Gait and Posture Flashcards
What is meant by “gait and posture”?
What kind of activities could be involved?
gait and posture refers to all activities that we do that transfer the weight of our body and move us in a certain direction
- going from sitting to standing
- standing still
- walking
- running
- jumping
- climbing steps
- rowing
- cycling
What is bipedalism?
the way in which humans walk using two legs, rather than 4
Why do toddlers tend to crawl before learning how to walk?
not all babies crawl before walking
muscle mass has not developed enough
toddlers are going through a rapid change in brain development and they do not have the coordination / balance yet to be able to walk on 2 legs
when babies start to stand, they tend to hold onto things and pull themselves up to stand and balance
What is shown in this image and what does it suggest?
“Lucy” - a skeleton found showing a very small / short figure
but had the anatomy of a biped - broad pelvis and femurs angled towards the midline
When did hominids start to grow taller?
Why did this happen?
the first hominids could walk upright but still have features of a more primitive species - short legs and long arms
1.9 million years ago hominids grew taller, with longer legs
there are many theories about why we move on 2 feet, but no definitive answer
e.g. change of environment made being bipedal more advantageous
What is gait?
how we translocate the centre of body mass in the direction of locomotion
joint motion, muscle activity and load bearing of limbs is generally symmetrical
gait is a cyclic activity with each cycle lasting about 1 second
Why do we study gait?
physicians need sound knowledge of normal gait so they can accurately detect and interpret deviations from normal gait pattern
it is important to note that each individual displays certain variations from the norm, which are superimposed on the normal pattern of walking
Is everyone’s gait the same?
everybody has their own characterisitc pattern:
- stride length
- pelvic movement
- upper body position
What factors affect gait in normal people?
- height
- weight
- build
- clothing
- shoes
- weight carriage
- age
What is meant by “weight carriage” affecting gait?
someone being heavier can affect their gait in different ways
an overweight person tends to walk with wider gait
in pregnancy, the weight is not evenly distributed around the body so this will affect their gait differently
How does alcohol affect gait?
alcohol affects the cerebellum, which is important for balance and posture
posture / gait becomes abnormal and unsteady when the cerebellum is affected by alcohol
the cerebellum can become atrophied if someone abuses alcohol over a long period of time
patients with an alcohol problem have an irreversible change in their gait - tend to have a wider base & difficulty with balance
What 4 factors does normal gait rely on?
Joints:
- intact bones & well functioning joints
Muscles:
- adequate muscle strength to support joints / bodyweight
Nerves:
- CNS & PNS supply the muscles
Vision:
- including vestibular and auditory systems
What is the importance of vision in ensuring normal gait?
provides information about the movement of the head and body relative to the surroundings
it is important for the automatic balance responses to changes in surface conditions
once visual cues are taken away, gait changes and people do not move as fluidly or quickly as they are thinking about potential danger
What are the stages involved in learning to walk?
By what age is this usually complete?
- sitting without support
- standing with assistance
- hands and knees crawling
- walking with assitance
- standing alone
- walking alone
the time frame is very variable but most babies are walking by 18 months
they tend to start by pulling themselves up using furniture and using this to balance as they pull themselves along
What are the main factors influencing gait changes in the elderly?
- decreased muscle bulk
- decreased strength and flexibility
- some loss of hearing and vision
Why is it important to encourage elderly people to stay active?
from age 35, people start to lose muscle mass
muscle atrophy is present in the elderly, affecting their gait, even if they do not have any pathology
encouraging the elderly to stay active and maintain the muscle mass reduces the risk of falls
What are the gait changes that can be seen in the elderly?
major changes:
- reduction in velocity
- reduction in step / stride length
minor changes:
- decreased arm swing
- decreased rotation of the pelvis
to increase velocity, the elderly tend to take more steps instead of increasing stride length
Where is the centre of gravity of the body?
centre of gravity is just anterior to S2 vertebra
it is slightly posterior to the hips
it is anterior to the knee and ankle
muscles in the leg need to be active during standing to maintain the centre of gravity and keep us upright
What is the consequence of the centre of gravity passing anterior to the ankle joint?
