TEC1 - Semester 2: Lower Extremity Flashcards
What are the functions of the LE?
- locomotion
- carry weight of entire erect body
- subject to exceptional forces
What are the components of the LE?
femur, patella, tibia & fibula, bones of foot
Describe the femur.
- largest, longest and strongest bone
- larger Q-angle in women
- articulates with acetabulum, tibia and patella
Describe the patella.
- sesamoid bone; contained within patellar ligament
- improves leverage of thigh muscles
- articulates with femur
Describe the tibia.
- receives body weight from femur and transmits it to foot
- articulates with femur, fibula (proximally and distally), interosseous membrane
Describe the fibula.
- NOT weight bearing
- increases surface for muscle attachment
- stabilizes ankle joint
- articulates with tibia, lateral talus and interosseous membrane
Describe the hip joint.
- between femur and acetabulum
- ball and socket joint
- multiaxial synovial, diarthrodial
- good ROM
Describe the knee joint (femur + tibia)
- modified hinge joint
- biaxial synovial, diarthrodial
Describe the knee joint (femur + patella)
- plane joint
- uniaxial synovial, diarthrodial
Describe the proximal tibia + fibula joint.
- plane gliding
- synovial, diarthrodial
Describe the distal tibia + fibula joint.
- fibrous
- synarthrotic
Describe the ankle joint.
- between tibia, fibula, talus
- hinge
- uniaxial synovial, diarthrodial
What does the joint stability in the lower limb depend on?
- stability in hip, knee and ankle joints
- stability of dynamic structures (muscle, tendon, fascia): ability to adjust length in response to demands
- integrity of ligaments in flexion and extension
What is the Angle of Inclination?
angle between long axis of neck of femur and shaft in frontal plane
Where is the normal angle of inclination?
115-140 degrees. usually less in women
What is Coxa Vara?
when angle is less than 115 degrees
What does coxa vara result in?
- shortening of limb
- reduction of load on femoral head
- load on femoral neck increased
Causes for coxa vara?
trauma, congenital, Paget’s disease, Perthe’s disease, osteomyelitis, osteogenesis imperfecta, tumors
What is coxa valga?
when angle is greater than 140 degrees
What does coxa valga result in?
- lengthening of limb
- reduction of load on femoral neck
- load on femoral head is increased
Causes for Coxa Valga?
skeletal disease, spasticity, cerebral palsy, spinal dystrophism, poliomyelitis
What is the angle of torsion?
angle of femoral neck in the transverse planew
what is the normal angle of torsion?
12-15 degrees
What is anteversion?
angle of torsion is >15 degrees
What happens to the femur in anteversion?
internal rotation of femur -> toes face inward
What is retroversion?
angle of torsion is <15 degrees
What happens to the femur in retroversion?
external rotation of femur -> toes out
Name the hip ligaments.
iliofemoral, pubofemoral, ischiofemoral, ligamentum teres
Describe the iliofemoral ligament.
- one of the strongest in the body
- anterior
- v-shaped
Describe the pubofemoral ligament.
- medial inferior
- blends with iliofemoral
- limits abduction and external hip rotation
Describe the ischiofemoral ligament.
- posterior
- spirals around to ant greater trochanter
- limits internal rotation
Describe the ligamentum teres.
- intracapsular lig
- attaches head of femur to floor of acetabulum
- contains an artery
Which function do all four ligs perform?
limit extension of the hip
Where is the COG and how is the weight distributed in bilateral limb stance?
COG: between the two hips, equal force exerted on both hips
weight: body weight minus that of the legs is supported equally on femoral heads
What happens in single leg stance?
- COG moves distally and away from the supporting leg
- non-supporting leg becomes a part of the body mass and acts upon weight-bearing hip
- stance leg abductors offset the change in COG
What does the knee joint do?
flexion and extension in sagittal plane, small rotational component in transverse plane
Which muscle tendons reinforce the capusle?
quadriceps, semimembranosus
What is the Q angle?
angle formed between the quadriceps muscles and the patella tendon
What is the normal Q angle in males and females?
m: 10-14
f: 15-17
What is genu valgum & varus?
genu valgum: >20
genu varus: <10
Name the ligaments of the knee.
medial & collateral ligaments, ACL, PCL, ligamentum patallae
What do the medial & lateral collateral ligaments do?
protect against valgus strain
Which function do all ligaments perform?
prevent excessive extension
What is the Pes Anserine of the knee?
insertion of the sartorius, gracilis and semitendinosus muscles
Describe the ACL and PCL.
