Brain size
The adult human brain weighs on
average about 3 lb (1.5 kg)] with
a size (volume) of around 1130
cubic centimetres (cm3) in
women and 1260 cm3 in men,
although there is substantial
individual variation.
Neanderthals, an extinct
subspecies of modern humans,
had larger brains at adulthood
than present-day humans.
Men with the same body height
and body surface area as
women have on average 100g
heavier brains, although these
differences do not correlate in
any simple way with gray
matter neuron counts or with
overall measures of cognitive
performance
 The brain is very soft, having a consistency
similar to soft gelatin or soft tofu.
 Despite being referred to as "grey matter", the
live cortex is pinkish-beige in color and slightly
off-white in the interior.
 At the age of 20, a man has around 176,000 km
and a woman about 149,000 km of myelinated
axons in their brains
General features
 The cerebral hemispheres form the largest part of the human brain




and are situated above most other brain structures. They are
covered with a cortical layer with a convoluted topography.
Underneath the cerebrum lies the brainstem, resembling a stalk on
which the cerebrum is attached.
At the rear of the brain, beneath the cerebrum and behind the
brainstem, is the cerebellum, a structure with a horizontally
furrowed surface that makes it look different from any other brain
area.
The same structures are present in other mammals, although the
cerebellum is not so large relative to the rest of the brain. As a rule,
the smaller the cerebrum, the less convoluted the cortex.
The cortex of a rat or mouse is almost completely smooth. The
cortex of a dolphin or whale, on the other hand, is more
convoluted than the cortex of a human.
General features
 The dominant feature of the human brain is corticalization. The cerebral
cortex in humans is so large that it overshadows every other part of the
brain.
 A few subcortical structures show alterations reflecting this trend. The
cerebellum, for example, has a medial zone connected mainly to
subcortical motor areas, and a lateral zone connected primarily to the
cortex. In humans the lateral zone takes up a much larger fraction of the
cerebellum than in most other mammalian species. Corticalization is
reflected in function as well as structure. The cerebral cortex is
essentially a sheet of neural tissue, folded in a way that
allows a large surface area to fit within the confines of the
skull. Each cerebral hemisphere, in fact, has a total surface
area of about 1.3 square feet.[16] Anatomists call each
cortical fold a sulcus, and the smooth area between folds a
gyrus
Four lobes
Cortical divisions

Four lobes
 The four lobes of the cerebral cortex
 The cerebral cortex is nearly symmetrical, with left and right hemispheres that
are approximate mirror images of each other. Anatomists conventionally divide
each hemisphere into four "lobes", the frontal lobe, parietal lobe, occipital
lobe, and temporal lobe. This division into lobes does not actually arise from
the structure of the cortex itself, though: the lobes are named after the bones of
the skull that overlie them, the frontal bone, parietal bone, temporal bone, and
occipital bone.
 The borders between lobes are placed beneath the sutures that link the skull
bones together. There is one exception: the border between the frontal and
parietal lobes is shifted backward from the corresponding suture, to the central
sulcus, a deep fold that marks the line where the primary somatosensory cortex
and primary motor cortex come together.
 Because of the arbitrary way most of the borders between
lobes are demarcated, they have little functional significance.
With the exception of the occipital lobe, a small area that is
entirely dedicated to vision, each of the lobes contains a
variety of brain areas that have minimal functional
relationship.
 The parietal lobe, for example, contains areas involved in
somatosensation, hearing, language, attention, and spatial
cognition. In spite of this heterogeneity, the division into
lobes is convenient for reference, and is universally used.
The frontal lobe
 The frontal lobe is located at the front of the brain and is
associated with reasoning, motor skills, higher level
cognition, and expressive language.
 At the back of the frontal lobe, near the central sulcus, lies
the motor cortex.
 This area of the brain receives information from various lobes
of the brain and utilizes this information to carry out body
movements.