How is this counteracted?
this leads to a tendency to fall forwards - “forward sway”
this is counteracted by contraction of the plantar flexors
particularly soleus, but also gastrocnemius
the plantar flexors are the muscles which would point the toes towards the floor
What are the 2 phases of the gait cycle?
stance phase:
- makes up 60% of the gait cycle
- the foot is in contact with the ground
swing phase:
- makes up 40% of the gait cycle
- the foot is in the air
the start and end of the stance phase is marked by a short period of double support (10%) in which both feet are on the ground
What are the 7 stages involved in the gait cycle?
- heel strike (initial contact)
- loading response (foot flat)
- midstance
- terminal stance (heel off)
- preswing (toe off)
- initial and midswing
- terminal swing
What is a dynamic muscle contraction and the two types?
a muscle contraction in which there is a change in length
concentric contraction:
- muscle shortens while contracting
eccentric contraction:
- muscle lengthens while contracting
What is an isometric muscle contraction?
a muscle contraction in which there is no change in length
When does the heel strike phase begin?
Which muscles are involved in this phase?
- begins when heel strikes the ground
- lowering of forefoot to the ground is controlled by eccentric contraction of tibialis anterior
- deceleration of forward momentum acheived by hip extension by gluteus maximus
- ankle and subtalar joints accommodate terrain
What is the loading response?
Which muscles are involved in this phase?
- the foot comes into full contact with the ground
- bodyweight is transferred to stance limb
- knee extension by quadriceps femoris prevents the knee from buckling under the weight
What happens during the mid-stance phase?
Which muscles are involved in this phase?
- the opposite limb swings past the stance limb
- it requires stabilisation of the pelvis to keep it level
- this is acheived by abduction of the hip by gluteus medius and gluteus minimus
- these muscles contract and pull the pelvis to keep it level and stop it swaying to the opposite side when the foot is taken off the ground
What happens during the terminal stance phase?
Which muscles are involved?
- the heel starts to lift off of the ground
- this is achieved by the plantar flexors - soleus & gastrocnemius
- this also accelerates mass forwards and pushes us forwards
What is involved in the pre-swing (toe-off) phase?
Which muscles are involved?
- final stage of the stance phase in preparation for moving into swing phase
- powerful plantarflexion of digits to push off from the ground and accelerate mass forwards (mainly big toe)
- preparation for hip flexion by eccentric contraction of rectus femoris
Which digit / muscles are essential for toe-off?
hallux is essential for toe-off
it is stabilised by adductor hallucis and abductor hallucis brevis
misaligned or missing hallux can cause problems
What happens during the initial and mid-swing phases?
Which muscles are involved?
- hip flexion carries the limb forwards - iliopsoas and rectus femoris
- tibialis anterior leads to dorsiflexion of the toe and foot to allow the foot to clear the ground
- knee flexion occurs to shorten the limb - hamstrings
What is involved in the terminal swing phase?
What muscles are involved?
- quadriceps ensures knee flexion is greater than extension to place the foot in the correct position ready for heel-strike
- this is assisted by dorsiflexion of ankle - tibialis anterior
- eccentric contraction of hamstrings decelerates limb in preparation for heel-strike
- end of swing phase signifies 1 complete gait cycle of one lower limb
What is the solution when limited knee flexion means that the limb can’t be shortened?
limb circumduction
the swinging leg moves in an arc rather than straight forwards
this increases the ground clearance of the swing foot
What is the problem associated with foot-drop?
Which nerve is injured and how does the person compensate?
the foot cannot be dorsiflexed
there is initial toe/forefoot contact with the ground rather than the heel meaning there is no push off
injury to the deep fibular nerve
this supplies the anterior compartment muscles which dorsiflex the ankle and foot so that the toes do not touch the ground
Why is it important for the body’s centre of gravity to be fairly constant?
it minimises energy expenditure so that walking is extremely energy efficient
as you walk, the action of the muscles limits the vertical rise (up and down) of the pelvis and the lateral shift
How does pelvic drop affect the centre of gravity?
Which muscles control this and what type of gait does this lead to?
pelvic drop to the swing side minimises rise in centre of gravity
abduction on stance side controls and limits the drop - abductor muscles maintain pelvic stability
pelvic drop leads to Trendelenberg gait, which is seen in:
- stroke
- hip osteoarthritis
- cerebral palsy
- superior gluteal nerve damage
What is the role of the hip adductors in maintaining centre of gravity?
hip adduction minimises lateral shift in C of G
adductors pull the knees towards the midline to limit lateral shift in centre of gravity during walking
this prevents broad gait when walking and makes it more streamlined, as we walk with one foot in front of the other
