Torsional Anatomy

1. Torsional Anatomy Faye Chiou Tan, MD Professor PMR, Baylor COM Chief PMR, Director EMG, HCHD

2. Disclosures • Royalties – EMG Secrets Textbook – Elsevier

3. Thanks to the Team • Dr. John Cianca • Dr. Joslyn John • Dr. Erin Furr-Stimming – Neurology • Dr. Sindhu Pandit • Dr. Katherine Taber

4. Background • Frequently we are asked to perform procedures on patients who cannot be positioned in “anatomic neutral” • Yet, anatomic references display the human body in anatomic neutral. • No anatomic references to examine where to inject in altered position

5. Anatomic neutral

6. Anatomy in motion • where do structures move to • In sports? • In movement disorders – dystonia? • In spasticity? • In contractures/ casting?

7. Anatomy in motion • The study of anatomy in the position of altered posture (ie other than anatomic neutral).

8. Torsional MSK Anatomy • Study of MSK anatomy in torsion - NEW • Definition of torsion (Merriam Webster): • 1. the twisting or wrenching of a body by the exertion of forces tending to turn one end or part about a longitudinal axis while the other is held fast or turned in the opposite direction; also : the state of being twisted • 2. the twisting of a bodily organ or part on its own axis

9. Other Torsion Examples • Testicular torsion • Intestinal torsion • Limb budding of the leg - embryology

10. Limb budding of the leg • “Anatomic neutral” is not free of torsion • Embryonic limb budding of the leg • Leg bud begins with great toe cephalad • Leg twists internally so great toe is medial • Similar to stripes on a candy cane

11. Limb budding of the leg • Eg: Plexus • Upper anterior – obturator – medial • Upper posterior – femoral – anterior • Lower anterior – tibial – posterior • Lower posterior – peroneal - anterior

12. Week 10 Gestation

13. Week 15 Gestation

14. Week 30 Gestation

15. Differentiate Torsional MSK Anatomy from Rotational • Torsional anatomy : origin and insertion turn at different rates (in the same direction) • Rotational anatomy : origin and insertion turn at the same rate (in the same direction) • Ref: Chiou-Tan FY, Cianca J, Pandit S, John J, Furr-Stimming E, Taber KH: Procedure oriented torsional anatomy of the proximal arm for spasticity injection, J Comput Assist Tomogr, 39(3): 449-452, 2015.

16. Topical Anatomy Challenges • Edema • Soft tissue • Altered anatomy (trauma, surgery) • Contractures • Spasticity

17. Overview • I. Neck • II. Arm • III. Forearm

18. Part 1:Muscles in Torticollis

19. Anatomy of Neck Injection : SCM *

20.  Fig 1a: Sternocleidomastoid – anatomic neutral position Fig 1b: Sternocleidomastoid – left torticollis position

21. Anatomy of Neck Injection: Upper trapezius *

22.  Fig 1d: Trapezius – left torticollis position

23. Take Home#1 inTorsional Anatomy • The anchored or tethered end of torsion does not move as much as the free end. • (Eg. The door hinge does not have as wide an excursion as the door knob.) • Injection sites near the tethered end will not move as much as the free end.

24. Anatomy of Neck Injection: Scalenes * *

25.  Fig 1e: Scalenes – anatomic neutral position Fig 1f: Scalenes – left torticollis position

26. Take Home#2 • Structures which were viewed easily in cross section can be difficult to view or “disappear” after torsion (i.e. are oblique) due to anisotropy. Adjusting the probe may (or may not) assist in achieving the desired view. • Eg. Cannot find the honeycomb appearance of the brachial plexus • Eg. Muscles bunch up and are not in either longitudinal or cross-sectional view.

27. Summary Torticollis NEUTRAL POSITION TORTICOLLIS POSITION Sternocleidomastoid Trapezius, Levator scapula Upper Trapezius Upper Trapezius ScalenesScalenes (Brachial plexus visible) (Brachial plexus difficult to view)

28. Part 2: Upper Arm Torsional Changes with Internal Rotation

29. Anatomy of Upper Arm Injection:Proximal – Pectoralis Major *

30.  Fig 2a: Proximal 1/3 Upper Arm Neutral Internal Rotation

31. Anatomy of Upper Arm Injection:Middle - Biceps and Brachialis *

32.  Fig 2b: Middle Upper Arm

33. Anatomy of Upper Arm Injection:Distal 1/3 and 1/6 – Biceps and Brachialis * *

34.  Fig 2c:Distal 1/3 Upper Arm Neutral Internal Rotation

35. Anatomy of Upper Arm Injection:Distal 1/6 – Radial Nerve *

36.  Fig 2d: Distal 1/6 Upper Arm Neutral Internal Rotation

37. “Rising Sun Sign” • Supination – Radial nerve is lateral • Pronation – Radial nerve is anterior • Ref: Chiou-Tan FY, Cianca J, Pandit S, John J, Furr-Stimming E, Taber KH: Procedure oriented torsional anatomy of the proximal arm for spasticity injection, J Comput Assist Tomogr, 39(3): 449-452, 2015.

38. Summary Upper Arm

39. Part 3: Forearm Changes with Internal Torsion

40. Supination/Pronation • Study of supination/pronation dates to 1800’s • Broken forearm bones that healed had limited supination/pronation • “Functional alignment” of bones • Both radius and ulna move, but not to same degree.

41. Supination/Pronation Refs • Duchenne GB. Physiology of Motion, Demonstrated by Means of Electrical Stimulation and Clinical Observation and Applied Study of Paralysis and Deformities. Philadelphia: Lippincott, 1949 • Heibern J. Movements of the ulna in rotation of the fore-arm. J Anat Physiol. 1855; 19:237-240. • Dwight T. The movement of the ulna in rotation of the fore-arm. J Anat Physiol. 1855; 19:186-189. • Weinberg AM, Pietsch IT, Helm MB, et al. A new kinematic model of pro- and supinaton of the forearm. J Biomech. 2000; 33:487-491. • Nakamura T, Yabe Y, Horiuchi Y et al. Three dimensional MRI of interosseous membrane of forearm: a new method using fuzzy reasoning. Magn Reson Imaging. 1999; 17:463-470.

42. Pronator Teres *

43. Pronator Teres  Neutral Medial Rotation

44. Flexor Carpi Radialis *

45. FCR  Neutral Medial Rotation

46. FCU/FDP *

47. FCU and FDP  Neutral Medial Rotation

48. Brachioradialis * *

49. Brachioradialis (BR)  Neutral Medial Rotation

50. Flexor Digitorum Superficialis *