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SEGMENTS:
Brainstem & Cranium
CN I – CN XII
The 12 Cranial Nerves Masterboard
Dual Somatic Tone
Sympathetic vs. Parasympathetic Axis
Sympathetic (Fight or Flight)
Thoracolumbar outflow (T1–L2). Postganglionic norepinephrine release activates adrenergic receptors, mobilizing immediate survival energy.
- • Pupils: Mydriasis (Dilated)
- • Heart Rate: Tachycardia & Elevated Contractility
- • Bronchioles: Bronchodilation (Max O2)
- • GI Motility: Inhibited / Sphincters Constricted
Key Neurochemistry
- Norepinephrine (NE): Primary sympathetic postganglionic transmitter acting on alpha and beta-adrenergic receptors.
- Acetylcholine (ACh): Universal preganglionic transmitter and all parasympathetic postganglionic signaling via Muscarinic (M1–M5) receptors.
- Vagus Nerve (CN X): Transmits 75% of all parasympathetic outflow to heart, lungs, and gut.
Spinal Circuits
Monosynaptic Stretch Reflex & Neuromuscular Junction
Reflex Arc Status: Baseline Rest
Synaptic Delay: ~20ms
Muscle Spindle (Ia Afferent)
Dorsal Root Ganglion
Ventral Horn Alpha Motor Neuron
Motor Endplate Contraction
Biceps Reflex
C5 – C6 Roots
Triceps Reflex
C7 – C8 Roots
Patellar (Knee-Jerk)
L2 – L4 Roots
Achilles (Ankle)
S1 – S2 Roots
Clinical Lesions
Clinical Standard
Spinal Cord & Peripheral Neuropathies
1. Brown-Séquard Syndrome
⚔️Hemicord transection causing ipsilateral motor/vibration loss and contralateral pain/temperature loss 2 levels below lesion.
2. Cauda Equina Syndrome
🚨Compression of lumbar/sacral nerve roots causing saddle anesthesia, bowel/bladder incontinence, and lower extremity weakness.
3. Bell's Palsy (CN VII LMN)
😶Peripheral Lower Motor Neuron facial palsy paralyzing entire ipsilateral hemiface, including forehead muscles (no forehead sparing).
4. Sciatica (L5–S1 Radiculopathy)
⚡Herniated nucleus pulposus compressing S1 nerve root causing shooting pain down posterior thigh and diminished Achilles reflex.
Interactive Neurological Assessment
The Neuro-Somatic Master Challenge
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