ch08- the biomechanics of the upper extremities

8/7/2019 ch08- The Biomechanics of the Upper Extremities

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Chapter 8:The Biomechanics of the

Upper ExtremitiesBasic Biomechanics, 4th edition

Susan J. Hall

Presentation Created by

TK Koesterer, Ph.D., ATC

Humboldt State University


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Objectives Explain how anatomical structure affects movement

capabilities of lower extremity articulations.

Identify factors influencing the relative mobility andstability 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 lowerextremity movements.

Describe the biomechanical contributions to common

injuries of the lower extremity.


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Structure of the Hip

Anterior reinforcement from iliofemoral

ligament and pubofemoral ligament

Posterior reinforcement from ischiofemoralligament.

Iliopsoas Bursa

Deep Trochanteric Bursa Femur major weightbearing bone

Longest, largest and strongest in body.


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Movements at the Hip

Pelvic Girdle

Flexion

Extension

Abduction

Adduction

Medial and Lateral Rotation of Femur Horizontal Abduction and Adduction


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Loads on the Hip During swing phase of walking:

Compression on hip approx. same as body

weight (due to muscle tension) Increases with hard-soled shoes

Increases with gait increases (both supportand swing phase)

Body weight, impact forces translated upwardthru skeleton from feet and muscle tensioncontribute to compressive load on hip.


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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


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Structure of the Knee

A large synovial joint with three articulations

within joint capsule.

Tibiofemoral Joint

Menisci

Ligaments: tibial and fibular collateral,

anterior and posterior cruciate, iliotibial band Patellofemoral Joint

Joint Capsule and Bursae


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Movements at the Knee

Flexion and Extension

Popliteus

Quadriceps

Rotation and Passive Abduction and

Adduction

Patellofemoral JointMotion


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Loads on Knee Forces at tibiofemoral Joint

Loaded with shear and compression forces

during daily activities.Medial tibial plateau

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


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Common Injuries of the Knee

and Lower Leg ACL injuries

PCL injuries

MCL injuries Prophylactic Knee Bracing

Meniscus Injuries

Iliotibial Band Friction Syndrome

Breaststrokers Knee

Patellofemoral Pain Syndrome

Shin Splints


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Structure of the Ankle

Movements of the ankle:

Dorsiflexion

Tibialis anterior

Extensor digitorum longus

Peroneus tertius

Plantar Flexion: Two heads of gastrocnemius

Soleus


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Structure of the Foot

Subtalar Joint

Tarsometatarsal and Intermetatarsal Joints

Metatarsophalangeal and interphalangeal

Joints

Plantar Arches


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Muscles of the Foot

Extrinsic muscles cross ankle

Intrinsic muscles have both attachments

within the foot.

Toe Flexion and Extension

Inversion and Eversion

Pronation and Supination


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Loads on the Foot Structures of foot anatomically linked to

evenly distribute load over whole foot.

50% of BW distributed through subtalarjointto calcaneous

Remaining 50% transmitted acrossmetatarsal heads.

Architecture of food affects loading Flat arch: reduced forefoot load

High arch: increased forefoot load


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Common Injuries of the Ankle

and Foot Ankle Sprains

Inversion sprain much more common than

eversion sprains

Overuse Injuries

Tendonitis Excessive pronation

Stress Fractures


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Common Injuries of the Ankle

and Foot Alignment Anomalies of Foot:

Varus

Valgus

Injuries Related to High and Low Arch

Structures


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Summary

Lower extremity well adapted to function ofweight bearing and locomotion

The hip is a typical ball and socket joint The knee is a large, complex joint composed

of two side-by-side condyloid articulations

The ankle includes articulations of the tibia

and fibula with the talus. Like the hand, the foot is composed of many

small bone their articulations

ch08- the biomechanics of the upper extremities

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