Somesthetic Sensation Flashcards
What is a dermatome?
A. The area of skin supplied by axons from a single ventral horn.
B. A surgical instrument used to section bodies.
C. The area of skin innervated by a dorsal root ganglion.
D. A region of sensory-motor cortex associated with one area of skin.
E. Any skin area densely innervated by C-fibers.
The area of skin innervated by a dorsal root ganglion.
In the thoracic region there is overlap between the nerves that innervate neighboring dermatomes. Thus, a lesion of one dorsal root produces hypesthesia rather than anesthesia. To get complete cutaneous anesthesia in the thoracic area, at least three adjoining spinal nerves or their dorsal roots must be affected. There is much less overlap in the extremities where borders between dermatomes are sharper. Shingles, is a herpes infection of dorsal root ganglia with skin lesions. The eruption outlines the dermatome
What is the significance of the dermatome?
A. It enables the clinician to differentially diagnose muscle disease.
B. It enables the clinician to locate lesions affecting the spinal cord or spinal nerves.
C. It allows a clear distinction between a distal and proximal lesion along a peripheral nerve.
D. All of the above.
E. None of the above.
It enables the clinician to locate lesions affecting the spinal cord or spinal nerves.
Regarding this poorly myelinated tract:
A. It consists of first order sensory axons with ascending and descending branches which run longitudinally for 1 to 3 segments.
B. It is made up of second order sensory axons which ascend ipsilaterally to the gracile nucleus in the medulla.
C. It contains axons responsible for the monosynaptic reflex.
It consists of first order sensory axons with ascending and descending branches which run longitudinally for 1 to 3 segments.
What forms this commissure of the spinal cord?
A. Second order spinothalamic tract (anterolateral system) axons.
B. Local interneurons.
C. Both of the above.
D. Neither of the above.
Both of the above
Should the region of the central canal expand, as it did in this case of syringomyelia, what will happen ?
A. The local monosynaptic Ia motoneuron reflexes will be impaired or missing.
B. The pressure may impair or destroy the anterior white commissure and hence cause a bilateral loss of pain and thermal sensation in the corresponding dermatomes.
C. The pressure will destroy the dorsal columns resulting in a loss of fine touch and vibratory sense.
D. There will be no clinical problem.
The pressure may impair or destroy the anterior white commissure and hence cause a bilateral loss of pain and thermal sensation in the corresponding dermatomes.
In the medulla, where is the anterolateral system located with respect to the nucleus ambiguus?
A. It is dorsal to the nucleus ambiguus.
B. It is medial to the nucleus ambiguus.
C. It is ventral to the nucleus ambiguus.
D. It is lateral to the nucleus ambiguus.
It is lateral to the nucleus ambiguus
What is the functional significance of the dorsolateral fasciculus or Tract of Lissauer?
A. It is a tract associated with the sympathetic chain.
B. It contains axons involved in spinal reflexes and intersegmental integration.
C. Both.
D. Neither.
It contains axons involved in spinal reflexes and intersegmental integration.
If this tract is surgically interrupted at the level of the inferior colliculus, what dermatomes would be affected ?
A. C1 through T5 of the ipsilateral side.
B. All dermatomes on the contralateral side.
C. All dermatomes on the ipsilateral side.
D. T5 through S5 of the contralateral side.
E. T5 through S5 of the ipsilateral side.
All dermatomes on the contralateral side.
The cuneate fasciculus is located at this level of the spinal cord.
A. True.
B. False.
False.
The dorsal columns are organized:
A. Somatotopically with the medial fibers representing the cervical and the lateral fibers representing sacral dermatomes.
B. With medial fibers representing sacral regions and lateral fibers cervical regions.
C. There is NO somatotopic organization of the dorsal columns.
With medial fibers representing sacral regions and lateral fibers cervical regions.
How are the dermatomes represented in the anterolateral system?
A. They are represented somatotopically with the sacral axons more superficial, and the cervical segments more medial.
B. There is no somatotopic organization of the anterolateral system.
C. They are represented somatotopically such that as one progresses from the pial surface inward one encounters cervical, thoracic, lumbar and then sacral axons.
They are represented somatotopically with the sacral axons more superficial, and the cervical segments more medial.
Where are the cells of origin for the circled axons ?
A. In the dorsal horn of the spinal cord.
B. In the dorsal root ganglia.
C. In the dorsal column nuclei.
D. In the intermediolateral cell column.
In the dorsal root ganglia.
A patient complains of numbness of the fingers which progresses to loss of temperature sensation bilatterally. This condition results from:
A. Damage to the dorsal columns.
B. Bilateral compression of the anterolateral system.
C. Damage to the spinothalamic tract.
D. Interruption of the anterior white commisure.
Interruption of the anterior white commisure.
Occlusion of this artery is often associated with:
A. Aphasia.
B. Slurred speech.
C. Hoarsness.
D. Stuttering.
Slurred speech
Axons in this tract convey information from dermatones:
A. On the ipsilateral side of the body.
B. On the contralateral side of the body.
C. From both sides of the body.
On the ipsilateral side of the body
At his level the cuneate fasciculus is:
A. Present in the dorsal columns.
B. Absent in the dorsal columns.
Absent in the dorsal columns.
Sensory dissociation is the loss of pain and temperature with sparing of vibration, joint position, and fine touch. By knowing the location of the two pathways that carry the information, and knowing where the second order axons cross, you conclude that this will most likely occur at which level:
A. Thalamus.
B. Midbrain.
C. Pons.
D. Medulla.
Medulla