 Damage to the frontal lobe can lead to changes in sexual
habits, socialization, attention as well as increased risk-taking
Frontal Lobe
 Behavior ,Abstract thought processes ,Problem solving
,Attention , Creative thought ,Some emotion ,Intellect
,Reflection ,Judgment ,Initiative , Inhibition ,Coordination of
movements ,Generalized and mass movements , Some eye
movements ,Sense of smell ,Muscle movements ,Skilled
movements ,Some motor skills ,Physical reaction, Libido
(sexual urges)
The parietal lobe
 The parietal lobe is located in the middle section of the
brain and is associated with processing tactile sensory
information such as pressure,
 touch, and pain.
 A portion of the brain known as the somatosensory cortex is
located in this lobe and is essential to the processing of the
body's senses.
 Damage to the parietal lobe can result in problems with
verbal memory, an impaired ability to control eye gaze and
problems with language among other ailments.
Parietal Lobe
 Sense of touch (tactile senstation)
 Appreciation of form through touch (stereognosis)
 Response to internal stimuli (proprioception)
 Sensory combination and comprehension
 Some language and reading functions
 Some visual functions
The temporal lobe
 The temporal lobe is located on the bottom section of the
brain.
 This lobe is also the location of the primary auditory cortex,
which is important for interpreting sounds and the language
we hear.
 The hippocampus is also located in the temporal lobe, which
is why this portion of the brain is also heavily associated with
the formation of memories.
 Damage to the temporal lobe can lead to problems with
memory, speech perception and language skills.
Temporal Lobe
 Auditory memories
 Some hearing
 Visual memories
 Some vision pathways
 Other memory
 Music
 Fear
 Some language
 Some speech
 Some behavior amd emotions
 Sense of identity
The occipital lobe
 The occipital lobe is located at the back portion of the
brain and is associated with interpreting visual stimuli and
information.
 The primary visual cortex, which receives and interprets
information from the retinas of the eyes, is located in the
occipital lobe.
 Damage to this lobe can cause visual problems such as
difficulty recognizing objects, an inability to
identify colors and trouble recognizing words.
Occipital Lobe
Vision
Reading
 Right Hemisphere (the representational







hemisphere)
The right hemisphere controls the left side of the body
Temporal and spatial relationships
Analyzing nonverbal information
Communicating emotion
Left Hemisphere (the categorical hemisphere)
The left hemisphere controls the right side of the body
Produce and understand language
 Corpus Callosum
 Communication between the left and right side of the brain
 THE CEREBELLUM
 Balance
 Posture
 Cardiac, respiratory, and vasomotor centers
 THE BRAIN STEM
 Motor and sensory pathway to body and face
 Vital centers: cardiac, respiratory, vasomotor
 Hypothalamus
 Moods and motivation
 Sexual maturation
 Temperature regulation
 Hormonal body processes
 Optic Chiasm
 Vision and the optic nerve
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 Pituitary Gland
 Hormonal body processes
 Physical maturation
 Growth (height and form)
 Sexual maturation
 Sexual functioning
 Spinal Cord
 Conduit and source of sensation and movement
 Pineal Body
 Unknown
 Ventricles and Cerebral Aqueduct
 Contains the cerebrospinal fluid that bathes the brain and spinal
cord
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 The Hindbrain
 The hindbrain is the structure
The Brain Stem
The brain stem is comprised of the
hindbrain and midbrain. The hindbrain
contains structures including medulla,
the pons and the reticular formation
that connects the spinal cord to
the brain.
The medulla is located directly
above the spinal cord and
controls many vital autonomic
functions such as heart rate,
breathing and blood pressure.
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 The pons connects the medulla
to the cerebellum and helps
coordinate movement on each
side of the body.
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 The reticular formation is a
neural network located in the
medulla that helps control
functions such as sleep and
attention.
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The Midbrain
 The midbrain is the smallest region of the
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brain that acts as a sort of relay station for
auditory and visual information.
The midbrain controls many important
functions such as the
visual and
auditory systems
as well as eye movement. Portions of the
midbrain called the red nucleus and the
substantia nigra are involved in the control
of body movement. The darkly pigmented
substantia nigra contains a large number of
dopamine-producing neurons are located. The
degeneration of neurons in the substantia
nigra is associated with Parkinson’s disease.
