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MODULE 9:
Spinal Cord
PART 1 OF 7
MRI at last: an L4/L5 disc herniation, nucleusThe control center of the cell that contains DNA and directs cellular activities. pressing a nerve root on the left. The leg pain and L5 numbness from the Nervous Tissue module finally had a picture — months after they were dismissed.
Slide 1 Transcript
PATIENT CHART
STINA
THIS PART
Ages 35
PRESENTING WITH
Leg pain, foot numbness, disrupted reflexesAutomatic responses to stimuli.
ACTION TAKEN
Spinal Cord Stimulator Implantation
DIAGNOSIS
Cytokine-driven central sensitization
CHART CLUES
COLLECTED AS YOU GO
L4/L5 Disc Herniation Compressing a Nerve Root
Root Compression Enters at the Dorsal Horn
Diminished Ankle Reflex + L5 Radiculopathy
Sacral (S2–S4) Reflex Disrupted
Allodynia + Hyperalgesia with High IL-1β/IL-6
Neuromodulation Closes the Gate
Cytokine-Driven Central Sensitization
Put your money down: Will the picture confirm trouble at L4/L5?
The Nervous Tissue module mapped Stina’s numbness to L4/L5 from the skinThe body’s largest organ, providing protection and regulation.. Now she finally gets an MRI.
Pick the answer you believe now. We’ll come back to it later!
The Herniation That Finally Had a Picture
When Stina’s leg pain and foot numbness finally bought her an MRI, the radiologist found what no one had looked for: at the L4/L5 level, the soft center of a disc had pushed out of place and was pressing against a nerve root on the left. There, on the scan, was the source of the hot stripe down her leg and the numb band across her foot — the exact L5 territory the Nervous Tissue module had mapped. Months of “pinched nerve, give it time” suddenly had an address and an explanation.
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Slide 2 Transcript
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Slide 3 Transcript
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Discs, Roots, and the Dermatome They Serve
The vertebral column is a stack of bony vertebrae, and between each pair sits an intervertebral disc — a tough outer ring (the anulus fibrosus) around a soft gel core (the nucleus pulposus) that cushions the spineProminent ridge on the posterior scapula dividing it into supraspinous and infraspinous fossae. and lets it bend. When the outer ring tears, the gel core can herniate, bulging backward toward the spinal nerve roots that exit between the vertebrae. Press on a root and you get pain and numbness in exactly the dermatomeA specific area of skin supplied by a single spinal nerve. that root serves — which is why Stina’s L4/L5 herniation produced the L5 pattern she already had.
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Slide 4 Transcript
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Slide 5 Transcript
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Where the Map and the Chart Agree
This is where the Nervous Tissue module’s dermatome mapA diagram showing which spinal nerves correspond to specific skin regions. cashes out. The numbness that traced to L5 wasn’t abstract; it pointed straight to this disc. Anatomy and the chart agree — and now we follow the problem inside the cord the root leads to.
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Slide 6 Transcript
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FINDING!
L4/L5 Disc Herniation Compressing a Nerve Root (Left)
An L4/L5 disc herniation, its nucleus pressing a nerve root on the left — the first structural picture of the leg pain and L5 numbness the Nervous Tissue module had only mapped from the skin. New evidence gives the dermatome an image: a mechanical root compression at exactly the predicted level. (Hold it — later pages show the pain outlives this tidy structural cause.)
Confirm or refute your bet: Will the picture confirm trouble at L4/L5?
You committed to a guess: will the picture match the map? Now you know the column and the disc. Let’s read the MRI.
Slide 7 Transcript
NEXT PART
The root leads straight into the cord — so to understand what the disc threatens, we have to see how the cord is built. Next: a cross-section of the cable itself.
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All Modules
- Anatomical Language, Membranes & Homeostasis
- Just Enough Chemistry
- The Cell & Its Transport
- Making Cells & Proteins
- The Integumentary System
- The Skeletal System
- The Muscular System
- Nervous Tissue & the Senses
- The Spinal Cord
- The Brain & the Blood–Brain Barrier
- The Autonomic Nervous System
- Special Senses (in developmentThe process of growth and differentiation.)
- The Endocrine System
- Blood
- The Heart
- Blood Vessels
- The Digestive System
- The Respiratory System
- The Urinary System
- Fluids, Electrolytes & Acid–Base Balance
- The Reproductive System
- The Immune System
List of terms
- nucleus
- reflexes
- skin
- spine
- dermatome
- dermatome map
- development