Biomech Unit 3

Question 1

What are the parts of the hip joint?

Answer 1

Head of femur articulates with the acetabulum of the pelvis

Ball & socket joint

Question 2

What motion can be done by the hip joint?

Answer 2

Flexion + extension
Abduction + adduction
Internal + external rotation
Circumduction

Question 3

What provides intrinsic stability in the hip joint?

Answer 3

Tough fibrous tissue
Surrounding ligaments
Large, strong muscles
Ball & socket shape

Question 4

What is the ROM of the hip in different directions?

Answer 4

Flexion 140º, extension 20º
Abduction 30º, adduction 25º
External rot 90º, internal rot 70º

Question 5

What are the articulations of the knee joint?

Answer 5

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)

Question 6

What is the purpose of the menisci in the knee?

Answer 6

Make the tibial surface slightly concave to aid stability

Act as load distributers + shock absorbers

Question 7

What do the ACL/PCL bind to and where do they travel?

Answer 7

Femur to tibia

Pass through the intercondylar notch (between the 2 condyles of the femur)

Question 8

What type of bone is the patella?

Describe its shape

Answer 8

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)

Question 9

Where does the stability in the knee come from?

Answer 9

ACL + PCL (ant/post stability)
Medial/lateral collateral ligaments (med/lat stability)
Tough fibrous joint capsule
Quads muscle + menisci

Question 10

What sort of motion does the knee joint follow?

Answer 10

Screw home mechanism

follows a spiral motion - as it flexes, tib rotates internally; as it extends, tib rotates externally

Question 11

What is the ROM in the knee joint?

Answer 11

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

Question 12

What is the function of the patella?

Answer 12

To increase the lever arm of the quads muscle (to allow extension of the knee)

Question 13

What type of joint is the ankle?

And what are the articulations?

Answer 13

Hinged synovial joint 
Tibia, fibula + talus
- tibiotalar
-fibulotalar
- distal tibiofibular

Question 14

What provides stability to the ankle joint?

Answer 14

The arrangement of bones
Anterior inferior talofibular ligament
Medial ligament
Lateral ligament

Question 15

What is the ROM in the ankle?

Answer 15

Dorsiflexion 15º, plantar flexion 30º

Inversion 20º, eversion 5º

Question 16

What are the 3 parts of the foot and what bones are in each?

Answer 16

Hindfoot: talus + calcaneus
Midfoot: cuboid, medial, intermediate + lateral cuneiforms, navicular
Forefoot: metatarsals + phalanges

Question 17

Why is the foot so complex?

Answer 17

To adapt to varying ground surfaces,
To distribute loads + absorb shock,
Transmit loads from the ground to the rest of the body

Question 18

What is the subtalar joint?

Answer 18

Between the talus + calcaneus

Allows inversion/eversion of the foot

Question 19

What supports the arched structure of the foot?

How many longitudinal arches are there?

Answer 19

Plantar fascia

5 longitudinal arches (to each phalange)

Question 20

What is the purpose of the plantar fascia and how does it work?

Answer 20

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

Question 21

What is normal walking called?

Answer 21

Reciprocal gait

Question 22

What are the 2 main phases of walking?

Answer 22

Stance phase

Swing phase

Question 23

What are the phases of walking?

Answer 23

Heel contact
Flat foot
Mid stance
Heel off
Toe off
Mid swing
Heel contact

Question 24

What ROM is required at each joint for normal walking?

Answer 24

Hip: 15º ext, 30º flex
Knee: 70º flex, 1-2º ext
Ankle: 15º plantar, 10º dorsi

Question 25

What joint has the greatest ROM during normal walking/reciprocal gait?

Answer 25

Knee

Question 26

What causes the 2 peaks of force through the foot during normal walking?

Answer 26

1st: deceleration of body mass as weight transferred onto foot
2nd: pushing off the ground

(both greater than body mass)

Question 27

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)

Answer 27

• Hip extensors
• Hamstrings
• Quads
• Triceps surae (calf)