Biomechanics of Human Lower

Extremity

ENT 214 Biomechanics

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Structure of the Hip

What is the hip joint? a ball and socket joint where the head of the femur articulates with the concave acetabulum a more stable joint than the shoulder because of bone structure and the number and strength of the muscles and ligaments crossing the joint

Structure of the Hip

The integrity of the hip is enhanced by the strong ligaments crossing the joint.

Iliofemoral (Y) ligament

Pubofemoral ligament

FemurIschium

Anterior view

Femur

Iliofemoral ligament

Ischiofemoral ligament

Ischium

Posterior view

Structure of the Hip

The pelvic girdle includes the two ilia and the sacrum. It can be rotated forward, backward, and laterally to optimize positioning of the hip.

Femoral head

Femur

Acetabulum

Ilium

Sacrum

Pubis

Ischium

Movements at the Hip

What movements of the femur are facilitated by pelvic tilt?Pelvic tilt direction Femoral movement

posterior flexion

anterior extension

lateral (to opposite abduction

side)

Movements at the Hip

What muscles contribute to flexion at the hip?

iliacus psoas major assisted by:

pectineus rectus femoris sartorius tensor fascia latae

Picture retrieved fromhttp://en.wikipedia.org/wiki/Image:Sartorius.png

Picture retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/e/e2/Anterior_Hip_Muscles_2.PNG

Movements at the Hip

What muscles contribute to extension at the glenohumeral joint? gluteus maximus hamstrings

biceps femoris semimembranosus semitendinosus

Picture retrieved fromhttp://en.wikipedia.org/wiki/Gluteus_maximus

Picture retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/c/c6/Gluteus_maximus_muscle.PNG

Movements at the Hip

What muscles contribute to abduction at the glenohumeral joint?

• gluteus medius• assisted by:

• gluteus minimus

Movements at the Hip

What muscles contribute to adduction at the glenohumeral joint?

adductor magnus adductor longus adductor brevis assisted by:

gracilis

Picture retrieved fromhttp://en.wikipedia.org/wiki/Image:Anterior_Hip_Muscles_2.PNG

Structure of the Knee

What is the tibiofemoral joint? dual condyloid articulations between the medial and lateral condyles of the tibia and the femur; composing the main hinge joint of the knee

considered to be the knee joint

Structure of the Knee

Bony structure of the tibiofemoral joint.

PatellaTibia

Fibula

Femur

Structure of the Knee

What is the patellofemoral joint? articulation between the patella and the femur

the patella improves the mechanical advantage of the knee extensors by as much as 50%

Structure of the Knee

What are the menisci?

cartilaginous discs located between the tibial and femoral condyles

structures that distribute the load at the knee over a large surface area and also help absorb shock

Structure of the Knee

The menisci of the knee.

Lateral meniscus

Posterior cruciate ligament

Transverse ligament

Anterior cruciate ligament

Medial meniscus

Superior view

Structure of the Knee

What major ligaments cross the knee? collateral ligaments - cross the medial and lateral aspects of the knee

cruciate ligaments - cross each other in connecting the anterior and posterior aspects of the knee

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Movements at the Knee

What muscles contribute to flexion at the knee?

popliteus - “unlocks” the fully extended knee by laterally rotating the femur with respect to the tibia to allow flexion to proceed

Picture retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/c/c1/Gray439.png

Movements at the Knee

What muscles contribute to flexion at the knee? hamstrings assisted by:

gracilis sartorius popliteus gastrocnemius

Picture retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/d/dc/Gray1239.png

Movements at the Hip

What muscles contribute to extension at the hip?

quadriceps: rectus femoris vastus lateralis vastus medialis vastus intermedius

Picture retrieved fromhttp://en.wikipedia.org/wiki/Image:Illu_lower_extremity_muscles.jpg

Structure of the Ankle

The bony structure of the ankle.

Fibula

Tibia

Talus

Calcaneus

Posterior view

Structure of the Ankle

What is the tibiotalar joint?

hinge joint where the convex surface of the superior talus articulates with the concave surface of the distal tibia

considered to be the ankle joint

Structure of the Ankle

What is the distal tibiofibular joint?a syndesmosis where dense, fibrous tissue binds the distal tibia and fibula together

Picture retrieved fromhttp://en.wikipedia.org/wiki/Image:Ankle_en.svg

Movements at the Ankle

What muscles contribute to dorsiflexion at the ankle?

tibialis anterior extensor digitorum longus peroneus tertius assisted by:

extensor hallucis longus

Picture retrieved fromhttp://upload.wikimedia.org/wikipedia/commons/4/46/Peroneus_tertius.png

Movements at the Ankle

What muscles contribute to plantar flexion at the ankle? gastrocnemius soleus assisted by:tibialis posterior, plantaris, peroneus longus, flexor hallucis longus, peroneus brevis, flexor digitorum longus

Structure of the Foot

What is the subtalar joint?

the anterior and posterior facets of the talus articulate with the sustencalculum tali on the superior calcaneus)

Structure of the Foot

Picture retrieved fromhttp://en.wikipedia.org/wiki/Image:Foot.png

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Structure of the Foot

What are the tarsometatarsal and intermetatarsal joints?

nonaxial joints that permit only gliding movements enable the foot to function as a semirigid unit and to adapt flexibly to uneven surfaces during weight bearing

Picture retrieved fromhttp://en.wikipedia.org/wiki/Image:Gray358.png

Structure of the Foot

What are the metatarsophalangeal and interphalangeal joints? condyloid and hinge joints, respectively the toes function to smooth the weight shift to the opposite foot during walking and help maintain stability during weight bearing by pressing against the ground when necessary

Structure of the Foot

What are the plantar arches?

the medial and lateral longitudinal arches stretch form the calcaneus to the metatarsals and tarsals

the transverse arch is formed by the bases of the metatarsal bones

Picture retrieved fromhttp://en.wikipedia.org/wiki/Plantar_fascia

Picture retrieved fromhttp://en.wikipedia.org/wiki/Plantar_arch

Plantar

Arch

Plantar

Fascia

Structure of the Foot

What are the plantar fascia?

thick bands of fascia that cover the plantar aspects of the foot During weight bearing, mechanical energy is stored in the stretched ligaments,tendons, and plantar fascia of the foot. This energy is released to assist with push-off of the foot from the surface.

Structure of the Foot

The plantar fascia.

Lateral view

Plantar view

Plantar fascia

Movements of the Foot

What muscles are responsible for toe flexion and extension?

flexion - flexor digitorum longus, flexor digitorum brevis, quadratus plantae, lumbricals, interossei extension - extensor hallucis longus, extensor digitorum longus, extensor digitorum brevis

Picture retrieved fromhttp://en.wikipedia.org/wiki/Image:Gray442.png

Movements of the Foot

What muscles are responsible for inversion and eversion?

inversion - tibialis posterior, tibialis anterior eversion - peroneus longus, peroneus brevis, assisted by peroneus tertius