Nerve vs Root Lesions

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Sometimes they want you to pick the specific nerve, othertimes the root.

Shoulder/Arms/Hands

1. Wrist drop = radial nerve
2. Carpal tunnel = median nerve at wrist (no.1 site) transverse carpal ligament. Treatment is always 1st night-time wrist brace.
3. Cubital tunnel = ulnar nerve at elbow (no.1 site)
4. Guyon Canal = ulnar nerve at wrist (usually a habitual cyclist)
5. Fall on outstretched hand if wrist hurts = scaphoid fx. always thumb spica splint. can x-ray. if negative = spica splint then repeat x-ray in a week
6. Fall on outstretched hand if upper arm hurts = supracondylar fx. Most common in kids and most commonly affects median nerve and brachial artery.
7. Fall on outstretched hand if shoulder hurts and/or can't move shoulder = dislocation (axillary artery). If can move shoulder, albeit painful and require active assistance = radial cuff tear.
8. Very active person with limited shoulder motion = supraspinatous tendinopathy (+ Neer's Test) vs. acromial bursitis vs. adhesive capsulitis (can't move at all).
9. Know your sensory innervation. of median, ulnar, radial, lateral antebrachial cutaneous, medial antebrachial cutaneous, axillary (deltoid)
10. Thoracic outlet syndrome, SVC compression syndrome, superior sulcus tumor

Legs/Feet
1. Can't flex hip = either iliopsoas or quads(rectus femoris femoral n.)
2. Can't extend hip = hamstrings (sciatic n.)
3. Can't extend knee = quads (femoral n.) L3, L4 kick the door
4. Can't flex the knee = calves (tibial n.)
5. Can't evert the feet = peroneal muscles (superficial peroneal n.)
6. Can't dorsiflex the feet aka can't heel walk = tibialis anterior (deep peroneal n.) L5
7. Can't plantar flex the feet aka can't tiptoe = calf mm. i.e. gastroc, soleus (tibial n.)

Sensation.
1. top of thigh = femoral n.
2. medial thigh = obturator n. / medial femoral cutaneous
3. lateral thigh = femoral n.
4. bottom thigh = sciatic (posterior femoral cutaneous)
5. lateral leg = common peroneal (fibular) n.
6. posterior leg = tibial nerve
7. medial leg = saphenous nerve
8. sole of foot including (BIG Tole bottom) = tibial n. and its branches = medial plantar nerve, lateral plantar nerve.
9. Dorsum of foot including (BIG Tole top) = common peroneal n. specifically, if they ask for sensation of webspace between big toe and 2nd toe = deep peroneal nerve (L5)
10. Side strike fibula head most commonly results in common peroneal n. injury
11. Injury to back of knee most commonly results in tibial n. injury



A word about DISC HERNIATION. Except for the C8-T1, herniation between two vertebrae compresses the 2nd number. Example: L4-L5 affects L5 root. L5-S1 affects S1 root.
1. L3, L4 roots flex your quads and kicks the door, i.e. patellar knee jerk reflex (L4). so L3-L4 herniation = weak knee extension, numbness on anterior thigh and absent or weak patellar reflexes

2. L4-L5 roots dorsiflex your feet and toes, i.e. similar to common peroneal nerve. So L4-L5 herniation = can't walk on heels or give "big toe thumbs up" i.e. extensor hallucis longus and numbness on dorsum of feet

3. L5-S1 for calf mm. = tiptoe, also Achilles tendon reflex, so L5-S1 herniation affects S1 = pain radiating down thigh, side of leg, lateral side of feet and sole of feet, weak plantarflexion and decreased achilles reflex.

Finally in root radiculopathy vs. peripheral nerve. Radiculopathy usually involves radiating pain, +/-paresthesia in dermatomal distribution, +/-paresis in myotomal distribution. and possible + straight leg test.