This document provides an overview of clinical neuroanatomy and disorders of the nervous system. It begins by explaining why the study of the nervous system is important for understanding neurological diseases. It then outlines the functional and anatomical subdivisions of the nervous system. The remainder of the document discusses various neurological disorders categorized by the areas of the nervous system they affect, such as the peripheral nerves, neuromuscular junction, brainstem, basal ganglia, cerebellum, and memory/cognition. Examples of specific diseases are provided for each category.

1. Clinical Neuroanatomy
Prof. Vajira Weerasinghe
Professor in Neurophysiology, Faculty of Medicine,
University of Peradeniya
& Consultant Neurophysiologist, Teaching Hospital, Peradeniya
www.slideshare.net/vajira54

2. Why study nervous system?
• Neurological diseases are very disabling and very little
treatment is available
• Understanding the structure and function of the
nervous system helps to understand the
pathophysiological basis of these diseases

4. Functional Subdivisions
• Sensory functions
 feeling, eg. pain
• Motor functions
movement, eg. walking
• Integrative functions
eg. reflexes
• Autonomic functions
control of blood pressure
• Higher functions
memory, learning

5. Anatomical Subdivisions
• Central Nervous system
Brain and spinal cord
• Peripheral Nervous system
Cranial Nerves & Peripheral Nerves
• Autonomic system
sympathetic & parasympathetic

6. Disorders of the nervous system
based on an anatomical divisions
Type of disorder example
1. Peripheral neuropathies
1. Polyneuropathies diabetic polyneuropathy
2. Mononeuropathies carpal tunnel syndrome
2. Neuromuscular junction disorders
1. Presysnaptic disorders botulism
2. Postsynaptic disorders myasthenia gravis
3. Anterior horn cell diseases MND (motor neuron disease)
4. Plexus, spinal root or spinal cord disorders Erb’s palsy, cervical
spondylosis, intervertebral disc
prolapse
5. Brainstem disorders Tumors
6. Strokes CVA
7. Basal ganglia disorders Parkinsonism
8. Cerebellar disorders Cerbellar ataxia
9. Memory and cognitive function disorders Alzheimer Disease
10. Cranial nerve lesions Bell’s palsy
11. Others Multiple sclerosis

7. Peripheral neuropathies
• Peripheral nerves are affected
• Types: Polyneuropathies or mononeuropathies
• Components: Sensory, motor, autonomic or mixed
• Distribution: Symmetrical or asymmetrical
• Cause: Trauma, demyelination, degeneration
• Examples:
 Diabetes mellitus
 vitamin deficiency
 alcoholism
 carpal tunnel syndrome
 ulnar nerve lesions
 wrist drop
 foot drop
 tarsal tunnel syndrome

10. NMJ disorders
• Myasthenia gravis
 Antibodies to Ach receptors
 Post synaptic disorder
• Lambert Eaton Syndrome (myasthenic syndrome)
 Presynaptic disorder (antibodies against Ca channels)
• Botulism
 Presynaptic disorder
 Binds to the presynatic region and prevent release of Ach

11. NMJ disorders
• Snake venom (Presynaptic or postsynaptic disorder)
Krait (bungarotoxin)
Postsynaptic disorder
Cobra
Postsynaptic disorder
Russell’s viper
Presynaptic disorder

12. Snake venom
• Common Krait (bungarus
caeruleus)
Produces neurotoxin known as
bungarotoxin
Very potent
Causes muscle paralysis and death if not
treated
• Cobra
 venom contain neurotoxin

13. Myasthenia gravis
• Serious neuromuscular disease
• Antibodies form against acetylcholine nicotinic
postsynaptic receptors at the NMJ
• Characteristic pattern of progressively reduced muscle
strength with repeated use of the muscle and recovery of
muscle strength following a period of rest
• Present with ptosis, fatiguability, speech difficulty,
respiratory difficulty
• Treated with cholinesterase inhibitors

14. Anterior cell diseases
• Relatively rare
• Affect any age
• Muscle wasting
• Example: Poliomyelitis
• Adults: MND (motor neuron disease), also called ALS
(amyotrophic lateral sclerosis)
Speech difficulty (dysarthria)
Typical features in EMG test
• Infants: SMA (spinal muscular atrophy)
Breathing difficulty

15. MND dysarthria video clip

16. Plexus, spinal root or spinal cord disorders
• Plexopathies: brachial plexus, lumbosacral plexus
 Erb’s palsy
• Radiculopathies: cervical, thoracic, lumbar, sacral roots
• Myelopathies: cervical, thoracic
• Cauda equina lesions

