Neuroanatomy Quiz: White Matter Functions

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Questions and Answers

Which part of the white matter is located at the front of the spinal cord?

Lateral white column

Anterior white commissure

Posterior white column

Anterior (Ventral) white column (correct)

What is the function of neuroglial cells in relation to nerve fibers?

They create myelin sheaths.

They carry nutrients to neurons.

They provide structural support and protection. (correct)

They transmit electrical impulses.

Which of the following is NOT a division of white matter?

Lateral white column

Anterior (Ventral) white column

Cerebral white column (correct)

Posterior (Dorsal) white column

What is located at the center connecting the anterior and posterior white columns?

Anterior white commissure Signup and view all the answers

Which white column is primarily responsible for sensory information?

Posterior (Dorsal) white column Signup and view all the answers

What is the significance of the year 2023 in the context provided?

It represents the year in which the document was prepared. Signup and view all the answers

Which entity is associated with the document titled 'Ascending Tracts'?

University of Najran Signup and view all the answers

How is the academic year represented in the content?

In a format typical for university documents. Signup and view all the answers

What is indicated by the phrase 'العمادة/الكلية/اسم الوكالة' in the context?

It describes the administrative structure of the university. Signup and view all the answers

What is the role of the nonprofit organization mentioned in the document?

It supports educational initiatives and reforms. Signup and view all the answers

What is the role of the spinoreticular tract in relation to the reticular formation?

It determines consciousness levels. Signup and view all the answers

Which structure receives afferent fibers from the spinoreticular tract?

Reticular formation Signup and view all the answers

How does the spinoreticular tract influence consciousness?

By affecting the reticular formation. Signup and view all the answers

Which of the following best describes the relationship between consciousness and the reticular formation?

The reticular formation is vital for determining consciousness levels. Signup and view all the answers

Which function is primarily associated with the reticular formation?

Determining consciousness levels. Signup and view all the answers

What is the path of first-order neuron axons when they enter the spinal cord?

They proceed to the tip of the posterior gray column and then divide. Signup and view all the answers

Which structures do first-order neuron fibers typically terminate in when synapsing?

Cells in the substantia gelatinosa within the posterior gray horn. Signup and view all the answers

What is the name of the tract that first-order neuron fibers travel in after entering the spinal cord?

Posterolateral tract of Lissauer. Signup and view all the answers

How far can first-order neuron fibers travel within the spinal cord before synapsing?

Between 1 to 2 segments of the spinal cord. Signup and view all the answers

Which part of the spinal cord does the axon of the first-order neuron primarily interact with?

The posterior gray column. Signup and view all the answers

Which author is associated with the clinical neuroanatomy text cited?

Richard S. Snell Signup and view all the answers

What is the primary focus of the text by John T. Hansen?

Clinical anatomy with online access Signup and view all the answers

In which year was the 3rd edition of Netter's Clinical Anatomy released?

2014 Signup and view all the answers

Which publisher released Richard S. Snell's clinical neuroanatomy edition?

Lippincott Williams & Wilkins Signup and view all the answers

What is the likely purpose of accessing John T. Hansen's text online?

To access additional online resources Signup and view all the answers

What is the primary function of the axons that ascend in the lateral white column as the spinoreticular tract?

To connect with reticular formation neurons Signup and view all the answers

Where do the majority of the spinoreticular tract fibers make synapses?

With reticular formation neurons Signup and view all the answers

Which brain regions do the spinoreticular tract axons synapse with?

Midbrain, medulla oblongata, and pons Signup and view all the answers

What characteristic distinguishes the majority of fibers in the spinoreticular tract?

They are mainly uncrossed Signup and view all the answers

Which aspect of the spinoreticular tract's connection to the central nervous system is accurate?

The axons ascend without crossing in most cases Signup and view all the answers

Study Notes

Ascending Tracts (Sensory Pathways)

Information is divided into two main groups: Exteroceptive and proprioceptive.
Exteroceptive information originates from outside the body (pain, temperature, touch).
Proprioceptive information originates from inside the body (muscles, joints).

Three-Neuron Pathways

Primary sensory neurons (1st order): from external receptors, travel through dorsal roots of spinal cord.
Secondary sensory neurons (2nd order/interneurons): give rise to an axon that decussates and ascends to a higher level of the central nervous system.
Tertiary sensory neurons (3rd order/thalamic neurons): originate from the thalamus, project to primary sensory cortex, travel through the internal capsule.

