PTA 150 Day 1 Neuroanatomy

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Transcript PTA 150 Day 1 Neuroanatomy

Concorde Career College
Physical Therapist
Assistant
PTA 150: Fundamentals of Treatment II
DAY 1
Neuroanatomy Review
Functions of the Nervous System
 Coordinates all body systems
 Detects and responds to stimuli
 Brain & spinal cord act as switching centers
 Nerves carry messages to and from centers
Anatomical Divisions
 Central Nervous System (CNS)
• Brain
• Spinal cord
 Peripheral Nervous System (PNS)
• Cranial nerves
• Spinal nerves
• Peripheral Nerves
• Receptors detecting sensory stimuli
Anatomical
Divisions of the
Nervous System
Anatomical
divisions of the
nervous system
Physiological Divisions
 Somatic Nervous System:
 Controlled voluntarily
 Composed of all receptors & nerves which innervate
the skin and muscles
 Autonomic (visceral) Nervous System (ANS):
 Controlled involuntarily
 Effectors are smooth & cardiac muscle and glands
 Controls homeostasis & responds to stress
 Subdivided into:
• Sympathetic nervous system
• Parasympathetic nervous system
Building Blocks of the
Nervous System
 Neuron
 Excitable cells that
receive and send
signals to other
excitable cells
 Composed of a cell
body (soma), dendrites
and an axon
Types of Neurons
 Sensory = Afferent
 Conduct impulses to spinal cord, brain
 Motor = Efferent
 Conduct impulses to muscles, glands
 Interneurons
 Central or association neurons
 Conduct information within CNS
Building Blocks of the
Nervous System
 Neuroglia
 Non-excitable support cells
 Functions:
• Formation of myelin
• Guidance of developing neurons
• Maintenance of extracellular ion levels
• Reuptake of chemical transmitters following neuronal
activity
 Types include astrocytes, oligodendrocytes,
Schwann cells, microglia
Grouping of Neural Tissue
 Nerve
 Grouping of neurons outside the CNS
 May be carrying impulses either toward or away from
the CNS
 Tract
 Grouping of neurons within CNS
 Ganglia
 Grouping of neuron cell bodies outside CNS
Grouping of Neural Tissue
 White Matter
 Myelinated axon from many neurons
 Gray Matter
 Cell bodies and dendrites and/or unmyelinated axons
 Upper Motor Neuron
 Brain & spinal cord
 Lower Motor Neuron
 Peripheral nerve
What name is given to nerves
that convey impulses toward
the CNS, and what name is
given to nerves that transport
away from the CNS?
Q&A
Brain
&
Spinal Cord
The Central Nervous System
Distinct Areas of The Brain
 Cerebrum
 2 Cerebral hemispheres
 Longitudinal fissure
 Lobes
 Brain stem
 Midbrain
 Pons
 Medulla oblongata
 Diencephalon
 Thalamus
 Hypothalamus
 Cerebellum
The Cerebral Hemispheres
 Lobes
 Frontal
 Parietal
 Temporal
 Occipital
 Cerebral Cortex
 Gyri
 Sulci
 Corpus Callosum
 Deeper Brain
Structures:
 Diencephalon
• Thalamus
• Hypothalamus
 Basal Ganglia
 Internal Capsule
Landmarks of the
superior surface
External surface of the brain,
superior view. The division into
two hemispheres and into lobes
is visible
Frontal Lobe
 Motor cortex – responsible for voluntary movement
on the contralateral side
 Broca’s Area – controls motor component of
speech
 Responsible for cognitive functions – judgment,
attention, mood, abstract thinking & aggression
 Damage may result in: paralysis, loss of flexibility
in thinking, changes in personality, difficulty with
language expression
Parietal Lobe
 Sensory Cortex – incoming sensory information
from the contralateral side is processed and given
meaning
 Perceives touch, pain, temperature, PPC
 Short term memory
 Damage may result in difficulty with naming an
object (anomia), writing, reading, math, eye-hand
coordination or a lack of body awareness
Temporal Lobe
 Auditory Cortex – receives & processes auditory
info
 Wernicke’s area – comprehension of spoken word
 Long-term memory
 Visual perception
 Primary visual cortex
 Damage may result in: difficulty understanding
