Chapter 1 Basic Anatomy

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Chapter 1 Basic Anatomy

• Chris Rorden
• Coordinates
• Introduction to the nervous system

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Multiple choice

• What is an example of a common mnemonic?
• Someone with blue eyes.
• Someone with odd eyes (one blue, one green).
• The left hand is controlled by the right side of
  the brain.
• Kings prefer chess over football, generally
  speaking.

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Mnemonics

• Mnemonics tools to aid memory
• Kings prefer chess over football generally
  speaking Kingdom, phylum, class, order, family,
  genus, species.
• My very easy method, just set up nine planets
  Mercury Venus Earth Mars Jupiter Saturn Neptune
  Pluto
• Other methods include loci (imagine a walk with
  different objects in different locations) or
  rhymes (one is a bun, two is a shoe)

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Multiple choice

• What is the symbol for Sagittarius?
• The Water Carrier.
• The Archer.
• The Sea-goat.
• The Lion.

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Sagittarius
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SLP and Neuroscience

• Speech-Language Pathology
• Study of developmental and acquired disorders of
  human cognition, language and speech
• Complete neurolinguistic assessments and
  management
• Neuroscience
• Neurology
• Neurosurgery
• Neuroanatomy
• Neuroradiology
• Neuroembryology
• Neurophysiology
• Neuropathology

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The Nervous System

• Central Nervous System (CNS)
• Brain Spinal Cord
• Peripheral Nervous System (PNS)
• Cranial Nerves (never enter spinal column)
• Spinal Nerves
• All nerves to muscles and sensory reception sites

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Terms for Fiber Tracts

• Fiber tracts like the internet sending
  information across distances
• Bundle - a group of fibers
• Column - a pillar of fibers
• Fasciculus - a small bundle
• Funiculus - a cord a cord of nerve fibers in a
  nerve trunk
• Lemniscus - a ribbon of fibers
• Tract - a large group of fibers, a pathway
• You should be familiar with primary pathways

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Organization

• CNS
• Relays incoming and outgoing messages
• Integrates Information
• Higher mental functions (language, cognition)
• Regulates

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The two hemispheres

• Left hemisphere is dominant for language and
  handedness
• Right hemisphere is dominant for music, emotion,
  and spatial processing
• Bilateral Anatomical Symmetry
• Connected by Corpus Callosum
• Unilateral Functional Differences
• Little lateralization of function at birth
• Gradual development of specialization

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Laterality and Function

• Sensory information projects to opposite
  hemisphere
• Object felt in right hand, Information processed
  by left hemisphere
• Pain felt in left foot, Information processed by
  right hemisphere
• Motor functions are also contralateral

Motor Functions
Sensory Functions
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Types of Brain Tissue

• Gray Matter The neurons or cells which have
  specialized neurologic functions (motor or
  sensory)
• White Matter Axons which form pathways for
  conducting different types of information.

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Distinct Pathways

• Connections are not random specific.
  organization of connections.
• Carry information from peripheral body parts to
  specific areas of the brain - project to
  particular cortex (outside bark) of the brain
• Each peripheral body part has a receptive area of
  the brain responsible for processing or receiving
  input
• Example visual cortex

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Plasticity of the Brain

• Brain injury is permanent, but individuals can
  show recovery.
• Plasticity refers to the brains ability to
  reorganize and modify functions and adapt to
  internal and external changes
• Important for learning
• Important for rehabilitation
• Younger brains tend to be more plastic

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How do we learn about brain function?

• Classically, examine deficits following brain
  injury, infer that damaged brain area is required
  for task.
• Today, most studies of brain function utilize
  neuroimaging techniques such as fMRI (functional
  Magnetic Resonance Imaging) or PET(Positron
  Emission Tomography) These studies usually
  focus on normal brains

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MRI scan

• This image is in radiological orientation (left
  is shown on right).
• Images can also be in neurological orientation
  (left on left)
• These structural scans can show abnormalities and
  injury.

L
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CT Scans

• CT scans use X-Rays to see inside body.
• Excellent for bone
• Often first scan in acute care (e.g. unconscious
  patient can not tell us if they have pacemaker,
  cochlear implant, or other contraindications to
  MRI).

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PET/SPECT Images

• Measures of blood flow can help determine brain
  metabolism. PET Inject radioactively labeled
  glucose.
• Note reduced uptake in posterior region.

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Combining anatomy and metabolism

• Anatomical scans (T2 MRI) have excellent spatial
  resolution.
• Metabolic scans can identify abnormalities (e.g.
  tumor).
• Combining takes advantage of complementary
  strengths

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Relative Coordinates

• On the globe we talk about North, South, East and
  West.
• Lets explore the coordinates for the brain.

