H-Reflex Cheat Sheet 🔥 1) The Golden Rule Orthodromic = impulse… — هبد تخصص DPT - NU — TG.ME

H-Reflex Cheat Sheet 🔥 1) The Golden Rule Orthodromic = impulse travels in the normal physiological direction Antidromic = impulse travels in the opposite direction That’s it 😎 ⸻ 2) In Sensory Fibers Normal direction: Receptor → Spinal Cord So: ✅ Toward spinal cord = Orthodromic ❌ Away from spinal cord = Antidromic ⸻ Example Foot → Spinal Cord ✅ Orthodromic sensory impulse ⸻ 3) In Motor Fibers Normal direction: Spinal Cord → Muscle So: ✅ Toward muscle = Orthodromic ❌ Toward spinal cord = Antidromic ⸻ Example Spinal Cord → Soleus ✅ Orthodromic motor impulse ⸻ 4) H-Reflex Pathway Low stimulus stimulates: ✅ Ia sensory fibers only ⸻ Step 1 Ia fiber → Spinal Cord Sensory ✅ Orthodromic ⸻ Step 2 Synapse occurs ⸻ Step 3 Spinal Cord → Muscle Motor ✅ Orthodromic ⸻ Result: ✅ H-reflex appears ⸻ Important Point 🚨 The sensory impulse DOES NOT return to the muscle. ❌ Wrong: Sensory impulse goes up then comes back down ✅ Correct: Sensory impulse goes up ↓ Synapse ↓ NEW motor impulse goes down ⸻ Why Does M-Wave Appear? When stimulus intensity increases: The stimulator now activates: ✅ Ia sensory fibers AND ✅ Motor axons directly ⸻ Direct motor stimulation creates: Stimulator → Muscle Motor ✅ Orthodromic This produces: 🔥 M-wave ⸻ Why Does H-Reflex Decrease? The same motor axon also sends another impulse: Stimulator → Spinal Cord Motor ❌ Antidromic ⸻ Now we have: H reflex Spinal Cord ↓ ↓ ↓ Muscle Orthodromic AND Motor impulse ↑ ↑ ↑ Spinal Cord Antidromic ⸻ 💥 COLLISION They hit each other. Result: ⬇️ H-reflex decreases ⬆️ M-wave increases ⸻ High Yield Exam Points 🔥 Sensory Fiber Toward spinal cord = Orthodromic Away from spinal cord = Antidromic ⸻ Motor Fiber Toward muscle = Orthodromic Toward spinal cord = Antidromic ⸻ H-Reflex Sensory + Synapse + Motor ✅ True reflex ⸻ F-Wave Motor only ❌ Not a true reflex ⸻ A-Wave Not a reflex Usually suggests reinnervation ⸻ Stimulus Intensity Low stimulus ➡️ H only Medium stimulus ➡️ H + M High stimulus ➡️ H decreases + M increases Supramaximal stimulus ➡️ H disappears + M becomes maximal ⸻ One Sentence to Remember 🧠 For sensory nerves, orthodromic goes to the spinal cord. For motor nerves, orthodromic goes to the muscle. Antidromic is the opposite direction. 🔥