Transcript Week 8 - Biomechanics of Human Lower Extremity

ENT 214
Biomechanics
Biomechanics of
Human Lower Extremity
Picture retrieved from
http://upload.wikimedia.org/wikipedia/commons/
d/d6/CT_3D_human_Foot_Skin_and_Bone.jpeg
Picture retrieved from
http://upload.wikimedia.org/wikipedia/en/f/f0/Tablum.jpg
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
Iliofemoral (Y)
ligament
Iliofemoral
ligament
Pubofemoral
ligament
Ischium
Ischiofemoral
ligament
Femur
Posterior view
Ischium
Femur
Anterior view
The integrity of the hip is enhanced by
the strong ligaments crossing the joint.
Structure of the Hip
Sacrum
Ilium
Acetabulum
Femoral
head
Pubis
Ischium
Femur
The pelvic girdle includes the two ilia and the
sacrum. It can be rotated forward, backward, and
laterally to optimize positioning of the hip.
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 from
http://en.wikipedia.org/wiki/Image:Sartorius.png
Picture retrieved from
http://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 from
http://en.wikipedia.org/wiki/Gluteus_maximus
Picture retrieved from
http://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 from
http://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
Femur
Patella
Tibia
Fibula
Bony structure of the tibiofemoral joint.
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
Lateral
meniscus
Transverse
ligament
Medial
meniscus
Posterior cruciate
ligament
Anterior cruciate
ligament
Superior view
The menisci of the knee.
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
Picture retrieved from
http://en.wikipedia.org/wiki/Image:Gray348.png
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 from
http://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 from
http://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 from
http://en.wikipedia.org/wiki/Image:Illu_lower_extremity_muscles.jpg
Structure of the Ankle
Fibula
Tibia
Talus
Calcaneus
Posterior view
The bony structure of the ankle.
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 from
http://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 from
http://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)
Picture retrieved from
http://en.wikipedia.org/wiki/Image:Foot.png
Structure of the Foot
Picture retrieved from
http://en.wikipedia.org/wiki/Image:Gray268.png
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 from
http://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
Plantar
Plantar
Arch
Fascia
Picture retrieved from
http://en.wikipedia.org/wiki/Plantar_arch
Picture retrieved from
http://en.wikipedia.org/wiki/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
Lateral view
Plantar fascia
Plantar view
The 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 from
http://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