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Questions and Answers
What anatomical structure marks the beginning of the spinal cord?
What anatomical structure marks the beginning of the spinal cord?
Which spinal cord enlargement corresponds with the spinal levels C5 to T1?
Which spinal cord enlargement corresponds with the spinal levels C5 to T1?
What is the total number of pairs of spinal nerves that arise from the spinal cord?
What is the total number of pairs of spinal nerves that arise from the spinal cord?
The conus medullaris is located at the interface of which lumbar vertebrae?
The conus medullaris is located at the interface of which lumbar vertebrae?
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Which part of the spinal cord contains the dorsal horn, ventral horn, and the intermediate zone?
Which part of the spinal cord contains the dorsal horn, ventral horn, and the intermediate zone?
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What defines the anterior gray horns in the spinal cord?
What defines the anterior gray horns in the spinal cord?
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What unique feature does the spinal cord possess compared to other components of the CNS?
What unique feature does the spinal cord possess compared to other components of the CNS?
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Which of the following correctly describes the arrangement of white matter in the spinal cord?
Which of the following correctly describes the arrangement of white matter in the spinal cord?
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What characteristic distinguishes the lumbar level of the spinal cord from the thoracic level?
What characteristic distinguishes the lumbar level of the spinal cord from the thoracic level?
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Which statement accurately describes the sacral level of the spinal cord?
Which statement accurately describes the sacral level of the spinal cord?
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What is the role of the lumbar cistern in the spinal cord?
What is the role of the lumbar cistern in the spinal cord?
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Which fasciculus contains primary sensory axons from spinal cord segments C2-T6?
Which fasciculus contains primary sensory axons from spinal cord segments C2-T6?
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What bounds the fasciculus gracilis laterally?
What bounds the fasciculus gracilis laterally?
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Which structure provides a non-neuronal extension from the conus medullaris?
Which structure provides a non-neuronal extension from the conus medullaris?
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In the context of spinal cord anatomy, what is the relationship of the fasciculus cuneatus to the posterior lateral sulcus?
In the context of spinal cord anatomy, what is the relationship of the fasciculus cuneatus to the posterior lateral sulcus?
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What are the primary components of white matter in the spinal cord?
What are the primary components of white matter in the spinal cord?
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Where is the cauda equina found in relation to the lumbar cistern?
Where is the cauda equina found in relation to the lumbar cistern?
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What distinguishes the dorsal funiculus in the spinal cord?
What distinguishes the dorsal funiculus in the spinal cord?
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What is the anatomical significance of the anterior lateral sulcus?
What is the anatomical significance of the anterior lateral sulcus?
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What is the main function of the posterior intermediate sulcus?
What is the main function of the posterior intermediate sulcus?
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What type of nerve roots does the cauda equina give rise to?
What type of nerve roots does the cauda equina give rise to?
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What anatomical structures are defined as funiculi?
What anatomical structures are defined as funiculi?
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Which structure is responsible for the exit of sensory nerve roots into the spinal cord?
Which structure is responsible for the exit of sensory nerve roots into the spinal cord?
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What are the three regions that motor neurons are somatotopically arranged into within the grey matter of the ventral spinal cord?
What are the three regions that motor neurons are somatotopically arranged into within the grey matter of the ventral spinal cord?
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Which characteristic does not apply to the thoracic level of the spinal cord?
Which characteristic does not apply to the thoracic level of the spinal cord?
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Which section of the spinal cord is characterized by providing motor neurons for the upper limbs?
Which section of the spinal cord is characterized by providing motor neurons for the upper limbs?
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What unique feature is found in the thoracic cord that is not present in the cervical cord?
What unique feature is found in the thoracic cord that is not present in the cervical cord?
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Which of the following accurately describes the shape of the spinal cord at the cervical level?
Which of the following accurately describes the shape of the spinal cord at the cervical level?
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The ventral horn of the spinal cord is primarily associated with which type of neurons?
The ventral horn of the spinal cord is primarily associated with which type of neurons?
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In which spinal cord region is the ratio of white matter to gray matter notably increased?
In which spinal cord region is the ratio of white matter to gray matter notably increased?
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What is the primary function of axially located muscles according to the spinal cord motor mapping?
What is the primary function of axially located muscles according to the spinal cord motor mapping?
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Which spinal segment contains the pre-ganglionic sympathetic neurons in the lateral horn?
Which spinal segment contains the pre-ganglionic sympathetic neurons in the lateral horn?
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What mapping is illustrated by Figure 5a regarding motor neuron distribution?
What mapping is illustrated by Figure 5a regarding motor neuron distribution?
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What is the primary function of the dorsal horn in the spinal cord?
What is the primary function of the dorsal horn in the spinal cord?
