musculoskeletal system - standing/gait cycle (lecture 11)

Question 1

discuss importance of musculoskeletal structure for bipedal standing in comparison to quadrupedal standing

Answer 1

• humans are energy efficient due to their ability to lock their joints (hip and knee) in accordance with their line of gravity
• quadrupedal standing requires muscles and limbs to be active at joints, therefore energy demanding
• slow muscle fibres allow humans to withstand fatigue in our larger muscles

Question 2

relate muscle roles to actions

Answer 2

agonists act concentrically
antagonists act eccentrically
stabilisers act isometrically
& gravity can act as an antagonist or agonist

Question 3

explain how the line of gravity falls in the lower limb of the human body

Answer 3

our line of gravity…
sits posterior to the hip
anterior to the knee
anterior to the ankle
this pushes the hip and knee into a locked state of extension where the ligaments are tight and no energy is being spent
the ankle does NOT lock, plantarflexors must stabilise

Question 4

name the 6 key parts to the gait cycle

Answer 4

early stance (heel strike)
mid stance
late stance (toe off)
early swing
mid swing
late swing

Question 5

explain early stance ( heel strike)

Answer 5

hip - in flexion, moving to extension
knee - in extension for contact with ground (locked)
ankle - in dorsi, slowly moving to plantar (ta)
body - behind leg ready to move in line

Question 6

explain mid stance

Answer 6

hip - continuing moving into extension
knee - from extension to slight flexion
ankle - continuing to move into plantar (ta)
body - moving in line and and slightly past leg

Answer 7

hip - reaches max extension and ready to flex
knee - in extension due to body and hip moves to flexion with ankle to toe off ready for swing
ankle - from full planter to toe off
body - continuing to move max past leg

Question 8

explain early swing

Answer 8

hip - moving into flexion
knee - MUST move into flexion to clear foot from ground
ankle - MUST dorsiflex to clear ground
leg - max behind body, begin to catch up to body

Question 9

explain mid swing

Answer 9

least amount of change here
hip - remains in flexion but slightly more
knee - remains in flexion but slightly more
ankle - remains in dorsi, ready for heel strike
leg - swinging under body, moving from slightly behind to slightly in front

Question 10

explain late swing

Answer 10

hip - in flexion ready for heel strike
knee - moves from flexion to extension ready for heel strike
ankle - remains in dorsi (as in air) ready to heel strike stabilised by triceps surae
leg - moves to max in front of body while in air ready to heel strike