Gait Analysis Flashcards
Difference between walking and running?
In walking, we always have a one foot on the ground. In running however there is a flight time where both feet are off the ground.
Stages of walking?
Initial contact (double support)—> opposite foot off (single support) —> opposite foot contact (double support) —> foot off—> (swing) initial contact
How is instability in having narrow base of support useful?
Having a narrow base of support and high centre of mass enables us to initiate movement by becoming unstable, secondary to small movements of the body.
Walk like a pendulum - bipedalism is nearly efficient!
How is flight triggered in terms of forces?
Flight occurs when centrifugal force exceeds gravitational force:
𝑣 > √(𝑔𝑟)
Diff in muscles and levers in bipeds and quadrupeds?
Levers are useless unless we have big muscles to keep them stiff.
In humans, we have large muscles surrounding the ankle and knee joints which helps us maintain our levers. Quadrupeds don’t have big muscles in the distal extremity because they don’t need to control a big lever near the floor.
Patellae give us a big lever arm at the knee so that we can support the body when we flex our knees. Horses don’t have patellae.
We need a big muscle (and a big lever arm) to keep the upper body erect. This is provided by the gluteus maximus. Chimps don’t have a well-developed butt so they can’t keep their bodies erect.
Why are our spines curved?
The curves of the spine tend to be more accentuated in the human subject.
Allows flexibility in the spine to adjust the position of our trunk in walking and standing
Without the lumbar curve we would be unstable because our trunk would point forward.
Together the thoracic and lumbar curve keep the centre of mass of the trunk above the pelvic girdle.
They need a flexible spine to accommodate their large heads.
Neurological control of movement?
The corticospinal tract provides the most direct pathway over which the cerebral cortex controls movement.
In rodents and marsupials this influence is exerted largely upon interneurons in the dorsal horn of the spinal grey matter.
However, in humans many axons terminate on the α motor neurones. Humans are believed to have more direct corticomotoneuronal synapses than any other species.
Movement in early development?
There is a caudal-rostral development of human movement in the infant. Head control, arm control, trunk control, proximal lower limb distal lower limb.
This is in contrast to many quadrupeds who come out ready to go!
Cortical and spinal circuits develop independently
At 2 years:
CST has innervated all the α-MNs (35 PCW)
CST has competed with afferents for terminations on the spinal neurones, reducing afferent input.
Efferent output from the α-MN pool greatly increased with sustained contractions.
Refinement spinal circuitry, ↑reciprocal inhibition Muscle mass increases with greater MYO:ECM
