Understanding Upper Extremity Joints & Muscles

1. Upper Extremities Parts • Shoulder Girdle • Shoulder Joint • Elbow Joint • Radioulnar Joint • Wrist Joint

2. Muscle Contribution to Joint • Stronger Muscles = More Joint Stability • Angles of Pull influence Joint Stability • Stabilizing Angles = < 90 angle of pull • Dislocating Angles = > 90 angle of pull

3. Shoulder Girdle • Involved in Reaching/Grasping Motions • Designed for Mobility • Unstable joint • Strength of Muscles VERY important

4. Shoulder Joint • Involved in a wide variety of motions • Designed for Mobility, Unstable joint • Rotator Cuff & Deltoids = small angle pull • Wheel-Axle Mechanism

5. Overarm Throw Pattern • “cocking action” = extreme lateral rotation • rapid medial rotation and protraction • Strengthen Medial Rotators BOTH Concentrically and Eccentrically

6. Elbow Joint • Only Flexion and Extension • Stable joint due to bony structure • Muscle arrangement = stabilizing effect

7. How to Strengthen Elbow Extensors • Elbow Extensions with shoulder flexed figure 2.5e on page 61 • Shoulder Hyperextensions with elbow extended figure 2.5d on page 61

8. 3 Ways to Strengthen Elbow Flexors • Elbow flexion from anatomical position • Elbow flexion with shoulder Hyperextended • shoulder flexion figure 2.5j on pg 62 

9. Radioulnar Joint • Unstable due to weak bony arrangement • Pronate = turn inward [medial] away from anatomical position • Supinate = turn outward [lateral] back toward anatomical position figure 5.12 left side of picture pronatedpage 185 right side of picture supinated

10. Wrist Joint • MSDs - musculoskeletal disorders 1. angle of the work surface 2. position requirements of the work 3. magnitude & direction of applied forces 4. Degree of repetition • CTS - Carpal Tunnel Syndrome • see Force guidelines per task on page 189

11. Hip Joint • Medial rotation involved in kick, throw & strike • Wheel-Axle - figure 6.5 and 6.6 [page 197] A: medial B: lateral hip rotation

12. Hip Joint • Bending/Stooping = increase FA resistive • to achieve equilibrium, hip extensors must provide high Tension/Force [hams, back] FIG 9-30 page 296 “Basic Biomechanics”4th Edition by Susan J. Hall

13. Knee Joint • Biarticulate Muscles - work knee and hip • Muscular Imbalances: 1. Hams - lateral vs. medial lateralis 2. Quads - vastus lateralis and medialis • Positions for potential injury 1. Foot fixed while hip/trunk rotates 2. Squats [FIG 6.11 pg 204] 3. Whip kick in Breaststroke [FIG 6.12 pg 205]

14. Knee Joint: Potential Injury Positions page 205

15. Knee Joint: Potential Injury Positions turning the bodywhile foot is fixed FIG 6.8 page 200

16. Knee Joint: Potential Injury Positions Deep Squatchanging axis of rotationfrom knee jointtocalf/thigh area FIG 6.11 page 204

17. Knee Joint: Potential Injury Positionsrehabilitation of knee injuries page 260: studies on ACL stress, shear forces, petellofemoral contact

18. ANKLE JOINT • Bony arrangement = stability • Ligaments play major role in stability • flexion = dorsiflexion • extension = plantar flexion FIG 6.13page 207

19. SUBTALAR JOINT • allows foot to navigate uneven surfaces • inversion (sole in) and eversion (sole out) • inversion with plantar flexion • eversion with dorsiflexion FIG 6.15page 209Inversion during Plantar Flexion

20. Muscles of Ankle & Foot • Strength important on all sides • Muscular imbalance = misalignment • misalignment = line of g eccentric to joints • weak dorsiflexors may cause shin splints • overdeveloped inversion/plantar flexion muscles = prone to lateral ankle sprains

21. Stretching Achilles Tendon • Preventative measure for shin splints • Achilles tendon = extension of both gastrocnemius and soleus muscles • 2 dorsiflexion stretches: 1. with knee extended 2. with knee flexed

22. Plantar Fasciitis • Overuse Syndrome injury • overload of stress at insertion of plantar surface fascia on calcaneous • chronic therapy involves: 1. Strengthen plantar & dorsiflexors 2. Increase ROM in dorsiflexion see page 210 re Kibler et al study

23. Long support phase [65%] always support phase Shorter support phase non-support phase F vertical = 3 x body wt LOCOMOTION Walking Running

24. Ideal Alignments: LEG • Lower extremities like columns supporting a roof • Ideally as vertically aligned and as straight as possible to support the forces from above FIG 6.19page 213

25. Ideal Alignments: FOOT FIG 6.20page 214 a is IdealFIG 6.21

26. Leg Length Inequities • Anatomical - due to bone structure • Functional - due to tilted pelvis • Environmental - due to uneven ground

27. Femur rotated medial medial facing patella frequent in FEMALES treatment: 1. Strengthen lateral hip rotators 2. Stretch medial hip rotators Tibia rotated lateral lateral facing patella frequent in MALES treatment: - muscular balance in all 3 hamstrings must be developed TORSION Femoral Tibial

28. VARUS • INWARD angle from proximal to distal • lateral stress is proximal • medial stress is distal

29. VALGUS • OUTWARD angle from proximal to distal • medial stress is proximal • lateral stress is distal

30. Key Features of Good Shoes • Heel well cushioned • Heel Counter firm • Arch Support firm • Sole Width reasonable for stability • Forefoot flexible & cushioned • Toe Box with reasonable room • Traction, Durability, Permeability