17. Brainstem disorders
• Sensory motor dysfunction and other features associated with brainstem
• Cranial nerve nuclei could be affected
• Tumors or trauma

21. Motor homunculus
First discovered
by
Penfield

22. Brodmann areas Primary motor cortex
Area 4
Primary somatosensory
Cortex, Area 3b, 1
Primary visual cortex
Supplementary motor area
Premotor cortex
Broca’s area area 44
Secondary sensory area

23. Motor cortex
• different areas of the body are
represented in different cortical areas in
the motor cortex
• Motor homunculus
– somatotopic representation
– not proportionate to structures but
proportionate to function
– distorted map
– upside down map

24. Motor cortical areas
• primary motor cortex (MI)
– precentral gyrus
• secondary motor cortex (MII)
– premotor cortex
– supplementary motor area (SMA)

25. Stroke
• Also called CVA (cerebrovascular accident) or brain attack
• 2nd most common cause of death worldwide (WHO)
• 4th most common cause of death in Sri Lanka
• Commonly hemiplegia occurs

27. Types of strokes
• Ischaemic strokes
(acute ischemic stroke is caused by thrombotic or embolic occlusion of
a cerebral artery and is more common than hemorrhagic stroke)
Large vessel strokes
Lacunar strokes
• Haemorrhagic strokes
(In hemorrhagic stroke, bleeding occurs directly into the brain
parenchyma due to a leakage from small intracerebral arteries
damaged by chronic hypertension)
Intracerebral haemorrhage (ICH)
Subarachnoid haemorrhage (SAH)

28. CT images
Ischaemic strokes Haemorrhagic strokes

29. Lacunar Stroke
• Lacunar infarcts or small subcortical infarcts result
from occlusion of a single penetrating artery and
account for one quarter of cerebral infarctions

30. Cerebral blood vessels
• Anterior and middle cerebral arteries carry the anterior circulation and arise
from the supraclinoid internal carotid arteries
• Anterior cerebral artery (ACA) supplies the medial portion of the frontal and
parietal lobes and anterior portions of basal ganglia and anterior internal
capsule
• Middle cerebral artery (MCA) supplies the lateral portions of the frontal and
parietal lobes, as well as the anterior and lateral portions of the temporal
lobes, and gives rise to perforating branches to the globus pallidus,
putamen, and internal capsule
• MCA is the dominant source of vascular supply to the hemispheres
• Posterior cerebral arteries (PCA) arise from the basilar artery and carry the
posterior circulation
• PCA gives rise to perforating branches that supply the thalami and
brainstem and the cortical branches to the posterior and medial temporal
lobes and occipital lobes

31. Cerebellar arteries
• Inferiorly by the posterior inferior cerebellar artery
(PICA), arising from the vertebral artery
• Superiorly by the superior cerebellar artery
• Anterolaterally by the anterior inferior cerebellar artery
(AICA), from the basilar artery

32. Lacunar infarct
• Pure motor stroke/hemiparesis
 This is the most common (33-50%) lacunar syndrome usually occurs with infarction of the posterior limb of the internal
capsule, which carries the descending corticospinal and corticobulbar tracts, or the basis pontis. It is marked by
hemiparesis or hemiplegia that typically affects the face, arm, or leg of one side. Dysarthria, dysphagia, and transient
sensory symptoms may also be present.
• Ataxic hemiparesis
 This is the second most frequent lacunar syndrome and usually occurs with infarction of the posterior limb of the internal
capsule, basis pontis, and corona radiata. It displays a combination of cerebellar and motor symptoms, including
weakness and clumsiness, on the ipsilateral side of the body. It usually affects the leg more than it does the arm; hence,
it is known also as homolateral ataxia and crural paresis. The onset of symptoms is often over hours or days.
• Dysarthria/clumsy hand
 This is sometimes considered a variant of ataxic hemiparesis (above), but usually still is classified as a separate lacunar
syndrome. The lesion is in the pons and the main symptoms are dysarthria and clumsiness (i.e. weakness) of the hand,
which often are most prominent when the patient is writing.
• Pure sensory stroke
 Marked by persistent or transient numbness, tingling, pain, burning, or another unpleasant sensation on one side of the
body, this infarct is usually in the contralateral thalamus.
• Mixed sensorimotor stroke
 This lacunar syndrome involves hemiparesis or hemiplegia with ipsilateral sensory impairment, with infarct typically in the

