Week 2: Human Gait Flashcards
Describe the normal gait cycle.
STANCE phase (60%) 1. Heel strike-double support 2. foot flat 3. mid stance 4. heel off 5. pre-swing-double support SWING phase (40%) 6. early swing 7. late swing 8. heel strike
How is pelvic tilt controlled during gait?
- the swinging leg has wt of limb and gravity pulling it downward
- to prevent sagging, gluteus medius and minimus on opposite leg contract isometrically to prevent sagging (femur pulls down on pelvis to elevate opposite side)
How is pelvic rotation controlled during gait?
- if left neutral, the advancing foot would face medially (pigeon toed)
- lateral rotators contract to produce slight lateral rotation to keep foot pointed straight ahead
- lateral rotators: piriformis, obdurator internus, obdurator externus, and quadratus femoris
- don’t need to know nerve supply
In an upright individual, draw a vertical line of gravity relative to the sacral promontory and hip, knee, and ankle joints.
- the line passes behind the sacral joint, in front of the knee and ankle joint
- backward leaning of trunk relative to hip joint prevented by iliofemoral ligament on anterior side of hip joint
- posterior knee joint capsule, cruciates, and collaterals prevent hyperextension at the knee
- soleus muscles and some fine tuning by erector spine prevents swaying forward at the ankles
- to stand upright, only muscle activity is the soleus to keep from losing balance
What muscles are active during heel strike?
- Gluteus maximus and hamstrings contract isometrically to prevent trunk from jack knifing
- ankle dorsiflexors contract eccentrically to allow for controlled lowering of foot to ground
- gluteus medius and minimus contracts isometrically to stabilize pelvis to prevent tilt
What muscles are active during foot flat?
- gluteus medius and minimus contract isometrically preventing pelvic tilt
- quadriceps contract eccentrically to control unwanted knee flexion due to body wt.
What muscles are active during mid-stance?
- gluteus medius and minimus: prevent pelvic tilt
2. plantar flexors (gastrocnemius, soleus, TP, FHL) contract eccentrically to prevent unwanted dorsiflexion
What muscles are active during heel-off?
- plantar flexors contract concentrically to thrust leg forward
- iliopsoas contracts concentrically to bring thigh forward
What muscles are active during pre-swing/toe off?
- plantar flexors contract concentricallly to propel forward
- iliopsoas contract concentrically to bring thigh forward
What muscles are active during early swing?
- ankle dorsiflexors (TA, EDL, EHL) contract concentrically to dorsiflex ankle so foot clears ground
- iliopsoas contract concentrically to bring thigh forward
- quads, particularly rectus fermoris, contract isometrically to prevent excessive flexion at knee
What muscles are active during late swing?
- ankle dorsiflexors (TA, EDL, EHL) contract isometrically to hold ankle in neutral position to keep toes from stubbing ground and to ready for heel strike
- hamstrings contract eccentrically to slow forward momentum of leg, also acts at hip to slow forward momentum of trunk to prevent jack knifing
Describe a Trendelenburg gait and what lesion can cause it.
- lesion of superior gluteal nerve
- paralyzes gluteus medius and minimus, and tensor fascia latae.–>excessive pelvic tilt on opposite side
- bilateral lesions result in waddling gait
What does a lesion of nerve supply to the iliopsoas muscle result in?
-impossible to walk since limb can’t be brought forward
How does a tibial nerve lesion affect gait?
- paralyzes hamstrings
- forces patient to lean backwards at heel strike
Describe the gait of a femoral nerve lesion paralyzing the quadriceps.
Patients with this lesion can’t prevent supporting limb from collapsing into flexion of the knee at heel strike. They allow forward momentum of leg to carry knee into extension just prior to heel strike to compensate, and lean forward at trunk to position center of gravity in front of knee.
