Download BIOMECHANICS APPLICATIONS

Upper Extremities Parts
Shoulder Girdle
Shoulder Joint
Elbow Joint
Radioulnar Joint
Wrist Joint
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
Shoulder Girdle
Involved in Reaching/Grasping Motions
Designed for Mobility
Unstable joint
Strength of Muscles VERY important
Shoulder Joint
Involved in a wide variety of motions
Designed for Mobility, Unstable joint
Rotator Cuff & Deltoids = small angle pull
Wheel-Axle Mechanism
Overarm Throw Pattern
“cocking action” = extreme lateral rotation
rapid medial rotation and protraction
Strengthen Medial Rotators BOTH
Concentrically and Eccentrically
Elbow Joint
Only Flexion and Extension
Stable joint due to bony structure
Muscle arrangement = stabilizing effect
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
3 Ways to Strengthen Elbow Flexors
1.
Elbow flexion from
anatomical position
2.
Elbow flexion with
shoulder Hyperextended
3.
shoulder flexion
figure 2.5j on pg 62 
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 pronated
page 185 right side of picture supinated
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
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
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
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]
Knee Joint: Potential Injury Positions
page 205
Knee Joint: Potential Injury Positions
turning the body
while foot is fixed
FIG 6.8 page 200
Knee Joint: Potential Injury Positions
Deep Squat
changing axis of rotation
from knee joint
to
calf/thigh area
FIG 6.11 page 204
Knee Joint: Potential Injury Positions
rehabilitation of knee injuries
page 260: studies on ACL stress, shear forces, petellofemoral contact
ANKLE JOINT
Bony arrangement = stability
Ligaments play major role in stability
flexion = dorsiflexion
extension = plantar flexion
FIG 6.13
page 207
SUBTALAR JOINT
allows foot to navigate uneven surfaces
inversion (sole in) and eversion (sole out)
inversion with plantar flexion
eversion with dorsiflexion
FIG 6.15
page 209
Inversion during Plantar Flexion
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
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
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
Walking
LOCOMOTION
Running
Long support phase
[65%]
Shorter support phase
always support phase
non-support phase
F vertical = 3 x body wt
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 6.19
page 213
Ideal Alignments: FOOT
FIG 6.20
page 214
a is Ideal
FIG 6.21
Leg Length Inequities
Anatomical - due to bone structure
Functional - due to tilted pelvis
Environmental - due to uneven ground
Femoral
Femur rotated medial
medial facing patella
frequent in FEMALES
treatment:
1. Strengthen lateral hip
rotators
2. Stretch medial hip
rotators
TORSION
Tibial
Tibia rotated lateral
lateral facing patella
frequent in MALES
treatment:
- muscular balance in all
3 hamstrings must be
developed
VARUS
INWARD angle
from proximal to
distal

 lateral
stress is
proximal
 medial
distal
stress is
VALGUS
OUTWARD angle
from proximal to
distal

 medial
stress is
proximal
 lateral
distal
stress is
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