33. Watershed
• A watershed stroke or watershed infarct is defined as
an ischemia, or blood flow blockage, that is localized
to the border zones between the territories of two
major arteries in the brain
• Watershed locations are those border-zone regions in
the brain supplied by the major cerebral arteries where
blood supply is decreased

34. Basal Ganglia disorders
• Parkinsonism
• Athetosis
• Chorea
• Hemiballismus
Basal ganglia disorders are also called extrapyramidal disorders

35. Basal ganglia
• Caudate nucleus
• Putamen
• Globus pallidus
–(internal and external)
• Subthalamic nuclei
• Substantia nigra
International Basal Ganglia Society

36. (Ref. Guyton)

37. thalamus
putamen
globus pallidus
caudate

39. Basal ganglia
• caudate nucleus
• putamen
• globus pallidus
• subthalamic nuclei
• substantia nigra
corpus striatum
lentiform
nucleus

40. Parkinsonism
• due to destruction of dopamine secreting pathways from
substantia nigra to caudate and putamen.
 also called “paralysis agitans” or “shaking palsy”
 first described by Dr. James Parkinson in 1817.
• In the west, it affects 1% of individuals after 60 yrs
Classical Clinical features:
• Tremor, resting
• Rigidity of all the muscles
• Akinesia (bradykinesia): very slow movements
• Postural instability

43. Chorea
• Lesions in the caudate
nucleus
• jerky movements of the
hand, face and other parts
• patient is unable to control
them
• may get worse with anxiety
• disappears in sleep

44. Athetosis
• Lesions in putamen
• spontaneous slow
writhing movements
(twisting movements)
of fingers, hands,
toes, feet.

45. Hemiballismus
• Lesions in subthalamus
• violent, flailing
movements of arm & leg
on one side of the body

46. Features of cerebellar disorders
• ataxia
incoordination of movements
ataxic gait
broad based gait
leaning towards side of the lesion
• dysmetria
cannot plan movements
• past pointing & overshoot
• decomposition of movements
• intentional tremor

47. Features of cerebellar disorders
• dysdiadochokinesis
unable to perform rapidly alternating movements
• dysarthria
slurring of speech
• nystagmus
oscillatory movements of the eye

48. Features of cerebellar disorders
• hypotonia
reduction in tone
due to excitatory influence on gamma motor neurons by cerebellum
(through vestibulospinal tracts)
• decreased reflexes
• head tremor
• head tilt
• Rebound
Increased range of movement with lack of normal recoil to
original position

49. Memory and cognitive function
disorders
• Amnesia
 Retrograde amnesia
unable to recall events that occurred before the development of the amnesia
for example due to head injury
 Antegrade amnesia
difficulty in the learning and retention of information encountered after brain
damage, previous memories unaffected
Could occur in head injury, hippocampal lesions, alcoholism,
 A combination of both
• Dementia
 Alzheimer’s disease
Loss of Ach pathways
 Alcoholism
Degeneration of nerve pathways
 Senile dementia
Old age

51. limbic system
• nuclei
– amygdala
– septal nuclei
– mammillary body
– hypothalamus
• cortical areas
– hippocampal gyrus
– cingulate gyrus
– dentate gyrus
– entorhinal, amygdaloid cortex
• paralimbic structures
• orbital gyrus, insula, nucelus accumbens, thalamic
nuclei, superior temporal gyrus,
• fibre tracts: fornix, medial forebrain bundle

52. limbic cortex
• consist of 3 layered cortex (in contrast to 6
layered cortex of the neocortex)

53. Dementia
• Loss of memory
Alzheimer’s dementia
degeneration of brain areas (hippocampus)
decreased acetylcholine
Alcoholism
limbic system (hippocampus) is affected
In old age
senile dementia

54. Alzheimer’s disease
video

55. Alzheimer’s disease
• A progressive, degenerative and fatal brain disease
• in which cell to cell connections in the brain are lost
• as a result, the death of brain cells occur
• Rapid cognitive impairment

57. Other conditions
• Internuclear ophthalmoplegia
Eye movement disorder
Affected eye weak adduction, other eye nystagmus
Medial longitudinal fasciculus (MLF) which connects
abducens and occulomotor pathways affected
Horner’s syndrome
results from an interruption of the sympathetic nerve supply
to the eye and is characterized by the classic triad of miosis
(ie, constricted pupil), partial ptosis, and loss of hemifacial
sweating (ie, anhidrosis).

58. Klippel–Feil syndrome
• This is a rare disease, initially reported in 1912 by
Maurice Klippel and André Feil from France
characterized by the congenital fusion of any 2 of the
7 cervical vertebrae