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Orientation

• Human anatomy described as if person is standing
• If person is lying down, we would still say the
  head is superior to feet.

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Orientation - animals

• Dorsalback

Dorsal
Rostral
Caudal
Ventral

• Cranialhead
• Rostralbeak

• Caudaltail

• Ventralbelly

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Coordinates Dorsal Ventral

• Human dorsal/ventral and rostral/caudal differ
  for brain and spine.
• Head/Foot, Superior/Inferior, Anterior/Posterior
  not ambiguous.

Dorsal Ventral
Superior Inferior
Dorsal Ventral
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Coordinates Human

• Human dorsal/ventral and rostral/caudal differ
  for brain and spine.
• Head/Foot, Superior/Inferior, Anterior/Posterior
  not ambiguous.

C
R
R
R
C
Posterior
Anterior
C
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Anatomy Relative Directions
lateral lt medial gt lateral
Posterior ltgt Anterior
Ventral/Dorsal aka Inferior/Superior aka Foot/Head
Ventral ltgt Dorsal
Anterior/Posterior aka Rostral/Caudal
Posterior ltgt Anterior
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Coordinates - Anatomy

• 3 Common Views of Brain
• Coronal (head on)
• Sagittal (profile)
• Axial (birds eye), aka Transverse. The book
  calls this Horizontal but it is not horizontal
  when we are lying in a scanner.

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Coronal

• Corona crown a coronal plane is parallel to
  crown that passes from ear to ear
• Coronal cut creates anterior, posterior portions

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Transverse

• Transverse perpendicular to the long axis
• These cuts are also referred to as Axial.

Example cucumber slices are transverse to long
axis.
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Sagittal

• Sagittal arrow like
• Sagittal cut divides object into left and right
• sagittal suture looks like an arrow.

top view
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Sagittal and Midsagittal

• A Sagittal slice down the midline is called the
  midsagittal view.

midsagittal
sagittal
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Oblique Slices

• Slices that are not cut parallel to an orthogonal
  plane are called oblique.
• The oblique blue slice is neither Coronal nor
  Axial.

Cor
Oblique
Ax
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Distance from midline

• Medial near sagittal midlineOptic chiasm C
  medial of eyes
• Lateral far from sag. MidlineEyes are lateral
  of optic chiasm
• Ipsilateral same sideDamage to A will cause
  blindness in ipsilateral eye
• Contralateral different sideDamage to D will
  lead to a contralateral field cut.
• Note after brain injury (lesions) we talk about
  contralesional and ipsilesionalDamage to visual
  cortex G leads to problems with contralesional
  vision.

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Relative positions

• Distance From Body
• Proximal, Central near center of body
• Think proximity
• Shoulders are proximal parts of arms
• Distal,peripheral away from body
• Think distant
• Fingers are distal parts of the arms
• Distance from Surface
• Superficial, external near surface
• The bump bruised superficial tissue.
• Profound, deep far from surface
• The car crash injured deep organs.

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Movements
Flexion
Extension - Increasing angle between two body
parts (-Flexion). Adduction - Pulls body part
toward midline (-Abduction) Pronation - A
rotation of the forearm that moves the palm from
an anterior-facing position to a posterior-facing
position (-Supination)
Supination
Pronation
Extension
Abduction
Adduction
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Types of cells in the brain

• Neuron Cell which is responsible for receiving,
  transmitting and synthesizing information
• cell body contains organelles for metabolism and
  a nucleus
• Glial Cells Support cells for Neurons (CNS
  oligodendrocytes, astrocytes, ependymal cells,
  radial glial PNS Satellite and Schwann cells)

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Neuron Types

• Neurons come in different types some only
  communicate locally, while others have very long
  axons that communicate with distant regions.

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Glial Cells

• Glial cells have crucial functions
  www.mult-sclerosis.org/glialcells.html
• Repair, maintenance and cleaning. They produce
  new myelin when it become damaged, lay down scar
  tissue, and remove dead cells and other debris.
• Physical support. They have hairlike filaments
  which hold the neurons in place and allow the
  central nervous system to retain its structural
  integrity.
• CNS development. Help migration of neurons.
• Chemical regulation. Supply chemicals such as
  potassium and calcium and regulate
  neurotransmitter levels.
• Ten times as many glial cells as neurons

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Multiple choice

• Why is the difference between a tumor and a
  cancer?
• Cancer involves neurons, tumors involve other
  cells (e.g. glial cells).
• Tumor involves neurons, cancer involves other
  cells (e.g. glial cells).
• Tumor is due to virus, cancer is due to bacteria
• A tumor can be benign, pre-malignant or
  malignant, whereas cancer is by definition
  malignant.

