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What are the key structural features of the external aspect of the spinal cord?
Located in the back and neck regions, elongated cylindrical shape, located in the vertebral canal, approximately 45 cm long.
What is the internal organization of the spinal cord?
Common arrangement of grey and white matter.
Which of the following are white matter tracts found in the spinal cord? (Select all that apply)
What functions does the spinal cord serve?
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Where does the spinal cord extend from and end in adults?
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What are the two enlargements of the spinal cord?
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What are the three layers of the spinal meninges?
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The cauda equina is a bundle of nerve roots located at the termination of the spinal cord.
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What is the composition of grey and white matter in the spinal cord?
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What are the types of tracts based on their direction in the spinal cord?
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Match the following spinal cord functions with their descriptions:
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Study Notes
Spinal Cord: Function and Location
- The spinal cord carries signals between the brain and the body
- The pathway for messages sent by the brain to the body and from the body to the brain.
- It is responsible for motor, sensory and autonomic information.
- Acts as a reflex centre for basic reactions
- Located in the back and neck regions
- Elongated cylindrical shape
- Located in the Vertebral canal
- Approximately 45 cm long
- Extends from the Brainstem (medulla oblongata)
- Ends at L2 in adults (L3 at birth)
Spinal Cord: Anatomical Features
-
Enlargements: These are a result of the increased volume of motor cells in the ventral horns of the grey matter.
- Cervical
- Lumbosacral
- Conus medullaris: The tapered end of the spinal cord which ends at L2.
-
Cauda equina: Lower nerve roots progressively elongated, forming a bundle within the dural sac (reaching S2). Implications:
- Lumbar puncture: To diagnose serious infection, Multiple Sclerosis (MS)
- Epidural anesthesia: Pain relief
- Spinal Anaesthetic: Injection of numbing medicine directly into the fluid sac
- Filum terminale: A fibrous extension of the pia mater that attaches the conus medullaris to the coccyx.
Spinal Nerves
- 31 pairs of spinal nerves, each composed of:
- Anterior (ventral) & Posterior (dorsal) Rootlets
- Anterior (ventral) & Posterior (dorsal) Roots
- (motor)
- (sensory)
-
Mixed Spinal Nerve: These form in the Intervertebral foramen.
- Ventral (anterior) primary rami
- Dorsal (posterior) primary rami
Internal Organisation of the Spinal Cord
- Composed of:
-
Grey Matter: Centrally located, forming an 'H' shape.
- Grey Commisures: Connect the two halves of the grey matter.
-
Extensions:
- Ventral Horns (2): Contain motor neurons.
- Dorsal Horns (2): Contain sensory neurons.
- White Matter: Located outside of the grey matter.
- Central canal: Located in the centre of the grey matter.
-
Grey Matter: Centrally located, forming an 'H' shape.
Fissures and Sulci
- Anterior Median Fissure: A deep groove on the ventral surface of the spinal cord.
- Posterior Median Sulcus: A shallow groove on the dorsal surface of the spinal cord.
- Posterolateral Sulcus: A groove on the dorsal lateral surface of the spinal cord.
Grey Matter
- Subdivided into laminae (‘Rexed’s laminae’):
- I – X (dorsal – ventral)
- IX (most important): Cell bodies of motor neurons to skeletal muscle.
White Matter
- Highly organised:
- Ascending and descending nerve fibres: Run between the spinal cord and the brain.
-
Columns (funiculi):
- Anterior (ventral)
- Lateral
- Posterior (dorsal)
- Tracts (fasciculi):
- Partial spinal cord lesions: Can cause regional loss of function depending on the affected area.
Ascending and Descending Tracts
- Ascending tracts: Sensory pathways that begin at the spinal cord and stretch up to the cerebral cortex.
- Descending tracts: Pathways by which motor signals are sent from the brain to lower motor neurons in the spinal cord.
Spinal Cord Arterial Supply and Venous Drainage
-
Arterial supply:
- Major vessels include the Anterior Spinal Artery and Posterior Spinal Arteries
- Supplied by arteries arising from the vertebral, cervical, thoracic, lumbar and sacral arteries
-
Venous drainage:
- By numerous veins that form the Anterior Spinal Vein and Posterior Spinal Vein
- Drain into the vertebral, intercostal, lumbar, and sacral veins
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Description
This quiz explores the structure and function of the spinal cord, including its role in neural signaling and reflex actions. It covers key anatomical features, such as enlargements, the conus medullaris, and the cauda equina. Test your knowledge on the spinal cord's location and its significance in the nervous system.
