1. Clinical Neuroanatomy
How Structures Do What They Do & Their Clinical Implications
Karen L. Kepler DO Ph.D
Director Neurocognitive Rehabilitation
Kessler Institute for Rehabilitation

2. Organization of the Nervous System
Central (CNS)
Brain
Spinal Cord
Peripheral (PNS)
Spinal Nerves
Small peripheral nerves
Autonomic system
Parasympathetic
Sympathetic

3. Organization of the Nervous System
Left Brain
Works the right side of the body
“accountant”
Executive function
Speech
Judgement
Inhibitions
Dominant in most people (even if you are left handed)
Right Brain
Works the left side of the body
“artist”
Spatial perception
Creativity

4. Organization of the Nervous System

5. Organization of the Nervous System
Supratentorial
All the high level structures
If injured, you lose high level functions first
Infratentorial
Primitive part of the brain
Includes cerebellum, brainstem, 4th ventricle
Pressure here is super dangerous due to tight enclosure and risk of hemodynamic instability

6. Organization of the Nervous System

7. Organization of the Nervous System
Gray Matter
Higher level functions
Highest level is on the cortex (surface)
Easy to injure due to:
Relatively superficial location
Requires more blood flow than does white matter
White Matter
Survival functions
Deep in the brain

8. Growing your Nervous System
Embryological development—begins in 1st trimester
Development of the Neural Plate--evolves into neural tube closure of neural tube begins evolution to central nervous system

9. Growing your Nervous System

10. Pathology Associated with Disrupted Embryologic Development
Meninges and cord protrusion through vertebrae— myelomeningocele

11. Pathology Associated with Disrupted Embryologic Development
Brain protrusion through skull defect —encephalocele

12. Pathology Associated with Disrupted Embryologic Development
Failure of Neural tube closure— anencephaly

13. Neural Cells Types of Cells sensory association motor
Neuron—functional unit of the CNS
Types of Neurons
sensory
association
motor
Groups of cell bodies—called ganglia in peripheral system and nuclei in central system

14. Cell Body

16. Supporting Cells Neural Cells Astrocyte—nutrition/use transmitters
Oligodendrocytes– produce myelin
Microglia—phagocytosis

17. Pathology Associated with Nerve Cells/ Neurotransmitters
Alzheimer’s & Myasthenia Gravis— acetylcholine
Schizophrenia & mood disorders—serotonin, dopamine
Parkinson’s disease-- defect in dopamine secreting neurons (substantia nigra)
Arousal associated with histamine
Seizure disorders & pain syndrome—GABA
Pain disorders—Substance

18. Protection for CNS Skull Temporal bone is thinnest
Fontanels close in child hood

19. Protection for CNS Vertebrae Surround spinal cord 7 Cervical
12 Thoracic
5 Lumbar
5 Sacral (fused; no or rudimentary discs between them)
Coccyx (1)

20. Areas of Weakness

21. Protective Structures
Meninges—protective membranes covering brain & spina cord
dura mater—Hard mother; space between dura and skull is the epidural space and is the location of several arteries
arachnoid mater—Spider mother; POTENTIAL space between dura and arachnoid is the subdural space and is the location of several veins
pia mater—Delicate mother; space between the arachnoid and pia is the sub-arachnoid space and contains cerebral spinal fluid

22. Protective Structures
Meninges

23. Protective Structures
Cerebrospinal Fluid (CSF)
Make 500 cc per day, but only have 150 cc circulating at any given time
Circulates all around brain & spinal cord
Old CSF gets absorbed by arachnoid villi and dumped into venous system
Contains glucose (should not contain blood, high levels of protein)

24. Protective Structures

25. Pathology Related to Protective Structures
Hematomas
Epidural: arterial usually, between skull & dura mater
Often need surgical evacuation

26. Pathology Related to Protective Structures
Subarachnoid Hemorrhage
Arterial bleed, from aneurysm rupture or trauma
CSF space will contain bloody CSF
Sudden onset, worst headache of your life

27. Pathology Related to Protective Structures
Meningitis
Viral, bacterial or fungal
Infection & inflammation of meninges

28. Brain Structures Cerebrum Cerebellum Brainstem Pituitary Gland
Lobes: frontal, temporal, parietal, occipital
Basal ganglia
Corpus callosum
Limbic system
Thalamus
Hypothalamus
Cerebellum
Brainstem
Midbrain
Pons
Medulla
Pituitary Gland

29. Brain Structures LOBES Frontal Executive function Judgement
High level cognition
Making speech (Broca’s area)
Motor strip

30. Brain Structures
Sensory Homunculus
Motor Homunculus

31. Brain Structures LOBES Temporal
Interpretation of what is heard/receptive speech (Wernicke’s area)
Closely associated with emotions
Brain Structures

