Presentation on theme: "Normal human gait: Ankle motion: Ankle is? Talus is the last bone of the vertical weight bearing system, weight is then transferred forwards and backwards."— Presentation transcript:
Normal human gait: Ankle motion: Ankle is? Talus is the last bone of the vertical weight bearing system, weight is then transferred forwards and backwards. Motion of the ankle: What is dorsiflexion? Plantar flexion? Reference? During the gait cycle: two arcs of plantar flexion and two arcs of dorsiflexion. 1 st arc of motion: PF 8 – 10 degrees. (what does this motion represent??)
2 nd arc: DF from 10 of PF to 10 of DF: which part move on which? What does this motion represent? 3 rd arc: PF from 10 of DF to 20 degrees of PF (rapid motion). 4 th arc: DF from 20 degrees of PF to neutral which is usually reached in mid-swing (motion starts after toe-off). GRFV: GRFV passes from posterior to ankle to anterior to it during stance, what happens during swing?
GRFV starts in the heel at IC and advances forwards, it passes through the ankle at 5%. 0 – 5% of GC: GRFV posterior to ankle: ___ torque. 6 – 60% of GC: GRFV anterior to ankle: _____ torque. 61 – 100 of GC: where is the GRFV?? Muscles of the ankle: How can muscle activity be measured? Muscle strength: lever and cross section area.
Dorsiflexors: what are the dorsiflexors? Are generally swing phase muscles. Plantar flexors: what are the plantar flexors? Are generally stance phase muscles. Dorsiflexors: three, all have almost the same lever arm. Cross section: TA, EDL, EHL. Plantar flexors: 7 muscles pass posterior to ankle, only two are purely plantar flexors, which are??
Functional interpretation of the ankle: IC: Posture: neutral. GRFV: posterior Torque: ?? Muscle action required: ?? LR: Motion: PF (which represents?? what is this moion importance??) GRFV: posterior to anterior
Torque: ?? Muscle action required: ??? Muscle action serves to extend heel only support period (what does this mean?), and to nudge the tibia forward (how? Why is this important?).
Muscle action reduces the speed of tibial advancement, absorbs shock. MST: Motion: DF (what does this motion represent?) GRFV: ?? Torque: ?? Muscle action required: ?? Muscle action provides both controlled progression and stability. TST: Motion: DF (very slow, what does this motion represent?) GRFV: ??
Torque: ?? Muscle action required: ?? At the end of MST, the ankle is almost locked by muscular action, while DF torque causes the heel to rise making the forefoot the sole source of support. The DF torque is at its maximum, requiring very strong muscular contraction. Combined DF and heel rise put the GRFV anterior to the forefoot (outside the support area) resulting in a free forward fall of the body (this force is????). PSW: Motion: rapid PF. GRFV: anterior (small in magnitude, why???)
Torque: ??? Muscle action required: ??? Once body weight is transferred to the other foot, the need for strong muscular contraction no longer exists. (why body weight transfer occur in double limb support??). But how PF occur??? Push-off vs roll-off. Traditionally push-off is the term used to describe ankle motion and dynamics during pre-swing. Several facts contradicts this term: 1- Plantar flexors cease contraction (they don’t increase action) 2- the type of contraction is eccentric not concentric.
ISW: Motion: DF GRFV: ?? Torque: ?? Muscle action required: ?? The position of 20 PF degrees does not immediately hinder limb advancement as the tibia is still trailing backward, but the need for DF is urgent afterwards. MSW: Motion: DF or no motion. GRFV: ??
Torque: ?? Muscle action required: ?? Muscle action is needed to DF or to maintain a DF position of the foot to assist in limb advancement. TSW: Nothing really changes but the increased muscular contraction to ensure neutal ankle position at IC.