dr raad nero med

1. Functional Anatomy & Physiology
Dr. Ra’ed Ahmed
MBChB, FIBMS
Neurologist March 31 - 2015
Lec. 1
09.00 AM
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2. Functions of the Nervous System
1. Sensory input – gathering information
To monitor changes occurring inside and
outside the body (changes = stimuli).
2. Integration –
to process and interpret sensory input
and decide if action is needed.
3. Motor output
A response to integrated stimuli.
The response activates muscles or glands.2

3. Structural Classification of the Nervous
System
 Central nervous system (CNS)
Brain
Spinal cord
 Peripheral nervous system (PNS)
Nerve outside the brain and spinal cord
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4. Organization of the Nervous System
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5. Nervous Tissue: Support Cells (Neuroglia or
Glia) of CNS
 Astrocytes (largest of neuroglia)
 Abundant, star-shaped cells
 Brace neurons
 Form barrier
between capillaries
and neurons
 Control the chemical
environment of
the brain (CNS)
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6. Nervous Tissue: Support Cells
 Microglia (CNS)
 Spider-like phagocytes
 Dispose of debris
 Ependymal cells
(CNS)
 Line cavities of the
brain and spinal cord
 Circulate
cerebrospinal
fluid
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7. Nervous Tissue: Support Cells
 Oligodendrocytes
(CNS)
Produce myelin
sheath around
nerve fibers in the
central nervous
system
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8. Support Cells of the PNS
 Satellite cells
Protect neuron cell bodies
 Schwann cells
Form myelin sheath in the peripheral
nervous system
Figure 7.3e
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9. Neuron Anatomy
Slide 7.9b
 Cell body : nucleus
large nucleolus
 Dendrites – conduct
impulses toward the
cell body
 Axons – conduct
impulses away from
the cell body
Figure 7.4a
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10. 10

11. Central Nervous System (CNS)
 CNS develops from the embryonic
neural tube
The neural tube becomes the
brain and spinal cord
The opening of the neural tube
becomes the ventricles
Four chambers within the brain
Filled with cerebrospinal fluid 11

12. Brain
 Part of CNS that lies within the cranial
vault, the encephalon.
 Its hemispheric surface is convoluted and
has gyri and sulci
 Weighs 350 g in the newborn and 1400 g
in the adult.
 The male brain is on average slightly
heavier than the female brain
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13. Regions of the Brain
 Cerebral
hemispheres
 Diencephalon
 Brain stem
 Cerebellum
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14. Lobes of the Brain
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15. Frontal lobes:
• Reasoning,abstraction,concentration
• Control of voluntary eye
movements.
• Motor control of speech in the
dominant hemisphere.
• Motor Cortex
• Urinary continence.
• Emotion and personality

16. Parietal lobes:
• Sensory cortex – define size,
weight, texture and consistency
(contralateral).
• Sensation is localised, and
modalities of touch, pressure and
position are identified.
• Awareness of the parts of your body.
• Dominant is involved in ideomotor
praxis
• Non-dominant – visuospatial
information

17. Temporal lobes:
• Primary auditory receptive areas.
handle visual perception and olfaction.
• Learning and memory, emotional
affect.
• Dominant temporal lobe influences
comprehension of speech.
• Nondominant temporal lobe
mediates prosody and spatial
information

18. Occipital lobes:
• Primary visual cortex.
• Visual association areas.
• Visual perception.
• Some visual reflexes (i.e. visual
fixation).
• Involuntary smooth eye movements

19. Brodmann’s areas : mapping the cortical areas
of the brain.
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20. Motor Homunculus
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21. Sensory Homunculus
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22. Layers of the Cerebrum
 Gray matter
Outer layer
Composed
mostly of
neuron cell
bodies
 White matter
Fiber tracts
inside the gray
matter
Figure 7.13a
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23. Basal Ganglia
 large masses of gray matter deep within
the cerebral hemispheres.
 Include the caudate, putamen, and
globus pallidus that lie lateral to the
thalamus.
 Functionally, substantia nigra (SN) and
the subthalamic nucleus.
 Motor control includes the preparation for
and execution of cortically initiated
movement
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24. 24