32. Brain Structures LOBES Parietal Occipital Sensory Strip Perception
Spatial relations
Occipital
Visual interpretation

33. Parietal
Frontal
Temporal
Occipital

34. Pathology Related to Cerebral Lobes
Tumors
May be benign or varying degrees of cancerous

35. Pathology Related to the Cerebrum
Traumatic Brain injury
Concussion—diffuse shearing/stretching of neurons heralded by a short LOC; neg MRI/CT
Diffuse Axonal Injury —diffuse shearing/stretching of fibers; usually worsens from time of initial injury due to diffuse cerebral edema
Missile injuries—gunshot wounds; damage done by tearing, swelling, infection
Hematomas/Contusions --can be anywhere in the brain but most common in frontal & temporal areas

36. Pathology Related To Cerebrum
Contusions
Hematomas

37. Pathology Related To Cerebrum
Diffuse Axonal Injury
Missile Injury

38. Brain Structures Limbic system Responsible for primitive emotions
Located near temporal lobe

39. Brain Structures Basal Ganglia 2 nuclei of gray matter deep in brain
Responsible for coordination of movement
Dopamine works here

40. Pathology Related to Basal Ganglia
Parkinson’s Disease
TRAP: Tremors, rigidity, akinesia, postural disturbance
Not enough dopamine produced by substantia nigra in midbrain and being sent to basal ganglia, where it works

42. Pathology Related to Basal Ganglia
Supranuclear Palsy
Damage to substantia nigra, causing lack of dopamine production
Results in inability to move eyes, swallow + other symptoms similar to Parkinson’s Disease

43. Brain Structures Thalamus
Major relay station for incoming messages from the periphery
“postoffice”

44. Brain Structures Hypothalamus
Sits below thalamus and above pituitary gland
Internal regulator
Regulates satiation/appetite, visible responses to emotions, temperature

45. Brain Structures Pituitary Gland Master gland
Dangles from a stalk attached to the hypothalamus, at optic chiasm
Secretes hormones

46. Pathology related to Pituitary Gland
DI vs SIADH
Too little vs too much ADH
Pituitary tumor
Hormonal changes
Visual disturbances

47. Anopsias (visual tract problems)

48. Brain Structures Cerebellum 2 lobes at base of brain Nestles brainstem
Responsible for coordination & balance
Left side works left body, right side works right body
Problems: ataxia, incoord- ination, tremors

49. Brain Structures Brainstem 3 parts: Midbrain, Pons, Medulla oblongata
Responsible for vital signs
Site of exit for 10 of the 12 pairs of cranial nerves
About the size of your thumb
High Dollar Real Estate

51. Brain Structures Reticular Activating System
determines the state of consciousness and arousal
Comprised of: medulla, reticular formation, substantia nigra, cortex, brainstem, limbic System
Problems with RAS implicated in:
Parkinson’s, Alzheimer’s, PSP, PTSD, schizophrenia, narcolepsy
Wakefulness determined by brainstem and RAS
Attention determined by limbic system and cortex

53. Cranial Nerves 12 pairs (10 of which come off the brainstem)
CN II: vision
CN III: pupillary function, keeping eye open, most of the eye movements
CN III, IV, VI: eye movements
CN IX, X, XII: cough, gag swallow
What we are testing with brain death tests

54. Brain Vasculature Unique system as compared to the rest of the body:
Veins don’t retrace the path of the arteries
Arteries are very thin walled
Veins have even thinner walls

55. Arteries of Brain
Internal Carotids feed the anterior portion of the brain
Vertebral arteries join to become the basilar artery and feed the posterior portion of the brain

56. Arteries of Brain Circle of Willis To allow for collateral flow
Largest artery in circle & most commonly “stroked” is Middle Cerebral Artery (MCA)

57. Arterial Vascular Territories

58. Veins of the Brain
Small veins deep in brain get larger when they reach the surface & then are called “sinuses”
Do not have valves so have to accept blood flow passively (making them prone to bleeding)
Blood drained from brain by internal jugulars

59. Veins of the Brain

60. Pathology of Vasculature System in Brain
Stroke/CVA (cerebrovascular accident)
Lack of blood flow to a region of the brain fed by a specific vascular territory
Thrombotic (most common): plaque/platelets in arteries occlude blood flow
Embolic: fat, air, clot from outside the brain enter the brain vasculature and occlude blood flow
Most common artery occluded is middle cerebral artery (MCA) because it is the most direct path from the carotids

61. Pathology of Vasculature System in Brain

62. Pathology of Vasculature System in Brain
Cerebral Aneurysms
Weakened arterial wall, causing a pouch on the artery, with risk of rupture
Often asymptomatic
If rupture, cause a subarachnoid hemorrhage
Most common artery involved is the anterior communicating artery (AcommA)

63. Pathology of Vasculature System in Brain
Arterial Venous Malformations (AVM)
Congenital vascular lesion
Arteries dump directly into veins without an intervening capillary network
Can bleed, usually into brain tissue
Can also be on spinal cord

64. Spinal Cord
Starts at bottom of brainstem (medulla) and ends in the conus medullaris (L1 or L2 level in most people)
Communication pathway between the brain and the peripheral nerves
Made of Gray Matter & White Matter
Anterior cord: motor (efferent/descending)
Lateral cord: pain, temperature and sensation (afferent/ascending)
Posterior cord: position & vibratory sense (afferent/ascending)

