2. or “PNS Envy” Zach London “You Can’t Make Interesting Without Teres”

3. Objective Use the motor exam to distinguish focal peripheral lesions that cause: 1.Finger drop 2.Foot drop 3.Interosseus weakness 4.Thumb weakness 5.Quadriceps weakness

4. The rules Pick a symptom (foot drop, interosseous weakness, etc.) In the left column, write relevant localizations from distal to proximal. Localizations should be a nerve, part of the plexus, or root. Fill out the chart, checking off which muscles would be weak with lesions in each localization.

5. Radial nerve (Spiral Groove) C7 root Posterior Cord Plexus Radial nerve (Axilla) Posterior Interosseus n. Shoulder Abduction Elbow extension Elbow flexion Finger extension DeltoidTriceps Brachio radialis Extensor digitorum Finger Drop

6. Deltoid (C5, C6) Triceps (C6, C7, C8) Brachioradialis (C5, C6) Extensor Digitorum Communis (C6, C7) Posterior Interosseus Radial nerve (Spiral Groove) Radial Nerve (Axilla) Posterior Cord Plexopathy

7. Deltoid (C5, C6) Triceps (C6, C7, C8) Brachioradialis (C5, C6) Extensor Digitorum Communis (C6, C7) C7 Root

8. Q: What muscle can distinguish a posterior interosseus mononeuropathy from a radial mononeuropathy at the spiral groove? A: Brachioradialis (elbow flexion with thumb up)

9. 1.Finger drop 2.Foot drop 3.Interosseus weakness 4.Thumb weakness 5.Quadriceps weakness

10. The rules, again Pick a symptom (foot drop, interosseous weakness, etc.) In the left column, write relevant localizations from distal to proximal. Localizations should be a nerve, part of the plexus, or root. Fill out the chart, checking off which muscles would be weak with lesions in each localization.

11. * Ankle plantarflexion Gastroc- nemius Common peroneal n. L5 root Lumbosacral plexus Sciatic nerve Deep peroneal n. Hip abduction Ankle inversion Ankle eversion Ankle dorsiflexion Gluteus Medius Tibialis Posterior Peroneus longus Tibialis Anterior Foot Drop * If S1 fibers are also involved

12. Tibialis Posterior (L5, S1) Peroneus Longus (L5, S1) Tibialis Anterior (L4, L5) Deep Peroneal Common Peroneal Sciatic Lumbosacral Plexus Gluteus Medius (L5, S1) Gastrocnemius (S1, S2)

13. Peroneus Longus (L5, S1) Tibialis Posterior (L5, S1) Tibialis Anterior (L4, L5) Gluteus Medius (L5, S1) Gastrocnemius (S1, S2) L5 Root

14. Q: What muscles can be used to distinguish a common peroneal neuropathy from an L5 radiculopathy? A : Tibialis Posterior (inversion) Gluteus Medius (hip abduction)

15. 1.Finger drop 2.Foot drop 3.Interosseus weakness 4.Thumb weakness 5.Quadriceps weakness

16. Medial cord plexus C8-T1 root Lower trunk plexus Ulnar nerve (elbow) Index finger extension Thumb abduction Spreading out fingers Extensor indicis Abductor pollicis brevis Interossei Interosseous Weakness

17. Abductor Pollicis Brevis (C8, T1) Extensor Indicis (C7, C8) Interossei (C8, T1) Ulnar (elbow) Medial cord plexus Lower trunk plexus or C8 Root

18. Q: What muscle can be used to distinguish an ulnar mononeuropathy at the elbow from a C8 radiculopathy? A: Abductor pollicis brevis and extensor indicis

19. 1.Finger drop 2.Foot drop 3.Interosseus weakness 4.Thumb weakness 5.Quadriceps weakness

20. C8 Root Median nerve (proximal) Anterior Interosseous nerve Median nerve (carpal tunnel) Spreading out Fingers Thumb Flexion Thumb Abduction Interossei Flexor Pollicis Longus Abductor pollicis brevis Thumb weakness

21. Abductor Pollicis Brevis (C8, T1) Flexor Pollicis Longus (C7, C8) Interossei (C8, T1) Median (carpal tunnel) Anterior Interosseus Proximal Median C8 root, medial cord or lower trunk

22. Q: What muscle can be used to distinguish carpal tunnel syndrome from a median mononeuropathy at the elbow? A: Flexor pollicis longus (Thumb flexion)

23. 1.Finger drop 2.Foot drop 3.Interosseus weakness 4.Thumb weakness 5.Quadriceps weakness

24. Quadriceps Weakness Femoral n. (above inguinal ligament) L4 root L3 root Lumbar Plexus Femoral n. (below inguinal ligament) Hip adduction Hip flexion Knee extension Adductor Longus IliopsoasQuadriceps

25. Quadriceps (L3, L4) Adductors (L2, L3, L4) Iliopsoas (L2, L3) Femoral (below inguinal ligament) Femoral (above inguinal ligament) Obturator Lumbar Plexus or L3 Root L4 Root

26. Q: What muscle can be used to distinguish a proximal femoral mononeuroapathy from a lumbar plexopathy? A: The adductor muscles

27. 1.Finger drop 2.Foot drop 3.Interosseus weakness 4.Thumb weakness 5.Quadriceps weakness Review

28. Shoulder abduction Elbow extension Elbow flexion Finger extension Which Muscles are Affected? Radial mononeuropathy at the axilla

29. Deltoid (C5, C6) Triceps (C6, C7, C8) Brachioradialis (C5, C6) Extensor Digitorum Communis (C6, C7) Radial Nerve (Axilla)

30. Ankle Eversion Ankle Inversion Ankle Plantarflexion Ankle dorsiflexion Which Muscles are Affected? L5 Radiculopathy

31. Tibialis Posterior (L5, S1) Peroneus Longus (L5, S1) Tibialis Anterior (L4, L5) Gluteus Medius (L5, S1) Gastrocnemius (S1, S2) L5 Root

32. Index finger extension Finger abduction Thumb abduction Which Muscles are Affected? Medial cord plexopathy

33. Ulnar Nerve Medial Cord Lower Trunk C8 Root Interossei

34. Median Nerve Medial Cord Lower Trunk C8 Root Abductor pollicis brevis

35. Radial Nerve Posterior Cord Lower Trunk C8 Root Extensor indicis

36. Index finger extension Finger abduction Thumb abduction Which Muscles are Affected? Medial cord plexopathy

37. Finger abduction Thumb flexion Thumb abduction Which Muscles are Affected? Anterior interosseus mononeuropathy

38. Median nerve Carpal Tunnel Abductor pollicis brevis Flexor pollicis longus Elbow Anterior Interosseus

39. Hip adduction Hip flexion Knee extension Which Muscles are Affected? L4 radiculopathy

40. Quadriceps (L3, L4) Adductors (L2, L3, L4) Iliopsoas (L2, L3) L4 Root

41. Thank You