spoken word, recognizing faces, memory &
increased aggression
Occipital Lobe
 Primary visual cortex – processing and
interpretation of visual information
 Damage may result in: visual deficits, visual
hallucinations and illusions, and difficulties with
reading and writing, locating objects & recognizing
colors
Functional areas of the cerebral
cortex
Corpus Callosum
 Largest anatomical connection for hemispheric
communication
 Made up of axons, white matter
Deeper Brain Structures
 Diencephalon
 Thalamus
• Sorts sensory impulses
• Directs impulses within cerebral cortex
 Hypothalamus
• Maintains homeostasis
• Controls sympathetic and parasympathetic divisions of
autonomic nervous system
• Influences heartbeat, blood flow, hormone secretion
Regions of the Diencephalon
Deeper Brain Structures
 Basal Ganglia (BG)
 Responsible for regulation of posture and muscle
tone
 Exerts effects on motor planning areas of cortex
 Parkinson’s Disease results from BG degeneration
 Internal Capsule
 Made up of axons traveling to & from the cortex,
brain stem and spinal cord
 Has an anterior and posterior limb, each containing
axons from specific nerve tracts
The Brain Stem
 Connects cerebrum and diencephalon with the
spinal cord
 Composed of:
 Midbrain
 Pons
 Medulla oblongata
The Brainstem: Midbrain
 Superior part of brain stem
 Four masses form superior part of midbrain
 Reflexes involving eyes and ears
 Conducts impulses between higher centers of
cerebrum and lower centers of pons, medulla,
cerebellum, spinal cord
The Brainstem:
Pons
 Connecting link between cerebellum and rest of
nervous system
 Some reflexes involving respiration
The Brainstem:
Medulla Oblongata
 Respiratory center
 Cardiac center
 Vasomotor center
 Contralateral (opposite side) control
 Decussation of the pyramids
 Crossing of the descending cortico-spinal tract tracts
in the medulla oblongata
The Cerebellum
 Three parts
 Vermis
 Left hemisphere
 Right hemisphere
 Functions
 Help coordinate voluntary
muscles
 Help maintain balance
 Help maintain muscle tone
The Cerebellum:
Vermis
Imaging Studies of the Brain
 Imaging techniques to study the brain without
surgery
 Computed tomography (CT) scan
 Magnetic resonance imaging (MRI)
 Positron emission tomography (PET)
 Electroencephalograph (EEG)
CT Scan
http://midgetwrangler.files.wordpress.com/2008/11/ctscan.jpg
http://www.crash.lshtm.ac.uk/Other%20Docs/normal.jpg
MRI
http://www.tcd.ie/courses/images/neuroscience/03.jp
g
http://www.prevenium.com/images/full_body_mri_scan.gif
PET Positron Emission
Tomography
http://www.kuakini.org/Kuakini/uploadedimages/PET%20
Scan.gif
http://www.capersonalinjurycaselawnotes.com/uploads/image/PET%20scan.j
pg
Electroencephalograph
 Record electric currents given off by brain nerve
cells
 Study sleep patterns
 Diagnose disease
 Locate tumors
 Study drug effects
 Determine brain death
Functions of the Spinal Cord
 Links the brain and the PNS
 Direct continuation of the brainstem (medulla)
 Contained in and protected by vertebrae
 2 major functions:
 Communication of sensory information
 Communication & coordination of motor information
and movement patterns
Spinal Cord & Spinal
Nerves
Nerve plexuses (networks) are
shown:
A. Lateral view B. Posterior
view
Structure of the Spinal Cord
 Unmyelinated tissue (gray matter)
 Dorsal horn
 Ventral horn
 Gray commissure
 Central canal
 Myelinated axons (white matter)
 Posterior median sulcus
 Anterior median fissure
 Ascending (sensory) and descending (motor) tracts
 (A) Cross-section of the
spinal cord showing the
organization of the gray and
white matter. The roots of
the spinal nerves are also
shown. (B) Microscopic view
of the spinal cord in crosssection (x5).
Diseases & Disorders: Spinal
Cord
 Injuries - Defined
 Monoplegia: paralysis of a single limp
 Diplegia: similar paralysis of body parts (two arms,
two legs.
