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Questions and Answers
What is the primary role of the spinal cord?
What is the primary role of the spinal cord?
Which regions of the spinal cord correspond to the cervical, thoracic, lumbar, sacral, and coccygeal sections?
Which regions of the spinal cord correspond to the cervical, thoracic, lumbar, sacral, and coccygeal sections?
What is the function of the cauda equina?
What is the function of the cauda equina?
What primarily constitutes the white matter of the spinal cord?
What primarily constitutes the white matter of the spinal cord?
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What is found in the anterior/ventral root of a spinal nerve?
What is found in the anterior/ventral root of a spinal nerve?
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How are spinal nerves classified in terms of their function?
How are spinal nerves classified in terms of their function?
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Which spinal column region has the highest number of spinal nerves?
Which spinal column region has the highest number of spinal nerves?
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What is the primary function of the dorsal ramus?
What is the primary function of the dorsal ramus?
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Which ramus is specifically involved in the formation of plexuses?
Which ramus is specifically involved in the formation of plexuses?
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What type of fibers are found in rami communicantes?
What type of fibers are found in rami communicantes?
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What does the sympathetic trunk consist of?
What does the sympathetic trunk consist of?
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Which structures are innervated by intercostal nerves?
Which structures are innervated by intercostal nerves?
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What is the primary function of a nerve plexus?
What is the primary function of a nerve plexus?
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Which of the following spinal nerves make up the brachial plexus?
Which of the following spinal nerves make up the brachial plexus?
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What structure is located between the dura mater and the arachnoid mater?
What structure is located between the dura mater and the arachnoid mater?
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Which nerve is considered the most important in the cervical plexus?
Which nerve is considered the most important in the cervical plexus?
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Which layer of meninges is described as a tough, outermost layer?
Which layer of meninges is described as a tough, outermost layer?
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What is referred visceral pain?
What is referred visceral pain?
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Which ventral rami are part of the lumbar plexus?
Which ventral rami are part of the lumbar plexus?
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What is a dermatome?
What is a dermatome?
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What is the primary function of the filum terminale in the spinal cord?
What is the primary function of the filum terminale in the spinal cord?
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Which structure within the spinal cord contains a cluster of neuron cell bodies?
Which structure within the spinal cord contains a cluster of neuron cell bodies?
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What is found primarily in the anterior/ventral horns of the spinal cord?
What is found primarily in the anterior/ventral horns of the spinal cord?
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What type of neurons are primarily located in the lateral horns of the spinal cord?
What type of neurons are primarily located in the lateral horns of the spinal cord?
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What is the function of the gray commissure in the spinal cord?
What is the function of the gray commissure in the spinal cord?
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Which of the following is NOT found in the gray matter of the spinal cord?
Which of the following is NOT found in the gray matter of the spinal cord?
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In which regions of the spinal cord are lateral horns found?
In which regions of the spinal cord are lateral horns found?
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What structures are found in the white matter of the spinal cord?
What structures are found in the white matter of the spinal cord?
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What kind of fluid is found in the central canal of the spinal cord?
What kind of fluid is found in the central canal of the spinal cord?
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What direction do ascending tracts in the spinal cord primarily carry sensory information?
What direction do ascending tracts in the spinal cord primarily carry sensory information?
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Study Notes
Overview of Spinal Cord and Spinal Nerves
- The spinal cord transmits sensory information from the body to the brain and motor commands from the brain to the body. It also coordinates reflexes (automatic responses to stimuli).
- Spinal nerves connect the central nervous system (CNS) to peripheral body parts, enabling voluntary and involuntary muscle control and communication with sensory organs.
Spinal Cord Regions
- The spinal cord has cervical, thoracic, lumbar, sacral, and coccygeal regions.
- Each region corresponds to a specific section of the vertebral column and controls specific body parts.
Conus Medullaris and Cauda Equina
- The conus medullaris is the tapered end of the spinal cord, near L1-L2.