The Cerebellum
 Sometimes referred to as the "little brain," the cerebellum lies on
top of the pons, behind the brain stem. The cerebellum is comprised
of small lobes and receives information from the balance system of
the inner ear, sensory nerves, and the auditory and visual systems. It
is involved in the coordination of motor movements as well as basic
facets of memory and learning.
The Thalamus
 Located above the brainstem, the thalamus processes and relays
movement and sensory information. It is essentially a relay
station, taking in sensory information and then passing it on to the
cerebral cortex. The cerebral cortex also sends information to the
thalamus, which then sends this information to other systems.
The Hypothalamus
 The hypothalamus is a grouping of nuclei that lie along the base of
the brain near the pituitary gland. The hypothalamus connects with
many other regions of the brain and is responsible for controlling
hunger, thirst, emotions, body temperature regulation,
and circadian rhythms.The hypothalamus also controls the
pituitary gland by secreting hormones, which gives the
hypothalamus a great deal of control over many body functions
The Limbic System
 The amygdala is one of the major structures found in the limbic
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system.
The limbic system is comprised of four main structures:
the amygdala,
the hippocampus,
regions of the limbic cortex and
the septal area.
These structures form connections between the limbic system and
the hypothalamus, thalamus and cerebral cortex. The hippocampus is
important in memory and learning, while the limbic system itself is
central in the control of emotional responses.
The Basal Ganglia
 The basal ganglia are
a group of large
nuclei that partially
surround the
thalamus. These
nuclei are important
in the control of
movement.
 The red nucleus and
substantia nigra of
the midbrain have
connections with
the basal ganglia.
Major folds:
 Major gyri and sulci on the lateral surface of the cortex
 Although there are enough variations in the shape and placement of gyri and
sulci (cortical folds) to make every brain unique, most human brains show
sufficiently consistent patterns of folding that allow them to be named. Many of
the gyri and sulci are named according to the location on the lobes or other
major folds on the cortex.
These include:
 Superior, Middle, Inferior frontal gyrus: in reference to the frontal
lobe
 Precentral and Postcentral sulcus: in reference to the central sulcus
 Trans-occipital sulcus: in reference to the occipital lobe
 Deep folding features in the brain, such as the inter-hemispheric
and lateral fissure, which divides the left and right brain, and the
lateral sulcus, which "splits-off" the temporal lobe, are present in
almost all normal subjects
Functional divisions
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 Researchers who study the functions of the cortex divide it into three functional
categories of regions, or areas.
 One consists of the primary sensory areas, which receive signals from
the sensory nerves and tracts by way of relay nuclei in the thalamus. Primary sensory
areas include the visual area of the occipital lobe, the auditory area in parts of the
temporal lobe and insular cortex, and the somatosensory area in the parietal lobe.
 A second category is the primary motor area, which sends axons
down to motor neurons in the brainstem and spinal cord. This area occupies the rear
portion of the frontal lobe, directly in front of the somatosensory area.
 The third category consists of the remaining parts of the
cortex, which are called the association areas. These areas receive input from the
sensory areas and lower parts of the brain and are involved in the complex process that
we call perception, thought, and decision making.
Cytoarchitecture
Cytoarchitecture
 Different parts of the cerebral cortex are involved in different cognitive
and behavioral functions. The differences show up in a number of ways:
the effects of localized brain damage, regional activity patterns exposed
when the brain is examined using functional imaging techniques,
connectivity with subcortical areas, and regional differences in the
cellular architecture of the cortex. Anatomists describe most of the
cortex—the part they call isocortex—as having six layers, but not all
layers are apparent in all areas, and even when a layer is present, its
thickness and cellular organization may vary. Several anatomists have
constructed maps of cortical areas on the basis of variations in the
appearance of the layers as seen with a microscope. One of the most
widely used schemes came from Brodmann, who split the cortex into
51 different areas and assigned each a number (anatomists have since
subdivided many of the Brodmann areas). For example, Brodmann area
1 is the primary somatosensory cortex, Brodmann area 17 is the
primary visual cortex, and Brodmann area 25 is the anterior cingulate
cortex
Topography
 Topography of the primary motor cortex, showing which
body part is controlled by each zone