 Paraplegia: paralysis of lower body
 Hemiplegia: paralysis of half the body
 Tetraplegia: (quadriplegia)
Aging of the CNS
 Decreased brain size and weight
 Decreased speed of information processing
 Slowed movements
 Diminished memory
 Reduced blood flow to brain
Aging of the Nervous System
Physiologic Change
Functional Effect
Nerve cell degeneration and
decrease in cerebral blood
flow
(about 20% reduction
between ages 50-80)
Reduced response time and
decreased reflexes; loss or
increased sensitivity to pain,
which increases injury risk;
decreased tolerance to heat
or cold; decreased balance
and coordination; altered
gait
Decrease in
neurotransmitters
Increased potential for
dementing processes
From: Stillerman (Ed), Modalities for Massage and Bodywork, Elsevier, St
Louis, 2008, in press.
Cranial Nerves
Spinal Nerves
Peripheral Nerves
Receptors
Peripheral Nervous System
12 pairs of cranial nerves as
seen from the base of the brain
The Cranial Nerves
 Olfactory (I)
 Facial (VII)
 Optic (II)
 Vestibulocochlear (VIII)
 Oculomotor (III)
 Glossopharyngeal (IX)
 Trochlear (IV)
 Vagus (X)
 Trigeminal (V)
 Accessory (XI)
 Abducens (VI)
 Hypoglossal (XII)
The Spinal Nerves
 31 pairs, named by the respective vertebrae
 Cauda Equina
 2 roots branch from the spinal cord to form the
spinal nerve
 Dorsal root – carries sensory info
 Ventral root – carries motor info
 Spinal nerve splits into 2 rami
 Dorsal rami – innervate deep mm & skin of the back
 Ventral rami – innervate superficial back, lateral and
anterior trunk & extremity muscles
Branches of the Spinal Nerves
 Cervical plexus (C1 – C5)
 Phrenic nerve
 Brachial plexus (C5 – T1)
 Axillary nerve
 Musculocutaneous nerve
 Radial nerve
 Median nerve
 Ulnar nerve
 Lumbosacral plexus (L1- S3)
 Sciatic nerve
 Dermatomes
A dermatome is a region of the skin
supplied by a single spinal nerve.
Peripheral Nerves
 Contain efferent (motor) fibers
 Originate in the ventral horn
 Contain large cell body, dendrites and axon
 Axon becomes part of peripheral nerve & innervates
motor end plate in muscle
 Contain afferent (sensory) fibers
 Dendrite originates as receptor in skin, mm or tendon
 Dendrite travels to cell body in the dorsal horn
 Cell body sends impulse along axon to the spinal
cord or synapses to the ascending tract
Receptors
 Communicate information from the external world
and the internal body to the CNS
 Most respond to one form of stimulus
 Mechanical, chemical or thermal
 Distributed over the body surface, in the
musculoskeletal system and in the viscera
Distribution of Sense Receptors
 Special Senses & Receptors
 Vision, Hearing, Equilibrium, Taste, Smell
 Impulses are transmitted through cranial nerves
 Cutaneous Receptors
 Pressure, temperature, pain, touch, stretch
Distribution of Sense Receptors
 Proprioceptors
 Sense body position
 Made up of muscle spindle,
Golgi Tendon Organs (GTO),
and joint receptors
 Located in mm, tendons, joints
 Relay impulses of body parts in
relation to each other
 Send impulses to the
cerebellum for coordination
Sensory Adaptation
 Occurs when receptors are exposed to continuous
stimulus
 Some receptors can adjust themselves so
sensation becomes less acute
 Receptors adapt at different rates
 Pain receptors do not adapt
Functions of the Autonomic
Nervous System
 Regulates the action of glands, smooth muscles of
hollow organs and vessels, and heart muscle
 Preganglionic neuron connects spinal cord to
ganglion
 Postganglionic neuron connects ganglion to
effector
Divisions of the ANS
 Sympathetic Nervous System
 Fight-or-flight response
 Thoracolumbar area, Collateral ganglia, Adrenergic
 Parasympathetic Nervous System
 Returns body to normal
 Craniosacral, Terminal ganglia, Cholinergic
 Systems generally have opposite effects on organ
Autonomic Nervous
System
The diagram shows only one
side of the body for each division
Questions
Resources
 Functional Neurorehabilitation through the
Lifespan. Bertoti, D. F.A. Davis. 2004. Chapter 2
 PTA Exam, The Complete Study Guide, Scott M.
Giles, 2011; Scorebuilders. Chapter 2