Kinesiology of the Ankle

Kinesiology of the Ankle:

By Dr. Brent Brookbush, DPT, PT, MS, CPT, HMS, IMT

From the Course:

• Lesson 21: Functional Roles of Muscles

Additional Courses

• Lesson 16: Ankle Joint Actions and Muscles (Introductory Course)
• Ankle Joint Anatomy: Talocrural, Subtalar, and Tibiofibular Joints (Advanced Course)
  

Definitions:

• Prime Mover : The muscle that can produce the most force for a joint action. Generally, this is the muscle that will generate the most force during a joint action when exerting force against an external load.
• Agonist : Muscles that perform a joint action, including the prime mover and synergists. That is, unlike the terms prime mover and synergist, agonist refers to all of the muscles that can perform a joint action.
• Synergist : Synergists are muscles that assist the prime mover in performing a joint action. By definition, all agonists that are not the prime mover are synergists.
• Antagonist : Muscles that oppose the agonists (including the prime mover and synergists) for a given joint action. That is, all of the muscles that can perform the opposing joint action.
• Neutralizer : During a joint action, neutralizers are muscles that oppose the unwanted or ancillary joint motions that result from the force generated by the prime mover and/or synergists.
• Fixator : Fixators are muscles that act to reduce or prevent movement of joints proximal to the joint in motion.
• Stabilizer : The role of a stabilizer is to improve arthrokinematics by maintaining optimal alignment of joint surfaces during joint actions. Most often, these muscles are the most intrinsic muscles of a joint. For example, the muscles of the rotator cuff of the shoulder.
  
  

Kinesiology of the Ankle Joint

Ankle Plantar Flexion

• Prime Mover: Soleus , gastrocnemius
• Synergists: Fibularis longus, fibularis brevis , tibialis posterior , flexor hallucis longus, flexor digitorum longus , plantaris
• Antagonists: Tibialis anterior , extensor digitorum longus, extensor hallucis longus, fibularis tertius
• Neutralizers: The tibialis posterior  and medial gastrocnemius neutralize the eversion force created by the soleus , lateral gastrocnemius and the fibularis muscles .
• Stabilizers: Fibularis longus , fibularis brevis , fibularis tertius , tibialis posterior , flexor hallucis longus, flexor digitorum longus , extensor hallucis longus, extensor digitorum longus
• Fixators: Medial and lateral stabilizers of the knee, quadriceps , musculature of the foot

Ankle Dorsi Flexion

• Prime Mover: Tibialis anterior
• Synergists: Extensor digitorum longus, extensor hallucis longus, fibularis tertius
• Antagonists: Soleus , gastrocnemius , fibularis longus, fibularis brevis , tibialis posterior , flexor hallucis longus, flexor digitorum longus , plantaris
• Neutralizers: The fibularis tertius and extensor digitorum longus neutralize inversion force created by tibialis anterior and extensor hallucis longus . The toe flexors stabilize the toe extension force created by extensor hallucis longus, and extensor digitorum longus .
• Stabilizers: Fibularis longus, fibularis brevis , fibularis tertius , tibialis posterior , flexor hallucis longus, flexor digitorum longus , extensor hallucis longus, extensor digitorum longus
• Fixators: Medial and lateral stabilizers of knee, quadriceps , popliteus , musculature of the foot.

Ankle Inversion

• Prime Mover: Tibialis anterior , tibialis posterior
• Synergists: Medial gastrocnemius , flexor hallucis longus, flexor digitorum longus , extensor hallucis longus, plantaris
• Antagonists: Soleus , lateral gastrocnemius , fibularis longus, fibularis brevis , fibularis tertius, extensor digitorum longus , plantaris
• Neutralizers: Careful balance between groups is important to prevent unwanted ancillary motion. It is difficult to name specific neutralizers, as inversion rarely occurs in isolation.
• Stabilizers: Fibularis longus, fibularis brevis , fibularis tertius , flexor hallucis longus, flexor digitorum longus , extensor hallucis longus, extensor digitorum longus
• Fixators: Medial and lateral stabilizers of knee, quadriceps , popliteus , musculature of the foot.

Ankle Eversion

• Prime Mover: Fibularis longus, fibularis brevis
• Synergists: Fibularis tertius , soleus , lateral gastrocnemius , extensor digitorum longus
• Antagonists: Tibialis anterior , tibialis posterior , medial gastrocnemius , flexor hallucis longus, flexor digitorum longus , extensor hallucis longus
• Neutralizers: Careful balance between groups is important to prevent unwanted ancillary motion. It is difficult to name specific neutralizers, as eversion rarely occurs in isolation.
• Stabilizers: Fibularis tertius , tibialis anterior , tibialis posterior , flexor hallucis longus, flexor digitorum longus , extensor hallucis longus, extensor digitorum longus
• Fixators: Medial and lateral stabilizers of knee, quadriceps , popliteus , musculature of the foot.

Ankle Dorsi Flexion and Inversion

• Prime Mover: Tibialis anterior
• Synergists: Extensor hallucis longus
• Antagonists: Soleus , lateral gastrocnemius , fibularis longus, fibularis brevis , plantaris
• Medial gastrocnemius , tibialis posterior , flexor hallucis longus, flexor digitorum longus , extensor digitorum longus, fibularis tertius
• Neutralizers:In this analysis we could view those muscles that act as synergists in one, but not both joint actions as neutralizers of excessive motion. In this case those muscles would be:
  • Invertors: Medial gastrocnemius , tibialis posterior , flexor hallucis longus, flexor digitorum longus
  • Dorsi Flexors: Extensor digitorum longus, fibularis tertius
• Stabilizers: Fibularis longus, fibularis brevis , fibularis tertius , tibialis posterior , flexor hallucis longus, flexor digitorum longus , extensor hallucis longus, extensor digitorum longus
• Fixators: Medial and lateral stabilizers of knee, quadriceps , popliteus , musculature of the foot.

Ankle Plantar Flexion and Eversion

• Prime Mover: Soleus , lateral gastrocnemius
• Synergists: Fibularis longus, fibularis brevis , plantaris
• Antagonists: Tibialis anterior , extensor hallucis longus
• Neutralizers: In this analysis we could view those muscles that act as synergists in one, but not both joint actions as neutralizers of excessive motion. In this case those muscles would be:
  • Evertors: Fibularis tertius, extensor digitorum longus
  • Plantar flexors: Medial gastrocnemius , tibialis posterior , flexor hallucis longus, flexor digitorum longus
• Stabilizers: Fibularis longus, fibularis brevis , fibularis tertius , tibialis posterior , flexor hallucis longus, flexor digitorum longus , extensor hallucis longus, extensor digitorum longus
• Fixators: Medial and lateral stabilizers of knee, quadriceps , popliteus , musculature of the foot.

© 2011 Brent Brookbush

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