Ankle Joint

In sport the ankle joint is the most important joint in the body. It is the key joint and is responsible for the transfer of forces from the leg to the ground. It has to cope with changes in load, speed, direction and uneven surfaces all at the same time.

To be able to run about and take part in sport efficiently at any level you have to be able to control your ankle joint effectively. Control at the ankle joint is defined as the ability to balance your moving body over your foot as the foot moves over the ground.

By the end of this article you will have:-

• a good knowledge of the anatomy of the ankle joint
• know what movements take place at the ankle joint
• have an understanding of what proprioception is
• an understanding of how you balance at the ankle joints.

Ankle Joint Anatomy

To achieve balance the ankle joints have to work in harmony with the leg and the foot. I say ankle joints – plural.

It is more of an ankle complex consisting of a collection of joints as can be seen in the X-ray.

There is the joint between the two long bones of the lower leg – the thick Tibia and the thinner Fibula. This is the Inferior Tibio-Fibular Joint or High Ankle Joint

These two bones join together to provide the mortise or socket of the ankle joint.

Fitting into this socket is the Talus bone from your foot. If you remember from “Foot Fundamentals” this is the bone that sits at the apex of the inner longitudinal arch of your foot. This joint provides the link between your foot and leg and can be considered the ‘upper part of the ankle joint’

Situated below the Talus is the heel bone – the Calcaneum. The joint between the Talus and Calcaneum is called the Subtalar joint and it can be considered as the ‘lower part of the ankle joint’. This is quite a complicated joint with movements taking place in more than one direction simultaneously.

Ankle Joint Movements

The ‘upper ankle joint’ operates similar to a hinge providing up and down movement. The upward movement of the foot on the leg is called dorsiflexion, and the downward movement of the foot on the leg is called plantar flexion.

Performing plantar flexion in standing is the same as raising your heel and standing on your toes. As well as dorsiflexion and plantar flexion there is a tiny bit of side to side movement available in the joint but this is negligible.

At the ‘lower ankle joint’ when the foot is off the ground the inward movement of the heel is called inversion, and the outward movement of the heel is called eversion. The movement at this joint takes place in three directions simultaneously and this starts to complicate things when the foot is on the ground. See Ankle and Foot – a twisted relationship for a fuller explanation.

PROPRIOCEPTION

To balance at your ankle you need to be in control of these movements at all times. This is achieved by contracting the appropriate muscles at the correct time, for the required duration and intensity. All this is under the control of your brain. To control these elements the brain needs information from the area before it can decide what response to make. This information to the brain has been called your sixth sense, proprioception, and it works alongside the other five of Touch, Taste, Smell, Hearing and Sight.

Proprioception is described as the body’s ability to sense movement within joints and joint position. A simple example would be to close your eyes, stretch out your arm to the side and then bend your elbow to touch your nose with the point of your index finger. Although you take this for granted there many, many complicated processes involved in doing this.

You have the ability to sense where your shoulder and upper arm are, how much force to supply to your shoulder muscles to stabilise your upper arm and control its rotation, you then have to bend your elbow, rotate your forearm, position your wrist, select your index finger and then place it accurately enough to touch the small target of the point of your nose without poking your eye out! Not to mention what your torso and lower limbs must do to compensate for you moving your arm. Quite Remarkable!

This is achieved by processing information from specialised sensors in your muscles, your joints, your tendons and your skin followed by your brain responding to this input by supplying signals to the appropriate muscles at the correct instant.

If you now stand on one leg you are using your proprioception sense to control the muscles around your ankle and foot joints. A reminder of the main muscle groups crossing the ankle joint is shown below.

In addition to using the feedback from your ankle area you also use input from your eyes and your ears to balance. You may find it difficult to understand why your ears are involved in balance, but you may have experienced loss of balance with ear infections or coming off a ride at a fun fair, this input to the balance mechanism is provided by fluid-filled canals in your inner ear.

Your eyes are also a major contributor to balance. To demonstrate the input from your eyes – stand on one leg and get your balance, then close your eyes. Feel how much more difficult it is with your eyes closed!

In standing your bodyweight passes in front of your ankle and it is mainly your calf muscles which control your sway backwards and forwards. When standing on one leg, if your weight (or more correctly centre of gravity) falls to the outside of your foot then you use the muscles on the inside of your ankle to correct this. Likewise if your centre of gravity falls to the inside of your foot then you use the muscles on the outside of your ankle.

Imagine you and a partner trying to control a giant telegraph pole between you when you each have a guy rope attached to the top of the pole and you’ll get the idea of working together. When the pole moves towards you, your partner has to pull, but then the pole moves towards them and you have to pull and so on…

You now have an understanding of:-

The next post will deal with the more complicated combined movement of the foot and ankle together and how this affects your running.

Now read Ankle and Foot – a twisted relationship

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