A) Anterolateral Spinothalamic Tract

Carries information about pain, temperature, crude touch, and pressure.
1st order neuron enters spinal cord via dorsal root, synapses on 2nd order neuron, decussates, ascends to brain, synapses on 3rd order neuron (in thalamus), terminates in somatosensory cortex.

Lateral Spinothalamic Tract

Carries impulses concerned with pain and temperature (thermal sensations).
Axons of 1st order neurons enter the spinal cord from the posterior root ganglion, proceed to the posterior gray column, divide into ascending and descending branches, and travel for a distance of one or two segments as the posterolateral tract of Lissauer.
Fibers of the first-order neuron terminate by synapsing with cells in the posterior gray horn, including cells in the substantia gelatinosa.
Axons of 2nd order neurons decussate obliquely within one segment of their origin, passing through the ventral white commissure and terminate on 3rd order neurons in the ventral posterolateral nucleus of the thalamus.
Thalamic neurons project to the somatosensory cortex through the posterior limb of the internal capsule.

B) Posterior (Dorsal) Column (Fasciculus Gracilis and Fasciculus Cuneatus) and Medial Lemniscus

Contains two tracts: Fasciculus gracilis (FG) and Fasciculus cuneatus (FC).
Carries information of conscious proprioception (muscle joint sense), discriminative touch, and vibratory sense.

C) Spinocerebellar Tract

The spinocerebellar system consists of a sequence of two neurons.
Two tracts: posterior (ipsilateral) and anterior (contralateral).
Carries information of proprioception derived from muscle spindles, Golgi tendon organs, and tactile receptors (Merkel's disks, Meissner's corpuscles, Ruffini endings, Pacinian corpuscle, and Krause end bulbs).
Terminates in the cerebellum.
Controls posture and coordination of movements.

Posterior Spinocerebellar Tract

Present only above level L3.
Cell bodies of 2nd order neuron lie in Clark's column (dorsal or posterior thoracic nucleus).
Axons of 2nd order neurons terminate ipsilaterally in the cerebellar cortex by entering through the inferior cerebellar peduncle.

Anterior Spinocerebellar Tract

Cell bodies of 2nd order neuron lie in the base of the dorsal horn of the lumbosacral segments.
Axons of 2nd order neurons cross to the opposite side, ascend to the midbrain, and enter the superior cerebellar peduncle.
The fibers cross the midline again within the cerebellum before terminating in the cerebellar cortex.
Both spinocerebellar tracts convey sensory information to the same side of the cerebellum.

D) Spinotectal Tract

From the posterior root ganglion, axons enter the spinal cord and proceed to the grey matter to form synapses with unidentified second order neurons.
The second-order neurons' axons climb as the spinotectal tract in the anterolateral column after crossing the median plane.
They terminate by forming synapses with neurons in the superior colliculus of the midbrain.
This pathway provides afferent information for spinovisual reflexes and brings about movements of the eyes and head towards the source of the stimulation.

E) Spinoreticular Tract

From the posterior root ganglion, axons enter the spinal cord and proceed to the grey matter to form synapses with unknown second-order neurons.
These second-order neurons' axons ascend the lateral white column as the spinoreticular tract.
The majority of the fibers are uncrossed and come to an end by making synapses with reticular formation neurons in the midbrain, medulla oblongata, and pons.
The reticular formation receives afferent fibers from the spinoreticular tract, which is crucial in determining consciousness levels.

F) Spino-olivary Tract

The axons enter the spinal cord from the posterior root ganglion and terminate on unknown second-order neurons in the posterior gray column.
The second-order neurons ascend after crossing the midline at the junction of the anterior and lateral white columns as the spino-olivary tract.
In the inferior olivary nuclei of the medulla oblongata, axons terminate by forming synapses with third-order neurons.
The axons of the third-order neurons enter the cerebellum via the inferior cerebellar peduncle after crossing the midline.
The spino-olivary tract conveys information to the cerebellum from cutaneous and proprioceptive organs.

References

Clinical neuroanatomy / Richard S. Snell. — 7th ed. Lippincott Williams & Wilkins-Philadelphia
Netter's Clinical Anatomy
Last's anatomy Regional and applied
Gray's Anatomy

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Description

Test your knowledge on the functions and structures of white matter in the spinal cord. This quiz covers topics including neuroglial cells, sensory information pathways, and the relationship between consciousness and neuroanatomical structures. Challenge yourself with questions related to ascending tracts and the roles of specific neural pathways.