Biomech Unit 3 Flashcards
What are the parts of the hip joint?
Head of femur articulates with the acetabulum of the pelvis
Ball & socket joint
What motion can be done by the hip joint?
Flexion + extension
Abduction + adduction
Internal + external rotation
Circumduction
What provides intrinsic stability in the hip joint?
Tough fibrous tissue
Surrounding ligaments
Large, strong muscles
Ball & socket shape
What is the ROM of the hip in different directions?
Flexion 140º, extension 20º
Abduction 30º, adduction 25º
External rot 90º, internal rot 70º
What are the articulations of the knee joint?
Tibiofemoral (proximal tib + distal femur)
Patellofemoral (patella + distal femur)
(fibula does not form part of the knee joint, but does act as an anchor for the biceps femurs + LCL)
What is the purpose of the menisci in the knee?
Make the tibial surface slightly concave to aid stability
Act as load distributers + shock absorbers
What do the ACL/PCL bind to and where do they travel?
Femur to tibia
Pass through the intercondylar notch (between the 2 condyles of the femur)
What type of bone is the patella?
Describe its shape
Sesamoid bone (bone found in a tendon) in the quads tendon
2 smooth surfaces that articulate with the condyles + a ridge that guides the patella down the groove (when flexing/extending)
Where does the stability in the knee come from?
ACL + PCL (ant/post stability)
Medial/lateral collateral ligaments (med/lat stability)
Tough fibrous joint capsule
Quads muscle + menisci
What sort of motion does the knee joint follow?
Screw home mechanism
follows a spiral motion - as it flexes, tib rotates internally; as it extends, tib rotates externally
What is the ROM in the knee joint?
Flexion 140º, extension 1-2º Ab/adduction = a few degrees Internal/exteneral: - none at full extension - at 90º ext rot 45º, int rot 30º - decreases after 90º
What is the function of the patella?
To increase the lever arm of the quads muscle (to allow extension of the knee)
What type of joint is the ankle?
And what are the articulations?
Hinged synovial joint Tibia, fibula + talus - tibiotalar -fibulotalar - distal tibiofibular
What provides stability to the ankle joint?
The arrangement of bones
Anterior inferior talofibular ligament
Medial ligament
Lateral ligament
What is the ROM in the ankle?
Dorsiflexion 15º, plantar flexion 30º
Inversion 20º, eversion 5º
What are the 3 parts of the foot and what bones are in each?
Hindfoot: talus + calcaneus
Midfoot: cuboid, medial, intermediate + lateral cuneiforms, navicular
Forefoot: metatarsals + phalanges
Why is the foot so complex?
To adapt to varying ground surfaces,
To distribute loads + absorb shock,
Transmit loads from the ground to the rest of the body
What is the subtalar joint?
Between the talus + calcaneus
Allows inversion/eversion of the foot
What supports the arched structure of the foot?
How many longitudinal arches are there?
Plantar fascia
5 longitudinal arches (to each phalange)
What is the purpose of the plantar fascia and how does it work?
Acts as a shock absorbed to prevent collapse of the longitudinal arches when loaded
Forms a cable from the heel to toes so prevents collapse,
When the toes are dorsiflexed the fascia is stretched which shortens the foot + causes arch to rise
What is normal walking called?
Reciprocal gait
What are the 2 main phases of walking?
Stance phase
Swing phase
What are the phases of walking?
Heel contact Flat foot Mid stance Heel off Toe off Mid swing Heel contact
What ROM is required at each joint for normal walking?
Hip: 15º ext, 30º flex
Knee: 70º flex, 1-2º ext
Ankle: 15º plantar, 10º dorsi
What joint has the greatest ROM during normal walking/reciprocal gait?
Knee
What causes the 2 peaks of force through the foot during normal walking?
1st: deceleration of body mass as weight transferred onto foot
2nd: pushing off the ground
(both greater than body mass)
What muscles contract to;
- prevent body falling forwards at heel contact
- prevent knee hyperextension after heel contact
- prevent the knee buckling
- toe off (cause plantar flexion)
- Hip extensors
- Hamstrings
- Quads
- Triceps surae (calf)