ACL: protects against anterior shear forces. Taut during extension.
PCL: protects against posterior
shear forces. Taut during Flexion
What are functions of the menisci?
- shock absorption
- increase congruency between condyles of femur and those of tibia
- moves synovial fluid through joint
What happens in the locking mechanism of the knee?
femoral condyles roll on tibial condyles mostly in sagittal plane. in the last few degrees of extension, it slightly rotates in transverse plane to lock the knee
How does the locking mechanism effect the tibia and the ACL?
tibia: rotates laterally
ACL: becomes taut -> also causes external rotation of tibia
How is the knee unlocked?
by contraction of popliteus -> femur rotates laterally and tibia medially
What are the functions of the patella?
- reduce tendon/ligament strain
- spread forces to condyles
- increase force of quadriceps
What are the ligaments of the prox. tibiofibular joints?
Anterior & Posterior Tib-Fib, Lat collateral ligament
What are the main joints of the foot and ankle?
- ankle: tibia/fibula and talus
- intertarsal and tarsal-metatarsal
- metatarsal-phalangeal
-interphalangeal
Describe the ankle joint.
Hinge, uniaxial, synovial, diarthrodial
Describe the intertarsal & tarsal-metatarsal joints.
- Plane, ball and socket, condyloid
- Synovial, diarthrodial
Describe the metatarsal-phalangeal joints.
Condyloid, synovial, diarthrodial
Describe the interphalangeal joints.
Hinge, uniaxial, synovial, diarthrodial
What are the functions of the foot and ankle?
- support of body weight
- lever to propel body forward
- shock absorber
What are distal tib-fib ligaments?
inf. ant. & post. tib-fib, transverse tib-fib ligaments
Other joints of ankle and foot?
> talo-crural
subtalar
talo-calcaneal-navicular
calcaneo-cuboid
Describe the talo-crural joint.
- synovial, uniaxial, hinge
- between sup. talus and inf. surface of medial malleolus (of tibia)
- between lat. talus and med. surface of lateral malleolus (of fibula)
Lateral collateral Talo-crural ligaments?
Anterior & posterior talofibular ligament, calcaneofibular ligament
What is their function?
resist inversion of ankle
Medial collateral talo-crural ligaments?
Anterior & Posterior tibiotalar lig., tibiocalcaneal and tibionavicular
What is their function?
resist eversion of ankle
Which movements does the joint allow?
plantarflexion and dorsiflexion
Describe the subtalar joint.
- synovial condyloid
- between ant, post and middle facets of talus and facets on calcaneus
Ligaments of that joint?
interosseous, lateral, medial, posterior and anterior talo-calcaneal
What is their function?
stabilize against excessive movements
Which movements does the joint allow?
pronation and supination -> movement in all three axes
Describe the talo-calcaneo-navicular joint
- synovial, multi-axial, tri-planar ball and socket joint
- between distal head of talus, prox. surface of navicular and plantal calcaneonavicular ligament
Which movements does the joint allow?
pronation/ supination, inversion/eversion
Ligaments of the joint?
- talonavicular, interosseous talocalcaneal and plantar calcaneonavicular ligament
Describe the calcaneocuboid joint.
- between distal surface of calcaneus and prox. surface of cuboid
- least mobile joint in the body
Why is the plantar calcaneonavicular ligament (=spring ligament) so important?
is a static restraint of medial longitudinal arch. supports head of talus from plantar and medial subluxation when standing
Describe the interphalangeal joints.
- synovial hinge joints
- flexion and extension
Describe the metatarsophalangeal joints.
- condyloid joints
- permit flexion, extension, adduction, abduction
Describe the intermetatarsal joints.
- plane gliding joints