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Specific Lesions
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Carpenter, Human Neuroanatomy, p271
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Specific Lesions
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Carpenter, Human Neuroanatomy, p271
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Specific Lesions
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Carpenter, Human Neuroanatomy, p271
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Specific Lesions
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Specific Spinal Cord Lesions
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Carpenter, Human Neuroanatomy, p271
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Specific Spinal Cord Lesions
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Specific Brain Stem Lesions
These lesions will result in loss of conscious
proprioception (fine discrimination touch,
pressure, vibratory sense) in the right leg and
lower trunk. What is lesioned Gracile
fasciculus. This contains the central processes
of the primary afferents ascending to ultimately
synapse in the nearby Gracile nucleus. The
pathway has not crossed! So the effect is
ipsilateral. This region carries information
from the lower part of the body. This is the
dorsal column system so it mediates conscious
proprioception.
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Specific Brain Stem Lesions
Result is loss of conscious proprioception in the
left leg and lower body. What is lesioned
Gracile nucleus. These are the cell bodies of
the second order neurons. The pathway has not
yet crossed so the effect is ipsilateral. It is
lower body because it is Gracile nucleus (not
Cuneate which carries upper body info). It is
conscious proprioception because these are
components of the dorsal column system.
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Specific Brain Stem Lesions
The result is a loss in conscious proprioception
in the right arm and upper body. What is
lesioned is the cuneate nucleus. It is
ipsilateral because these are the cell bodies of
the second order neurons and the pathway has not
yet crossed. It is the upper body because it is
the cuneate nucleus (lower body gracile
nucleus). It is conscious proprioception because
this is part of the dorsal column system.
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Specific Brain Stem Lesions
The effect is loss of conscious proprioception on
the right side of the body. What is lesioned
internal arcuate fibers. These are the axons of
the second order neurons just BEFORE they have
crossed the midline. The effect is ipsilateral
because they have not YET crossed. It will
affect both upper and lower parts of the body
because axons from both gracile and cuneate
nuclei are running here. Modality is conscious
proprioception (fine discrimination touch)
because these are part of the dorsal column
system.
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Specific Brain Stem Lesions
Dorsal
Ventral
Result is loss of conscious proprioception (fine
discrimination touch) on the right side of the
body. What is lesioned medial lemniscus. The
effect is contralateral because the axons of this
tract have crossed the midline (as the internal
arcuate fibers). Both upper and lower parts of
body will be affected, because the axons of both
the gracile and cuneate nuclei contribute to this
tract. The gracile neurons send their axons to
the ventral portion of the tract and the cuneate
neurons send their axons to the dorsal portion of
the tract.
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Practice Question 1

• Which statement is true regarding the shaded area
  below?
• Pathway terminates on the left side of the spinal
  cord
• Pathway arises from cells in the dorsal horn on
  the left side of the spinal cord
• Pathway terminates in the left VPL
• Pathway arises from cells in the dorsal root
  ganglion on the right
• Pathway arises from cells in the right motor
  cortex

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Practice Question 2

• Which statement is true regarding the shaded area
  below?
• Cells project to the left VPM
• Pathway arises from cells in the right trigeminal
  ganglion
• Pathway arises from cells in the dorsal horn on
  the left side of the spinal cord
• Cells project to the right VPL
• Cells project to the right VPM

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Practice Question 3

• Which statement is true regarding the shaded area
  below?
• Lesion results in loss of pain and temperature
  from the right side of the face
• Axons end in the left VPM
• Axons arise from the right trigeminal ganglion
• Axons arise from the right ganglion of IX
• Lesion results in a loss of pain and temperature
  from the left side of the face

Area lesioned Spinal Trigeminal Nucleus
Right
Left
Midline
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Clinical Problems
Where is the lesion??
Q1. Loss of muscle joint sense of the left leg.
Right trunk and leg - total analgesia,
thermoanesthesia
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Clinical Problems
What is the clinical problem and where is the
lesion?
Q2. Analgesia and thermoanesthesia on the left
hand, had previously burned the little finger of
left hand but was unaware until smelled the
burning skin. On Exam Reduced pain and
temperature sense involving the 8th cervical and
first thoracic dermatomes of the left hand, but
tactile discrimination normal. Right arm similar
but much less severe.
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Clinical Problems
Q3. 60 yr old man raises his feet unnecessarily
high and brings them to the ground in a stamping
manner, stands with feet wide apart. Finding it
difficult to walk, especially in dark. Asked to
stand with toes and heels together and then close
eyes patient begins to sway. Loss of muscle
joint sense, vibration sense of both legs.