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Questions and Answers
Which part of the spinal cord marks the end of the spinal cord proper and gives off the lower spinal nerves?
Which segment of the spinal cord typically corresponds to the level of the first lumbar vertebra?
What is the region of spinal cord that is responsible for innervation of the upper limbs?
Which part of the spinal cord is a thin, non-neural filament that extends from the conus medullaris and anchors it to the coccyx?
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At what vertebral level does the cervical enlargement of the spinal cord usually extend?
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Which part of the spinal cord contains more gray matter due to its function in supplying nerve fibers for the upper limbs?
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Which part of the spinal cord contains more white matter due to its function in transmitting sensory information from the lower limbs?
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What is another term for C1-C5 spinal nerves in anatomical terminology?
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Which region of the spinal cord is responsible for innervation of structures like abdominal muscles and external genitalia?
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The lumbar nerves usually exit from which vertebral level?
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Study Notes
Spinal Cord Structure
- The spinal cord consists of grey matter and white matter in a cross-section
- Grey matter is composed of cell bodies, including dorsal horn, ventral horn, and lateral horn
- White matter surrounds grey matter and consists of myelinated axons that form tracts
Spinal Cord Enlargements
- Cervical enlargement: receives upper limb nerves from C5-T1 segments
- Lumbosacral enlargement: receives lower limb nerves from L2-S3 segments
Brachial Plexus
- Forms from cervical enlargement (C5-T1 segments)
- Consists of roots, trunks, divisions, cords, and terminal branches
- Includes median, ulnar, and radial nerves that innervate muscles, joints, and skin of the upper limb
Lumbar Plexus and Sacral Plexus
- Lumbar plexus: forms from lumbosacral enlargement (L1-L4 segments)
- Sacral plexus: forms from lumbosacral enlargement (L4-S4 segments)
- Both plexuses innervate muscles, joints, and skin of the lower limb
Association Neurons and Motor Neurons
- Association neurons (interneurons) are found within the spinal cord
- Motor neurons have a cell body, dendrites, and a long axon that transmits impulses from the CNS
Spinal Meninges
- Three layers of spinal meninges: dura mater, arachnoid mater, and pia mater
- Extradural space (epidural): external to dura mater, where epidural anesthesia is administered
- Subarachnoid space: between pia and arachnoid mater, containing CSF
Reflex Arcs
- Stretch reflexes involve a receptor, sensory neuron, integration center, motor neuron, and effector
- Example: flexion withdrawal reflex
Autonomic Nervous System (ANS)
- Supplies smooth muscle, glands, and viscera
- Divided into sympathetic and parasympathetic nervous systems
- ANS motor pathways require two neurons to carry impulses from the CNS to target tissues
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Description
Test your knowledge on the structure of the spinal cord in cross-section, including grey and white matter, spinal cord enlargements, and plexuses such as brachial and lumbosacral. Identify the main components and their functions.
