Locomotion

What is the gait cycle?

It is the period from the initial contact (heel strike) of one limb, until the next time that heel hits the ground.

What are the two divisions of the gait cycle?

• stance phase

• swing phase

What % of the gait cycle is stance phase?

60%

What % of the gait cycle is swing phase?

40%

How does the running cycle differ from the gait cycle?

Running cycle contains a period of time when both feet are off the ground

• ‘double float’

stance = 40%
swing = 60%

Action of gluteus maximus?

Extension at the hip

Action of gluteus medius and minimus?

Adduction at the hip

Action of tibialis anterior?

dorsiflexion

Action of gastrocnemius, soleus and plantaris?

Plantarflexion (point toes)

What are the 5 primary functions of the nervous system in relation to locomotion?

• motor control

• reflexes

• coordination

• sensory feedback

• gait control

What parts of the brain are engaged in locomotion?

• Cerebral cortex

• Cerebellum

• Basal ganglia

• Brainstem

What are CPGs?

Central pattern generators - neural circuits in the spinal cord that generate rhythmic, repetitive patterns of motor activity

• no need for higher input

Where is the body’s COG?

Within the pelvis - midline anterior to sacral vertebrae

What determines stability?

The relationship between the base of support and the position of the body’s COG

What helps to control stability when standing?

Ankle strategy
- alternating between dorsiflexion and plantarflexion to restore COM

What is Trendelenburg gait?

Where the pelvis drops when good limb enters swing phase because small gluteal muscles on the opposite side of the pelvis cant hold the pelvis level
- LUMBAR spine flexes toward the paralysed side to bring CoG over foot in stance phase

What causes Trendelenburg gait?

Dislocation of the hip/paralysis prevent effective functioning of small gluteals

What is coxa vara?

Coxa vara = decreased angle at hip joint (<120 degrees)

What is coxa valga?

Coxa valga = increased angle at the hip joint (>140 degrees)

What gait is a consequence of coxa vara?

duck waddle gait - shortening of lower limb and limits passive abduction of hip

What gait is a consequence of coxa valga?

Weakness of adductor muscles and lack of normal weight baring forces
- associated with cerebral palsy

What makes up the stance phase?

• initial contact (heel strike)

• loading response (flat foot)

• midstance

• terminal stance (heel off)

• pre-swing (toe off)

What are the components of the swing phase?

• initial & midswing

• terminal swing
  

What is antalgic gain?

Limp - reduced loading of painful limb

• shortened stance phase

• longer swing phase

• longer step length

Causes of antalgic gait?

Diabetic foot

Osteoarthritis

Trauma

What is ataxic gait?

Unsteady and uncoordinated walk with wide base
- feet are thrown out

What can cause ataxic gait?

• MS

• Cerebellar diseases

What is parkinsonian gait?

Short, accelerated steps - shuffling

Often on tip toe with trunk flexed forward

Causes of parkinsonian gait

parkinson’s, basal ganglia disorders

What is myopathic gait?

Waddling - pelvis tilts towards the non-weight baring leg

What causes myopathic gait?

Muscular diseases - that cause weakness in proximal pelvic girdle

What is neuropathic gait?

High stepping gait to avoid dragging toe because of foot drop

Causes of neuropathic gait?

Peripheral nerve disease

What is hemiplegic gait?

Motor impairment on one side of the body
- arm held to one side and effected leg is dragged due to weakness of distal muscles

Causes of hemiplegic gait?

Stroke or TBI

What is diplegic gait?

Motor impairment of both lower extremities
- tightness in muscles (especially the hip adductors)
- this causes legs to cross in the midline (scissor gait)
- circumduction during swing

Causes of diplegic gait?

Cerebral palsy