Muscles & gait

Question 1

When is the gluteus maximus active and what does it do?

Answer 1

Contracts during late swing and early stance phase

Decelerates flexion and initiates hip extension: mildly contributes to hip abduction

Question 2

When is the gluteus medius active and what does it do?

Answer 2

Frontal plane stabiliser of the pelvis
Contracts during late swing phase, through midstance and propulsion
Prevents lowering of contralateral pelvis
Brief burst at toe off

Question 3

When is the gluteus minimus active and what does it do?

Answer 3

Antagonistically with glute med in early stance

Question 4

When is the illiocostalis lumborum active and what does it do?

Answer 4

Assists in frontal planes stability of the pelvis
Peak activity in early and mid propulsion
Contraction prevents exaggerated ipsilateral pelvis lowering in swing

Question 5

When is the TFL active and what does it do?

Answer 5

Contraction through late contact (acts to balance the force placed on the ITB by simultaneous contraction of gluteus maximus)
Contracts late propulsion and early swing (assists illipsoas with hip flexion)

Question 6

When is the illipsoas active and what does it do?

Answer 6

Peak activity during terminal stance and early swing

Assists adductors, TFL, rectus femoris, satorius with hip flexion

Question 7

When is the satorius active and what does it do?

Answer 7

Only active during swing phase
Peak activity shortly after toe off
Assists knee and hip flexion simultaneously internally rotating tibia during first half of swing phase

Question 8

When are the adductors active and what do they do?

Answer 8

Adductors - magnus, brevis and longus
Peak activity: toe off, flexion of hip and assist internally rotating swing phase femur
Pre tense before initial contact

Question 9

When are the hamstrings active and what do they do?

Answer 9

Hamstrings - biceps femoris, semitendinosus, semimembranosus
Peak activity: terminal swing, decelerates forward motion of rapidly extending leg
Contract through most of stance phase: assist glute max with decelerating flexion and initiating extension of hip joint

Question 10

When are the quadriceps active and what do they do?

Answer 10

Quadriceps - rectus femoris, vastus lateralis, vastus medialis, vastus intermedius
Pre-tense in late swing phase
Peak activity: early contact to decelerate knee flexion
Maintain contraction until CoM passes in front of knee
Brief activity late stance and early swing as Rectus femoris acts to assist hip flexion

Question 11

When are the anterior leg compartment muscles active and what do they do?

Answer 11

Anterior leg - tibialis anterior, – EHL, EDL, peroneus tertius
Peak activity: after heel strike, eccentrically decelerates plantarflexion
- Inactive: midstance through to terminal stance except continued activity in running
- TA contributes to ankle dorsiflexion with simultaneous DF & inversion of the 1st ray
- EHL acts to maintain tension on the hallux during late stance and early swing

Question 12

When are the posterior leg compartments muscles active and what do they do?

Answer 12

Posterior leg compartments - tib posterior, FDL, FHL
Tib post: in mid-stance to decelerate STJ pronation
- FHL & FDL: terminal mid-stance, assisting with heel lift by decelerating forward momentum with proximal tibia
- FDL: contact through most of propulsion as plantiflexors and maintain the digits plantigrade

Question 13

When are the gastro and soleus active and what do they do?

Answer 13

Peak activity: terminal mid stance (produce heel lift)
Soleus: prevents forward movement of proximal tibia (decelerates and stops ankle dorsiflexion)
Gastrocnemius: flexes knee and plantar flexes ankle
During contact:
Soleus decelerates internal tibial rotation
Gastro decelerates internal femoral rotation
Gastroc assists STJ supination

Question 14

When are the peroneus longus and brevis active and what do they do?

Answer 14

• During mid stnace the peroneal create pronatory force at STJ that partially resist supinatory forces generated by superificial and deep posterior compartment muscles
• Contraction of PL acts to stabilise the midfoot and works synergistically with TP to create compressive forces on the tarsals
• PB creates stabilising compressive force by pulling 5th metatarsals into the cuboid, into the calcaneus
• Contraction through propulsion: PL plantarflexes 1st ray, they both act together to evert the locked lateral column (transferring body weight medially, for high gear toe off)

Question 15

When are the adductor and abductor hallucis muscles active and what do they do?

Answer 15

Stabilise proximal phalanx of hallux against the ground:

• maintain plantarflexion tension of the 1st MTPJ
• transverse plane stabilisation of hallux
• abductor hallucis plantarflexes 1st MTPJ

Question 16

When are the flexor hallucis brevis and flexor digitorum brevis active and what do they do?

Answer 16

FHB: stabilises proximal phalanx

• functions with FHL and creates compressive force at the 1st MTPJ, helps maintain hallux on ground during propulsion
• FDB When functioning with FDL to compress 2-5 MTPJs, allows lesser digits to maintain effect ground contact during propulsion

Question 17

When are the interossei and lumbricals active and what do they do?

Answer 17

• Interossei: late mid-stance and propulsion to maintain transverse plane stability of 2-5 MTPJs & compress proximal phalanx against metatarsal heads
• lumbircals: compress intermediate and distal IPJ’s while maintaining lesser digits against the ground by creating plantarflexory force about the MTPJs
• Lumbricals: mildly abduct MPTJs
• Interossei: plantarflexors of the proximal phalanx and maintain extensor rigidity through mid-stance and propulsion