67. Spinal Cord
Sensory Tracts carry signals from the periphery to the brain, crossing at or in the medulla
ASCENDING/AFFERENT, found in the posterior and lateral aspects of the spinal cord
Spinocerebellar
Spinothalamic
Fasciculus Cunneatus
Fasciculus Gracilis

69. Spinal Cord
Motor Tracts carry signals from the brain to the periphery, crossing at or in the medulla
DESCENDING/MOTOR, found in the lateral aspects of the spinal cord
Corticospinal
Rubrospinal
Vestibulospinal
Reticulospinal
Tectospinal

70. Upper Motor Neurons
Connect the brain with the anterior horn of the spinal cord (so, involves the brain or spinal cord)
Injury to UMNs result in:
spasticity
hyper-reflexia
paresthesias **myelopathy

71. Lower Motor Neurons
Connect the peripheral nerves with the spinal cord (so involves periphery)
Injury to LMNs result in:
flaccidity
hypo-reflexia
paresthesias **radiculopathy

72. Pathology of Spinal Cord
Injury from contusions, infarction, laceration, edema, tumors, infection, disc herniation
ASIA classifications of SCI:
Incomplete: some preservation of movement or sensation below the level of injury (more common)
Complete: total absence of movement or sensation below the level of injury

73. Pathology of Spinal Cord
SCI syndromes:
Quadriplegia
Involves cervical spine
Paraplegia
Involves thoracic or uppermost lumbar spine L1 or possibly
L2)

74. Pathology of Spinal Cord
SCI syndromes:
Central Cord:
Loss of motor function in a distally and more to upper than lower extremities

75. Pathology of Spinal Cord
SCI syndromes:
Brown Sequard
Loss of motor function on the ipsilateral side and loss of sensory function on the contralateral side

76. Pathology of Spinal Cord
SCI syndromes:
Horner’s Syndrome
Miosis (small pupil), ptosis (droopy eyelid) & anhydrosis (loss of sweating) ipsilateral to a cervical lesion
Tumor or other lesion to sympathetic chain of the cervical or thoracic nerves

77. Pathology of Spinal Cord
Cervical fracture
Cervical disc herniation
Epidural Abscess
Syringomyelia

78. Pathology of Spinal Cord
Spinal Shock
Occurs after SCI (more often if complete)
Loss of reflexes (along with movement & sensation) below level of lesion, lasting 1-3 days
Followed by gradual return of reflexes (starts with return of anal wink)
This is NOT the same thing as neurogenic shock (which can occur simultaneously)
Autonomic dysreflexia cannot occur until after spinal shock resolves (within about 4 weeks)

79. Pathology of Spinal Cord

80. Pathology of Spinal Cord

81. Pathology of Spinal Cord
Amyotrophic Lateral Sclerosis (ALS)/Lou Gehrig’s Disease
Destruction of anterior horn cells of spinal cord
Progressive weakness, starting distally and moving proximally

82. Pathology of Spinal Cord
Multiple Sclerosis
Degenerative disease of CNS
Myelin sheath stripped/ damaged, leaving plaques that come & go in brain
Different forms: relapsing/ remitting, progressive
Weakness, paresthesias, optic neuritis, bowel/bladder dysfunction

83. Spinal Nerves 31 pairs Upper nerves exit horizontally
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
Upper nerves exit horizontally
Lower nerves exit vertically, hence, the cauda equina (horse’s tail at the conus medullaris)

86. Dermatomes

87. Spinal Nerves Autonomic Nervous System Sympathetic Parasympathetic
Comes off thoracic & lumbar areas
“Fight or Flight:” everything bigger & faster
Parasympathetic
Comes off cervical & sacral areas
“Pig/Rest & Digest:” everything smaller & slower

89. Spinal Nerves Important levels to remember:
C3,4,5 Keep the Diaphragm Alive
S2, 3, 4 Urination
S2, 3, 4 Defecation

90. Pathology of Autonomic Nervous System
Severe HTN, bradycardia, anxiety, flushed skin above the lesion, stroke

91. Reflex Arc
Occurs between the periphery and the spinal cord (does not involve the brain at all)
Comprised of: afferent neuron, efferent neuron, and effector muscle or gland
Safety/survival mechanism

93. B. This is the phrenic nerve

94. Which of the following nerves control (s) the diaphragm?
Spinal nerves C5, 6, 7
Spinal nerves C3, 4, 5
Spinal nerves T1, 2, 3
Cranial nerve XI
B. This is the phrenic nerve

95. Orthostatic hypotension, temperature regulation problems, and autonomic dysreflexia are all associated with which level of spinal cord injury (SCI)?
At or below T10
At or above T8
C) At or above T6
D) At or below L1 C.

96. Which finding is consistent with a lower motor neuron lesion?
Muscle strength scored 5
Patellar reflex ++
Bulbocavernosus reflex present
Deep tendon reflex absent
d. LMN are part of the reflex arc. If they are injured the reflex cannot occur