Lecture 8 - Biomechanics

Question 1

Define biomechanics?

Answer 1

• Application of mechanical laws to human body

* Includes: muscle action, joint movements, bone structure, GRF & axes of motion

Question 2

Functions of the Foot?

Answer 2

1. Shock absorption, adapt uneven surfaces
2. Transverse rotation absorber (in gait)
3. Propulsion (rigid to push off)
4. ‘Loose bag of bones’ to Rigid leaver

Question 3

Define Compensation

Answer 3

change of structure/position/function of one part of the body to adjust to a deviation of structure/position/ function of another part

Question 4

Define Hypermobility

Answer 4

movement of segment part that should be fixed/stable when stress applied

Question 5

Define Subluxation

Answer 5

separation of joint

pronation= subluxation talo-navicular joint

Question 6

Define Pathomechanics

Answer 6

Abnormal functioning/ movement of body part

Question 7

Motions of foot occur in Saggital plane?

Answer 7

dorsiflexion/ plantarflexion

Question 8

Motions of the foot occur in Transverse plane?

Answer 8

Adduction
[adduction, plantarflexion & inversion]
Abduction
[abduction, dorsiflexion & eversion]

Question 9

Motions occuring in frontal plane?

Answer 9

Inversion/ Eversion

Question 10

Tri planar motion?

Answer 10

Supination/ Pronation

Question 11

Where is the STJ Axis located?

Answer 11

16° from SP & 42° from TP

Question 12

List forces acting on foot

Answer 12

1.Ground reaction force 
(contact & propulsion)
2.Linear sheer 
(netball stopping & starting quickly)
3.Torque (associated with limb rotations)
4.Lateral sheer (side to side) 
= callus, blister

Question 13

List Root’s ‘normal’ stance criteria

Answer 13

1. Vertical calcaneus & tibia
2. STJ neutral
3. MTJ axes (talonavicular & calcaneocuboid joints) locked in their pronated positions
4. All metatarsals touching ground & forefoot parallel to rear foot
5. No muscle support to maintain foot structure
6. Gastrocnemius contraction exerts nearly continual plantarflexory force at AJ & loads forefoot