The document provides information on the functional anatomy and physiology of the nervous system. It discusses: 1. The three main functions of the nervous system: sensory input, integration, and motor output. 2. The structural classification of the central nervous system (CNS) which includes the brain and spinal cord, and the peripheral nervous system (PNS) which includes nerves outside the CNS. 3. The organization and components of the nervous system including neurons, neuroglia, the CNS, brain regions and lobes, motor and sensory homunculi, and protection of the CNS by structures like the meninges and cerebrospinal fluid.

1. Functional Anatomy & Physiology
Dr. Ra’ed Ahmed
MBChB, FIBMS
Neurologist March 31 - 2015
Lec. 1
09.00 AM
1

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
3

4. Organization of the Nervous System
4

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)
5

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
6

7. Nervous Tissue: Support Cells
 Oligodendrocytes
(CNS)
Produce myelin
sheath around
nerve fibers in the
central nervous
system
7

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
8

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
9

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
12

13. Regions of the Brain
 Cerebral
hemispheres
 Diencephalon
 Brain stem
 Cerebellum
13

14. Lobes of the Brain
14

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.
19

20. Motor Homunculus
20

21. Sensory Homunculus
21

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
22

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
23

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
25

26. Diencephalon
Figure 7.15
26

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.
27

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
29

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
31

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
32

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
35

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).
38

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.
40

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
42

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
44

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
76