Musculoskeletal Flashcards
When one foot is midstance, what will the other one be?
Toe off.
For what proportion of the gait cycle is the foot on and off the ground?
Stance phase = 60%
Swing phase = 40%
What is the difference between a step and a stride?
A step is the distance between the heel strike of one foot and the heel strike of the other, a stride is the length between the heel strike of one foot and that foot’s next heel strike.
What is the difference between walking and running?
In walking you always keep one foot on the ground, in running there are periods where neither foot is on the ground.
What are synergistic muscles?
Muscles that facilitate the motion of an agonist muscle.
What is the difference between agonist and antagonist muscles?
Agonist muscles cause a movement by contracting, antagonist muscles oppose a movement.
What is the difference between concentric and eccentric muscle contraction?
Concentric = muscle shortens when it contracts Eccentric = muscle lengthens when it contracts
What is the difference between the action of ankle dorsiflexors and the action of ankle plantarflexors?
Ankle dorsiflexors make the toes point up, ankle plantarflexors make the toes point down.
What are the four stages of stance phase?
Heel strike- foot dorsiflexed, hip extensive contract, intrinsic foot muscles reserve arch
Flat foot - knee extensors make knee stiff, hip abductors stabilise pelvis, preserve longitudinal arch of foot with intrinsic muscles
Midstance
Propulsion - contract plantarflexors, hip abductors stabilise pelvis, intrinsic foot muscles preserve arch
What are the three stages of swing phase?
Toe off - eccentric contraction of hip flexors decelerates hip
Initial swing - concentric contraction of hip flexors accelerates mass, dorsiflexors clear foot of ground and prepare for heel strike
Terminal swing - hip extensors decelerate thigh, eccentric contraction of knee flexors decelerates leg, ankle dorsiflexed, knee extensors extend knee to place foot
What are 5 conditions that can alter the gait cycle?
Ageing - decrease in muscle bulk and flexibility reduces stride length so increases number of steps
Structural damage to nerves, blood supply, tendons, bones
Arthritis, and other inflammatory and degenerative conditions
Neurological conditions e.g Parkinson’s
Footwear
What do you call the gait where it hurts to weight bear on the affected limb so the stance phase is reduced?
Antalgic gait
What do you call the gait that is unsteady and uncoordinated, so there is a wide base with feet thrown out and the trunk may sway?
Cerebellar/ataxic gait
What do you call the shuffling gait with short steps and trunk flexed forward?
Parkinsonian
What do you call the gait where the hip abductors are weakened so the pelvis drops to the side of the non weight bearing leg, like a waddle?
Myopathic/Trendelenburg gait
What do you call the gait where the ankle dorsiflexors are weak so the limb has to be lifted higher for the foot to clear the ground?
Neuropathic/ high-stepping gait
What is moment/torque?
The perpendicular distance between a joint and the muscles line of action.
What should the lengths of the inlever and outlever be when you want strength and when you want speed?
If you want strength of force, you need a relatively long inlever and relatively short outlever.
If you want speed you need a relatively short inlever and relatively long outlever.
What is the normal human gait cycle?
The period from heel strike of one limb to the next time that heel hits the ground.
Where is the CoM in humans standing upright?
In the midline of the pelvis, anterior to S2.
Which muscle groups allow us to sway slightly forwards and backwards to keep our CoM inside our base of support and ourselves balanced?
Plantarflexors if the CoM has moved just anterior to base of support.
Dorsiflexors if the CoM has moved just posterior to the base of support.
What 5 adaptations do humans have for efficient bipedalism?
1) Iliofemoral ligament twisted around the head of the femur which prevents backward movement, allows flexion but prevents extension
2) Cervical, thoracic and lumbar curvatures of spine, so weight borne by spine s over the base of support and cancelled out
3) Human pelvis is wider, shorter and has more antero-posteriorly orientated ilium than chimpanzee
4) Sacroiliac joint is closer to acetabulum (because ilium is wider than it is tall) so weight is transferred from spinal column to hip joint without putting too much stress on ilium
5) Chimpanzees only have extensors because the muscles only at the back, humans have hip abductors as well as extensors so the Trendelenburg gait is prevented
Weakness in which muscles causes Trandelenburg gait?
Gluteus medius and gluteus minimis muscles. Gait causes a lot of energy expenditure.
What is the difference between the human femur and chimpanzee femur?
The human femur has a larger head because each bone bears more weight.
The human femur is angled inwards (bicondylar angle) so when one leg is lifted the base of support is still directly below the trunk.