- The cauda equina extends from the conus medullaris to the sacral and coccygeal regions, resembling a horse's tail.
White Matter of the Spinal Cord
- Myelinated axons organized into tracts conduct nerve impulses for sensory and motor pathways between the brain and the body.
Posterior/Dorsal Root, Ganglion, and Ventral Root
- The posterior (dorsal) root contains sensory fibers carrying information to the spinal cord.
- The posterior (dorsal) root ganglion houses sensory neuron cell bodies.
- The anterior (ventral) root contains motor fibers that transmit commands from the spinal cord to muscles.
Spinal Nerves
- Spinal nerves are mixed nerves, containing sensory and motor fibers.
Spinal Nerve Counts
- Cervical: 8
- Thoracic: 12
- Lumbar: 5
- Sacral: 5
- Coccygeal: 1
Dorsal Ramus
- The dorsal ramus innervates muscles and skin of the back.
Ventral Ramus
- The ventral ramus forms plexuses.
Rami Communicantes, Sympathetic Trunk, Ganglion
- Rami communicantes carry sympathetic nerve fibers.
- The sympathetic trunk is a chain of interconnected sympathetic ganglia.
- Sympathetic trunk ganglia contain sympathetic neuron cell bodies.
Dermatomes
- A dermatome is a region of skin innervated by a single spinal nerve.
Referred Visceral Pain
- Referred visceral pain originates from internal organs but is perceived as coming from a different area due to shared neural pathways.
Nerve Plexuses
- Nerve plexuses are networks of interwoven spinal nerves.
- They provide redundancy, meaning if one nerve is damaged, others can compensate.
- Cervical, brachial, lumbar, and sacral areas form plexuses.
Intercostal Nerves
- Intercostal nerves innervate intercostal muscles, abdominal wall muscles, and overlying skin.
Cervical Plexus
- The cervical plexus is formed by ventral rami of C1-C4 nerves.
- It innervates the neck, shoulder, and diaphragm.
- The phrenic nerve is important.
Brachial Plexus
- The brachial plexus is formed by ventral rami of C5-T1 nerves.
- It innervates the shoulder, arm, forearm, and hand.
Lumbar Plexus
- The lumbar plexus is formed by ventral rami of L1-L4 nerves.
- It innervates the abdominal wall, anterior thigh, and medial thigh.
Sacral Plexus
- The sacral plexus is formed by ventral rami of L4-S4 nerves.
- It innervates the pelvis, posterior thigh, leg, and foot. The largest nerve is the sciatic nerve (which splits into tibial and common fibular nerves).
Protection and Support of the Spinal Cord (Meninges)
- The meninges (protective membranes) in order from superficial to deep are: dura mater, arachnoid mater, and pia mater.
- The dura mater is the outermost, tough layer.
- The pia mater is the innermost, thin, and vascular layer that adheres to the spinal cord.
- The arachnoid mater is the middle layer.
- Epidural, subdural, and subarachnoid spaces are located between these layers.
Spinal Cord Anatomy
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Nucleus (in CNS): a cluster of neuron cell bodies within the CNS.
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Gray matter of spinal cord: contains cell bodies, dendrites, and unmyelinated axons.
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Anterior/ventral horns: somatic motor neuron cell bodies (for skeletal muscles).
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Lateral horns: autonomic motor neuron cell bodies (for visceral organs).
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Posterior/dorsal horns: interneurons and sensory neuron axons (process sensory input).
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Gray commissure: connects the two sides of the spinal cord
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Central canal: contains cerebrospinal fluid (CSF)
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White matter of spinal cord: myelinated axons organized into tracts.
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Tracts: bundles of axons in the CNS. Posterior, lateral and anterior funiculi
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Sensory (ascending) tracts: toward the brain
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Motor (descending) tracts: away from the brain
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Description
This quiz covers the anatomy and functions of the spinal cord and spinal nerves. Learn about the regions of the spinal cord, the conus medullaris, and cauda equina, as well as the role of white matter in nerve impulse conduction.