Transcript Lower Extremit Structure and Function

Muscles and Movements of
Lower Extremity – Ch 8
Objectives
• Explain how anatomical structure affects
movement capabilities of lower extremity
articulations.
• Identify factors influencing the relative mobility
and stability of lower extremity articulations.
• Explain the ways in which the lower extremity is
adapted to its weightbearing function.
• Identify muscles that are active during specific
lower extremity movements.
• Describe the biomechanical contributions to
common injuries of the lower extremity.
Lower Extremity Outline
• Hip Joint
– Structure , Loads, and Muscles and Movements
• Knee Joint
– Structure, Loads, Muscles and Movements
– Common knee injuries – patellar chondromalacia (a.k.a. runners
knee) and anterior cruciate tear
• Ankle Joint
– Structure, Muscles and Movements
– Common ankle and foot injuries - plantar fascitis, pronated feet
• Misalignment problems of lower extremity
• Websites
• Homework
Hip joint
structure:
Front View
Loads on the Hip
• During swing phase of walking:
– Compression forces on hip greater than body weight
(due to muscle tension) 250% body weight (BW)
• Increases with hard-soled shoes
• Increases with gait increases (both support and
swing phase) (500% BW when running 3.5 m/s)
• Body weight, impact forces translated upward thru
skeleton from feet and muscle tension contribute
to compressive load on hip.
Compressive forces on hip jt
Socket while walking may
exceed 3 to 4 times body wt,
5-6 times bw while jogging,
and 8-9 times bw while
stumbling
Use law of cosines:
Hip Joint Muscles
• Uni-articular muscles
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–
–
–
Flexion - iliopsoas
Extension - gluteus maximus
Abduction - gluteus medius and minimus
Adduction - adductor brevis, longus, & magnus
• Biarticular muscles
– Hip flexion, knee flexion - sartorius
– Hip flexion,knee extension - rectus femoris
– Hip extension, knee flexion - hamstrings
• Note passive and active insufficiency of biarticular
muscles
Muscles of
Lower
Extremity:
Hip Jt
Muscle
Vectors:
Thigh
muscles
in
crosssection:
Physiological
crosssectional area
(PCSA) of
hip jt muscles
Why are lateral rotators
& gluteii muscles so large?
Common Injuries of the Hip
• Fractures
– Usually of femoral neck, a serious injury usually
occurring in elderly with osteoporosis
• Contusions
– Usually in anterior aspect of thigh, during contact
sports
• Strains
– Usually to hamstring during sprinting or overstriding
Knee Joint
• Ligaments and cartilage
– medial and lateral collateral ligaments
– anterior and posterior cruciate ligaments
– medial and lateral meniscus
• Muscles and movements
• Extensors
• quadriceps femoris (rectus femoris, vastus lateralis, vastus
medialis, vastus intermedius)
– Flexors
• hamstrings (semitendinosus, semimembranosus, biceps
femoris)
Knee Joint
Structure:
25% of Alpine skiing
injuries are ligament
injuries
Peripatellar pain
(runner’s knee)
caused by imbalance
of stress on patella
Lower Extremity
Misalignment:
Q angle is larger in females due to
Wider hip structure, increasing
potential for PFPS (Patellofemoral
pain syndrome)
Quadriceps Tendon
and Patella Force
Lines
Compressive force at PFJ is ½ body
wt during normal walking, and over
3 times bw during stair climbing
Comp force increases as knee flexion
Angle increases
Cruciate Ligaments
and Shear Stress
Loads on Knee
• Forces at tibiofemoral Joint
– Shear stress is greater during open kinetic chain exercises
such as knee extensions and knee flexions
– Compressive stress is greater during closed kinetic chain
exercises such as squats and weight bearing exercises.
• Forces at Patellofemoral Joint
– With a squat, reaction force is 7.6 times BW on this joint.
• Beneficial to rehab of cruciate ligament or patellofemoral
surgery
Thigh
muscles
in
crosssection:
PCSA of Muscles Crossing Knee
Common Injuries of the Knee
and Lower Leg
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Patellofemoral Pain Syndrome
Shin Splints
Anterior cruciate ligament (ACL) injuries
Posterior cruciate ligament (PCL) injuries
Medial collateral ligament (MCL) injuries
Meniscus Injuries
Iliotibial Band Friction Syndrome
Breaststroker’s Knee
Foot and Ankle joint structure
• Bones and arches of foot
• Tibia, fibula, calcaneus, talus, other tarsals,
metatarsals, phalanges
– Longitudinal arch, transverse arch
– plantar fascia
• Movements of ankle - talocrural joint
• Movements of foot - subtalar, intertarsal,
intermetatarsal, interphalangeal
Bones of Shank and Foot:
Ankle Joint Muscles and Movements
• Anterior compartment - All dorsiflex
– Tibialis anterior (also inverts)
– Extensor digitorum longus (also everts)
• Posterior compartment - All plantar flex
– Tibialis posterior (also inverts), gastrocnemius (also
flexes knee), & soleus
• Lateral compartment - All plantar flex & evert
– Peroneus longus & brevis
• Foot pronation and supination
Ankle and Foot Muscles:
Percent PCSA of Muscles Crossing Ankle
Subtalar Axis:
Foot Pronation and Tibial Torsion:
Rearfoot Movement During
Running:
Plantar Fascium
• What is the plantar fascium? - attaches to
calcaneus posteriorly and to the first row of
phalanges anteriorly
• What is its function?
– passive intertarsal stabilization
Arches
of the
Foot:
Plantar Fascium:
Plantar fascitis is 4th most
common cause of pain
among runners
(1st – knee pain, 2nd – shin
splints, 3rd- achilles tendonitis)
Plantar Fascitis – 4th leading cause of pain
in runners
• What causes plantar fascitis(inflamation of plantar fascium)?
– anatomic anomalies
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•
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microtears in fascium and bone spurs
inadequate flexibility of plantar flexors
inadequate strength of plantar flexors
functional pronation (eversion and abduction)
– overuse
•
•
•
•
overweight
poorly designed and poorly fitted shoes
running and jumping on hard surfaces
sudden increase in stress
• Treatment
– remove the cause(s)
– Therapeutic treatment to promote body’s natural healing
• NSAIDS
• Intermittent ice and heat
• Ultrasound, diathermy, massage
Patellar Chrondomalacia (a.k.a. Runner’s
Knee) – leading cause of pain in runners)
• Primary cause is imbalance in forces on patella
– Increased Q angle
– Pronated feet
• Tissues affected
– Degrading of articular cartilage of patella & femoral condyles
– Fluid collection, causing joint stiffness
• Symptoms
– Pain around patella with no particular injury causing it
– Worse going upstairs and downstairs, or after sitting awhile
– Feels like knee needs to be stretched
• Prevention/treatment
– Surgery is seldom beneficial
– Wet test – walk with wet feet on floor and determine if you have a hypermobile
foot. If so, purchase shoes and/or orthotics to decrease degree of foot pronation
– Exercises to increase strength/endurance of vastus medialis
Runner’s knee, cont’d
Wet test:
Safe exercise to develop vasti
muscles
Do not use knee sleeves!
Do not bend knee more than 20-30
degrees while doing extensions with
resistance!
Websites for Muscles, Movements, &
Problems of Lower Extremity
• Steadman-Hawkins Sports Medicine Clinic
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Shoulder joint impingement syndrome
Carpal tunnel syndrome
Patellofemoral pain syndrome
Lumbar disc herniation
Homework on lower extremity:
(Due Wed, Oct 20)
Introductory problems, p 263: 9,10
Additional problems, p 263-264: 6