The Lower Leg and Ankle

June 16, 2006 @ 04:04 PM Filed in: Anatomy

The Mobile Base


The foot and ankle have a few basic movements for us to consider:

• inversion;
• eversion;
• supination;
• pronation;
• dorsiflexion;
• plantar flexion;
• adduction;
• abduction.


Adduction, in which the foot and toes turn in towards the midline, and abduction, in which the toes and foot turn out, are movements that we generally try to avoid in yoga, preferring that the action initiate in the hip rather than the foot/ankle. The remaining ranges of motion are all worth looking at in some detail.

Inversion of the foot


foot inversion
The sole of the foot turns inward towards the midline of the body. The inner foot, inner ankle and inner heel shorten.

Muscles:
• Tibialis anterior
• Extensor hallucis longus
• Flexor hallucis longus
• Flexor digitorum longus

Eversion of the foot


foot eversion
The sole of the foot turns away from the midline and the inner foot, inner ankle and inner heel lengthen. The outer foot sharpens.

Muscles:
• Extensor digitorum longus
• Peronius tertius
• Peronius longus
• Peronius brevis

Supination of the foot


supination of foot
A complex combination of movements that ends up with the weight being borne more on the outer edge of the standing foot than the inner edge.

Pronation of the foot


pronation of foot
A complex combination of movements that ends up with the weight being borne more on the inner edge of the standing foot than the outer edge.

Supination and pronation are important to know about as many of us have a tendency towards one or the other that might affect the way in which you use the feet in poses.

Dorsiflexion of the ankle


dorsiflexion of the foot
The foot is drawn up towards the shin and the heel sharpens.

Muscles:
• Tibialis anterior
• Extensor hallucis longus
• Extensor digitorum longus
• Peronius tertius

Plantar flexion of the ankle


plantar flexion of the foot
The top of the foot reaches away from the shin and the toes/toe mounds point.

Muscles:
• Peronius longus
• Peronius brevis
• Tibialis posterior
• Flexor hallucis longus
• Flexor digitorum longus
• Gastrocnemius
• Soleus



Bones of the lower leg and ankle


bones of the lower leg
articulations in the ankle

Muscles of the lower leg


The muscles of the lower leg are bundled together into four different compartments:

compartments of the lower leg

• the anterior compartment (front of the shin);
• the lateral compartment (outer edge of lower leg);
• the posterior compartment (what we generally think of as the calf);
• the deep posterior compartment (deep muscles behind the flesh of the calf).


Anterior compartment


These muscles dorsiflex the ankle and the toes.

Tibialis Anterior


Tibialis Anterior
Actions:
• Dorsiflexion of the ankle (flexing of the foot);
• inversion of the foot (rolling to the outer edge).

Extensor Hallucis Longus


Extensor Hallucis Longus
Action:
• Dorsiflexion of the ankle (flexing of the foot);
• inversion of the foot (rolling to the outer edge);
• dorsiflexes big toe (pulls it up).

Extensor Digitorum Longus


Extensor Digitorum Longus
Action:
• Dorsiflexion of the ankle (flexing of the foot);
• eversion of the foot (rolling to the inner edge);
• abduction of the foot (turns foot away from midline of body);
• dorsiflexes 2nd - 5th toes (pulls them up).

Peronius Tertius


Peronius Tertius
Action:
• Dorsiflexion of the ankle (flexing of the foot);
• eversion of the foot (rolling to the inner edge);
• abduction of the foot (turns foot away from midline of body).


Lateral compartment


These muscles assist in plantar flexion of the ankle.

Peronius Longus


Peronius Longus
Action:
• Plantar flexion of the ankle (pointing of the foot);
• eversion of the foot (rolling to the inner edge);
• supports transverse arch of foot.

Peronius Brevis


Peronius Brevis
Action:
• Plantar flexion of the ankle (pointing of the foot);
• eversion of the foot (rolling to the inner edge).


Posterior compartment


These muscles strongly plantar flex the ankle

Gastrocnemius


Gastrocnemius
Action:
• Plantar flexion of the ankle (pointing the foot).

Soleus


Soleus
Action:
• Plantar flexion of the ankle (pointing the foot).


Deep posterior compartment


Lies between the thick calf muscles of the posterior compartment and the tibia. They assist in plantar flexion.

Tibialis Posterior


Tibialis Posterior
Action:
• Plantar flexion of the ankle (pointing of the foot);
• inversion of the foot (rolling to the outer edge);
• adducts foot (turn into midline of body);
• supinates ankle (brings weight into outer edge).

Flexor Hallucis Longus


Flexor Hallucis Longus
Action:
• Plantar flexion of the ankle (pointing of the foot);
• inversion of the foot (rolling to the outer edge);
• flexes big toe (points it);
• supinates ankle (brings weight into outer edge).

Flexor Digitorum Longus


Flexor Digitorum Longus
Action:
• Plantar flexion of the ankle (pointing of the foot);
• inversion of the foot (rolling to the outer edge);
• flexes 2nd-5th toes (points them).