Questions and Answers
Which of the following is NOT a function of the arachnoid mater?
Where is the cerebrospinal fluid (CSF) located?
Which of the following structures is responsible for transmitting nociceptive impulses to the brain?
What is the main function of the anterior spinal artery?
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Which of the following is NOT a segmental vessel that contributes to the blood supply of the spinal cord?
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What is the primary function of the lower motor neurons located in the ventral horn of the spinal cord?
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What is the term for the space between the dura mater and the arachnoid mater?
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Which of the following procedures involves the introduction of anesthetics into the epidural space?
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What is the function of the dorsal roots of spinal nerves?
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Which segments of the spinal cord contribute to the cervical enlargement?
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What structure is formed by the strands of connective tissue that extends from the conus medullaris?
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How many spinal nerves are there in total?
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What does the cauda equina consist of?
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Which of the following pairs are the spinal veins that run in the midline?
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Study Notes
Venous Drainage
- 6 longitudinal interconnecting veins in the spinal cord, including: • Anterior spinal vein: runs in the midline • Posterior spinal vein: runs in the midline • Anterolateral spinal veins (2) • Posterolateral spinal veins (2)
- Anterolateral and posterolateral veins are situated near the lines of attachment of ventral and dorsal nerve roots
Enlargements of Spinal Cord
- 2 main enlargements: • Cervical enlargement: consists of cord segments C3-T1 and provides innervation for the upper limb via the brachial plexus (C5-T1) • Lumbar enlargement: made up of segments L1-S3 and associated with innervation of the lower limb via the lumbar plexus (L1-L4) and sacral plexus (L4-S2)
Conus Medullaris and Filum Terminale
- Conus medullaris: conical termination of the spinal cord
- Filum terminale: strand of connective tissue from the tip of the conus medullaris, extending caudally and attaching to the dorsal surface of the 1st coccygeal vertebra
Spinal Nerves
- 31 bilaterally paired spinal nerves: • 8 cervical • 12 thoracic • 5 lumbar • 5 sacral • 1 coccygeal
- Spinal nerves attach to the spinal cord as dorsal and ventral roots
- Dorsal roots carry afferent fibers
- Ventral roots carry efferent fibers
- Cauda equina: lumbar and sacral roots descending below the termination of the cord in a leash-like arrangement
Arachnoid Mater
- Translucent membrane investing the cord like a loose-fitting bag
- Subarachnoid space: lies between the pia and arachnoid mater, containing cerebrospinal fluid (CSF)
Dura Mater
- Tough, fibrous membrane enveloping the cord loosely
- Separated from the arachnoid by the subdural space
- Separated from the bony wall of the vertebral canal by the epidural space
- Notes: • Although the spinal cord terminates at vertebral level L1-2, the arachnoid and dural sheaths continue caudally to S2 • Spinal nerve roots pass towards their intervertebral foramina, evaginating the arachnoid and dura to form meningeal root sleeves • Arachnoid and dura become continuous with epineurium ensheathing the spinal nerve
Internal Structure of Spinal Cord
- Incompletely divided into 2 symmetrical halves by the dorsal median sulcus and ventral median fissure
- Central canal: small canal in the center of the cord, continuous rostrally with the cerebral ventricular system
- Grey matter: • Surrounds the central canal • Consists of nerve cell bodies, dendrites, and synaptic contacts • Dorsal horn: main site of primary afferent fibers, including substantia gelatinosa (important for transmission of nociceptive impulses to the brain) • Lateral horn: contains preganglionic sympathetic neurons • Ventral horn: contains alpha and gamma motor neurons (lower motor neurons)
- White matter: contains ascending and descending nerve fibers
Blood Supply of Spinal Cord
- Arterial supply: • 3 longitudinal vessels run the length of the spinal cord: • Anterior spinal artery: arises from 2 vertebral arteries, descends along the ventral surface of the cord in the midline • Posterior spinal arteries: arise from vertebral arteries or posterior inferior cerebellar arteries, run on the posterolateral surface of the cord • Radicular arteries: derived from segmental vessels, pass through intervertebral foramina and divide into anterior and posterior branches
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Description
This quiz covers the venous drainage of the spinal cord, including the 6 longitudinal interconnecting veins and their roles. It also touches on enlargements of the spinal cord and their functions.