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Where are the preganglionic sympathetic motor neurons located?
Where are the preganglionic sympathetic motor neurons located?
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Which structure is characteristic of the lateral horn in the spinal cord?
Which structure is characteristic of the lateral horn in the spinal cord?
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What defines the fasciculus cuneatus in the dorsal funiculus?
What defines the fasciculus cuneatus in the dorsal funiculus?
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What is the composition of gray matter in the spinal cord?
What is the composition of gray matter in the spinal cord?
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Which commissure contains heavily-myelinated axon fibers that cross to the opposite side?
Which commissure contains heavily-myelinated axon fibers that cross to the opposite side?
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What is the role of the ventral (anterior) horn?
What is the role of the ventral (anterior) horn?
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Which part of the spinal cord is associated with the region of the lateral horn?
Which part of the spinal cord is associated with the region of the lateral horn?
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What is the somatotopic organization of the anterior horn?
What is the somatotopic organization of the anterior horn?
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Where are pregnancy sympathetic motor neurons found within the spinal cord?
Where are pregnancy sympathetic motor neurons found within the spinal cord?
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Study Notes
Spinal Cord Organization
- The spinal cord begins at the foramen magnum and ends at the conus medullaris, where it transitions into the spinal cord at the plane of foramen magnum
- It ends as the conus medullaris at the interface between Lumbar vertebrae LV1 and LV2
- The spinal cord is the only "extrinsically segmented component of the CNS"—giving rise to 31 pairs of spinal nerves
- There are 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal nerve pairs
Spinal Cord Enlargements
- Cervical enlargement (C5-T1)
- Lumbosacral enlargement (L2-S3)
- The spinal cord's relationship with its surrounding anatomical structures in the dural sac
Surface Anatomy
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Ventral (anterior) surface includes the anterior median sulcus/fissure & anterior lateral sulcus/fissure
- The anterior lateral sulcus is where the ventral spinal rootlets (somatic motor) exit the spinal cord.
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Dorsal (posterior) surface includes the posterior median sulcus & posterior lateral sulcus
- The posterior lateral sulcus is where the dorsal spinal rootlets (sensory) enter the spinal cord
Cross-Sectional Anatomy
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White matter is composed of myelinated axons, stained brown using osmium-tetroxide staining
- The white matter is further divided into funiculi (or gross descriptive regions)
- Dorsal funiculus (also known as “the dorsal columns”)
- Lateral funiculus
- Anterior funiculus
- Fasciculi are defined bundles of axons (tracts) within the funiculi
- The white matter is further divided into funiculi (or gross descriptive regions)
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Gray matter is composed of neurons, glial cells, axons, and dendrites
- Divided into horns or columns
- Dorsal horn (sensory input); subdivided into head (substantia gelatinosa), neck, and base
- Ventral horn (motor output)
- Divided into horns or columns
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Commissures are bundles of axons crossing to the opposite side of the spinal cord
- Includes ventral white commissure, ventral gray commissure, & dorsal gray commissure
Regional Variation
- Cervical level: oval-shaped, large diameter, large amount of gray matter, lots of white matter , has a posterior intermediate sulcus and septum.
- Thoracic level: circular-shaped, smaller diameter than cervical, decreased gray matter area compared to cervical, and higher ratio of white matter to gray matter
- Lumbar level: larger diameter than thoracic, more white & gray matter, no posterior intermediate sulcus, and has a large substantia gelatinosa
- Sacral level: rounded shape, small diameter, more gray matter than white matter, large substantia gelatinosa, and has intermediolateral cell column containing preganglionic parasympathetic neurons
Additional Details
- Filum terminale: A non-neuronal medial filament extending from the conus medullaris to the terminal end of the dura sac.
- Lumbar cistern: The subarachnoid space within the dura sac that extends from LV1-2 to SV2 and is filled with CSF, clinically used for lumbar puncture to obtain CSF samples
- Cauda equina: Located within the lumbar cistern, contains the elongated dorsal and ventral roots of lower lumbar, sacral, and coccygeal nerves
- Intermedial zone (zona intermedia): Contains the lateral horn; prominently displayed in cross sections of thoracic and upper lumbar levels, and also seen in cross sections of the sacral level; contains preganglionic sympathetic motor neurons and preganglionic parasympathetic motor neurons at the level of S2-S4 of the spinal cord
- Somatotopic arrangement of motor neurons: arranged within the grey matter of the ventral spinal cord in three regions (flexors, extensors and axial musculature); mapped to the body
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Description
This quiz covers the organization and anatomical structure of the spinal cord, including its segments, enlargements, and surface anatomy. Understand the critical features such as spinal nerve pairs and the relationship with surrounding structures. Test your knowledge on the spinal cord's functional and structural components.
