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
• Self-study problems (keep to prepare for exam)
Hip: Front
View
Normal hip jt ROM:
Abduction 45 deg
Adduction 20 deg
Flexion 120 deg
Hyperext 30 deg
Internal rot 35 deg
External rot 30 deg
Loads on the Hip
• During stance phase of walking:
– Compression forces on hip is greater than body weight
(due to muscle tension)
• Increases with hard-soled shoes
• Increases with gait increases (both support and
swing phase)
• 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
Muscles of
Lower
Extremity:
• Uni-articular muscles
–
–
–
–
Hip Joint
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
Hip Jt
Muscle
Vectors:
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
Structure:
25% of Alpine skiing
injuries are ligament
injuries
Peripatellar pain
(runner’s knee)
caused by imbalance
of stress on patella
Normal knee jt ROM:
Flexion 140 deg
Hyperext 0 deg
Rot (knee bent 30 deg)
Internal 30 deg
External 45 deg
Knee Ligaments and cartilage
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
Calculating patellar compressive
Force using law of cosines. Prob
10, p 263
Quadriceps-patella and anterior
shear force
Knee loading summary
• 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.
– Increases as knee is flexed
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)
Thigh
muscles
in
crosssection:
PCSA of Muscles Crossing Knee
Common Injuries of the Knee
and Lower Leg
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ACL injuries
PCL injuries
MCL injuries
Prophylactic Knee Bracing
Meniscus Injuries
Patellofemoral Pain Syndrome
Shin Splints
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 Normal ROM
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•
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Plantar Flexion 50 deg
Dorsiflexion 15-20 deg
Inversion 20-30 deg
Eversion 5-15 deg
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:
Patellar Chondromalacia (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!
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
• Website for plantar fascitis (Click on “view
eorthopod”, then “foot”, then “plantar
fascitis”)
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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microtears in fascium and bone spurs
inadequate flexibility of plantar flexors
inadequate strength of plantar flexors
functional pronation (eversion and abduction)
– overuse
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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
• Website for patellofemoral problems disorders
(Click on “view eorthopod”, then “knee”, then
“patellofemoral problems”)
Problems on lower extremity:
(Keep to prepare for exam)
Introductory problems, p 263: 9,10
Additional problems, p 263-264: 6