25. Diencephalon
 Sits on top of the brain stem
 Enclosed by the cerebral hemispheres
 Made of four parts
Thalamus
Hypothalamus
Epithalamus (roof of the third ventricle
Houses the pineal body, choroid plexus)
Subthalamus
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26. Diencephalon
Figure 7.15
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27. Thalamus
 Surrounds the third ventricle.
 The relay station for sensory impulses.
 Transfers impulses to the correct part of
the cortex for localization and
interpretation.
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28. Hypothalamus
 Under the thalamus.
 Important autonomic nervous system
center
Helps to regulate body temperature
Controls water balance
Regulates metabolism, appetite control.
An important part of the limbic system
(emotions) 28

29. Brain Stem
 It is a small, narrow region connecting
the spinal cord with the rest of the brain
 Parts of the brain stem
Midbrain
Pons
Medulla oblongata
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30. Brainstem
30

31. Midbrain
 located between the diencephalon
and the pons.
 Mostly composed of tracts of nerve
fibers
Reflex centers for vision and hearing
Cerebral aquaduct – 3rd-4th ventricles
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32. Pons
 pons means “bridge” in Latin
 The bulging center part of the brainstem
 Mostly composed of fiber tracts
 Includes nuclei involved in the control of
breathing
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33. Medulla Oblongata
 The lowest part of the brain stem
 Merges into the spinal cord
 Includes important fiber tracts
 Contains important control centers
Heart rate control
Blood pressure regulation
Breathing
Swallowing
Vomiting 33

34. 34
Cranial nerves on the anterior surface of the
brain.

35. Cerebellum or "small brain"
 Located in the posterior cranial fossa
 Attached to the brainstem by three
cerebellar peduncles
 Forms the roof of the fourth ventricle
 Anatomically divided into the two
hemispheres, the midline vermis and the
flocculonodulus ,consists of folia and
fissures on its surface
 Provides involuntary coordination of body
movements
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36. 36

37. Protection of the Central Nervous System
 Scalp and skin
 Skull and vertebral column
 Meninges
 CSF
 BBB
37

38. SKULL
 22 bones in total, 8 make up the cranium,
other 14 facial bones.
 Cranium is that part of the
skull that encloses the brain
 3 components within
the cranium have a balance
(80% brain ,
10% blood ,10% CSF).
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39. Meninges
 Dura mater " hard mother"
Double-layered external covering
Periosteum – attached to surface of the
skull
Meningeal layer – outer covering of the
brain
Folds inward in several areas (falx
cerebri, tentorium cerebelli & falx
cerebelli) 39

40. Meninges
 Arachnoid layer " spider"
Middle layer ,extremely thin ,
nonvascular
Web-like, loosely encloses the brain
 Pia mater:
 Inner most, delicate highly vascular
 Intimately adhere to the brain substance
 Spaces of the meninges: extradural,
subdural and subarachnoid.
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41. Cerebrospinal Fluid CSF
 Similar to blood plasma composition
 Formed by the choroid plexus
 Reabsorbed into the venous blood
flow via the arachnoid villi
 Produces at a rate (~ 500mL/day) and
total volume (~ 150mL)
 Buoyancy , Protection ,Transport of
nutrients, Removal of waste products 41

42. Ventricles and Location of the
Cerebrospinal Fluid
Figure 7.17b
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43. 43

44. Spinal Cord
 Continuous with the
medulla oblongata at the
spinomedullary junction
terminates caudally as
conus medullaris.
 Ends at the level of lower
border of L1
 Enlargements occur in the
cervical and lumbar
regions
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45. Spinal Cord cont.
 lies within subarachnoid space and covered by
three meningeal coats (pia , arachnoid and dura
mater).
 Averges, in length, 45 cm in males and 42 cm in
females
 Weighs about 30 g , comprising 2% of the adult
brain weight
 The spinal cord comprises
31 segments defined by
31 pairs of spinal nerves 45

46. PNS : Spinal Nerves
Figure 7.22a 46

47. APPROACH TO THE PATIENT
WITH NEUROLOGIC DISEASE
 Where is the lesion?
 What is the lesion?
 Meridians of Longitude= motor, sensory
pathways (location, function, decussation)
–Corticospinal
–Spinothalamic
–Dorsal column – Medial Lemniscus
 Parallels of Latitude( Cortex---muscle)

48. What are the most important
regions for anatomic localization?
 Cortical Brain
 Subcortical Brain
 Brainstem
 Cerebellum
 Spinal Cord
 Root
 Peripheral Nerve
 Neuromuscular Junction
 Muscle

49. How are symptoms localized to
these neuroanatomic regions?
Neurologic Examination:
1- Higher Cortical Function
2- Cranial Nerves
3- Cerebellar Function
4- Motor
5- Sensory
6- Deep Tendon Reflexes
7- Pathologic Reflexes

51. Characteristic of upper motor
neurone lesions: UMNL
 • No wasting, but from disuse;
 • Increased tone “Spasticity” of clasp-knife
type;
 • Weakness most evident in anti-gravity
muscles;
 • Increased reflexes and clonus;
 • Extensor plantar responses.