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Tumors

• Tumor from the Latin "swelling
• In medicine, swelling due to abnormal,
  uncontrolled cell division
• Brain tumors are usually due to glial cells
  (gliomas).
• Glial cells more common, so higher probability of
  cell becoming cancerous.
• Neurons usually stop dividing earlier.

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The Central Nervous System

• Telencephalon (Cerebrum)
• Cortex
• Basal Ganglia
• Diencephalon
• Thalamus
• Hypothalamus)
• Mesencephalon (Midbrain)
• Colliculi
• Substancia Nigra
• Rhombencephalon
• Cerebellum
• Pons
• Medulla

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Deep Structures

• Basal Ganglia Initiates movements
• Caudate nucleus, Putamen,Globus pallidus
• Diencephalon
• Thalamus Relay from body to cortex
• Hypothalamus and pituitary gland Regulation
  (e.g. hormone secretion)

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Deep Structures

• Basal Ganglia Initiates movements
• Caudate nucleus(red)
• Putamen (green)
• Globus pallidus (blue)
• Diencephalon
• Thalamus (yellow)
• Hypothalamus (not shown)

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Brain Stem

• Midbrain
• Early auditory/visual processing
• Dopamine for movement control
• CN III and IV emerge
• Pons
• CN V, VI, VII VIII
• Medulla Oblongata
• Pyramidal decussation nerves from left cross to
  right side and vise versa
• CN IX, X, XI, XII

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The cortex

• Cortex Bark shell of brain mostly gray
  matter
• 80 of human brain
• 20 of squirrel brain

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Multiple choice

• What does temporal usually refer to?
• Space.
• Color.
• Time.
• Loudness.

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Multiple choice

• Why is it called the temporal lobe?
• This area handles memory remembering previous
  times.
• This lobe processes hearing hearing requires
  good temporal precision.
• This lobe is under the temples, where the hair
  turns gray early in life.
• This area helps with counting which we use for
  timing events.

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Cortical folding

• Cortical folding increases surface area.
• Ridges are called Gyri (singular Gyrus)
• Greek gyros circle, hence a coil of brain
  cortex
• Valleys are called Sulci (singular Sulcus).
• Latin a groove.

Gyri Sulci
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Gray and White Matter

• The outer surface of the cortex is gray matter
  lots of interconnected neurons (like cities)
• Underneath is the white matter the highways
  connecting regions.

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Functional Classifications

• Some neurons transmit general information
• Pain and Temperature
• Originate in surface structures
• Other neurons transmit specialized information
• Specialized receptors
• Hearing and vision
• Somatic Skeletal muscles
• Visceral Refer to internal vital body organs
• Can be either
• Afferent Sensory
• Efferent Motor

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Cortical layers

• Neurons are in six layers
• I. Molecular layer
• II. External granular layer
• III. External pyramidal layer
• IV. Internal granular layer
• V.Internal pyramidal layer
• VI. Fusiform layer
• Functions
• Superficial layers (I-III) inter-cortical
  connections
• IV input from thalamus
• V,VI outputs to leave cortex

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The big folds

• The folds of your brain are like a fingerprint
  there are a few general patterns, with individual
  variability.
• Two main folds
• Central SulcusFissure of RolandoRolandic sulcus
• Lateral sulcusSylvian fissure

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Describing cortex location

• Brodmann Areas (BAs, 1909)
• Appearance of cortex under microscope
• Not necessarily function
• Arbitrary numbers are hard to remember
• Some are crucial for a speech pathologist
• 44 Brocas Area
• 22 Wernickes Area

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Brodmann Areas (medial slice)

• Note that gray matter is located in the
  longitudinal fissure (between the two hemispheres)

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Cortical Names

• Much of cortex referred to by combination of
  coordinatelobegyrus
• E.G. Superior Temporal Gyrus (STG)
• Middle Temporal Gyrus(MTG)
• Lateral Occipital Gyrus (LOG)

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Cortical names

• Tip of an object called a pole
• Frontal Pole
• Temporal Pole

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Sulci names

• Many of sulci referred to by combination of
  coordinatelobesulcus
• Superior temporal sulcus (STS)
• Inferior frontal sulcus (IFS)
• Precentral and postcentral sulciare just
  anterior and posterior to the central sulcus.

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Brain function

• Anatomy is interested with the structure of an
  organism.
• Physiology is interested in the function of the
  structure.
• We are still learning about brain function
• Modern maps of brain function are primitive

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Brain function

• Much of the primate cortex devoted to vision.
• In some monkeys, up to 50 of neocortex is
  devoted to vision.

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Brain function

• Two striking features of human brain
• Lots of cortex left over (yellow) not devoted
  to specific task we are flexible
• Not much of the cortex is solely devoted to
  language.