52. Characteristics of lower motor
neurone lesions: LMNL
 • Wasting “pronounced” ;
 • Fasciculation;
 • Decreased tone (i.e. flaccidity);
 • Weakness;
 • Decreased or absent reflexes;
 • Flexor plantar responses.

54. Corticospinal Tracts

55. Pain & Temperature

56. Position sense
• Ataxia or clumsiness of
movement
• Partial compensation by
active monitoring of
movement by the eyes;
• No weakness.

57. Patterns of sensory deficit

58. Clinical features of Cortical Brain
lesion
 Dominant (usually left) hemisphere is “aphasia”
 Nondominant (usually right) hemisphere,
usually causes visual-spatial problems.
 Cortical sensory loss such as two-point
discrimination, stereognosis, and
graphesthesia.
 Seizures are almost always cortical in origin.
 Incomplete hemiparesis, affecting the face and
arm, but not the leg.

61. Clinical features of Subcortical
Brain lesion
 Higher Cortical Function: normal
 Cranial Nerves: visual field cuts
 Cerebellar Function: usually normal
 Motor: weakness in face=arm=leg ,UMNL
 Sensory: sensory abnormalities in
face=arm=leg
 Deep Tendon Reflexes: hemi-hyper-reflexia
 Pathologic Reflexes: extensor planter reflex

62. Clinical features of Brainstem
disease
The brain stem is essentially the spinal cord with
embedded cranial nerves.
 Cranial nerve signs: diplopia, decreased
strength or sensation over the face, dizziness,
deafness, dysarthria, dysphagia
 Long tract signs: hemiparesis UMNL or
hemisensory loss
 Crossed signs or Bilateral findings

64. Clinical features of Cerebellar
disease
A. Incoordination of muscle activity:
 • in the head: nystagmus, dysarthria;
 • in the arms: finger–nose ataxia, kinetic
(intention) tremor, difficulty with rapid alternating
movements (dysdiadochokinesia);
 • in the legs: heel–knee–shin ataxia, gait ataxia,
falls.
B. Hypotonia ,no Weakness, Sensory: normal
DTRs normal ,Pathologic Reflexes: none

67. Clinical features of Spinal cord
disease
 Atriad of symptoms (Sensory level,Spastic
weakness & Bowel and bladder problems)
 Distal weakness greater than proximal
weakness (UMN signs below the lesion)
 Increased tone (spasticity)
 Increased reflexes ,Clonus
 Extensor plantar response
 Absent superficial reflexes
 No significant atrophy or fasciculations

69. Clinical features of Root diseases
(Radiculopathies)
 Pain is the hallmark of root disease
 Weakness, while asymmetric, may be either
proximal or distal, depending on which roots are
involved
 O E = LMN findings
 Atrophy and fasciculations.
 Tone is normal or decreased, and hypo- to a-
reflexia if the root carries a reflex.
 Sensory loss occurs in a dermatomal

72. Clinical features of Peripheral
neuropathies
 Weakness leg, arm : distal predominant
 Sensory changes : distal predominant
 OE
 Distal, often asymmetric weakness with atrophy,
fasciculations
 Muscle tone is often decreased. loss of distal
reflexes, Mute responses to plantar stimulation
 Sensory loss

73. Clinical features of Neuromuscular
junction disease
 “Fatigability” “Fluctuation” the hallmark of
NMJ
 Proximal symmetric weakness
 Weakness is often extremely proximal,
involving muscles of the face, eyes
(ptosis), and jaw.
 Muscles are normal in size, without
atrophy or fasciculations, with normal tone
and reflexes.
 No sensory loss.
 positive response to anticholinesterase.

74. Clinical features of Muscle disease
 Proximal symmetric leg & arm weakness
without sensory loss.
 OE
 Muscles : normal in size, without atrophy
 no fasciculation;
 Tone : normal or reduced;
 Reflexes : normal or reduced.

75. what is the lesion?

76. Happy Reading !
THANK YOU
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