Walking is an example of the superb integrative action of the nervous system. It is not a learned series of consecutive motor acts but appears as an innate, gestalt phenomenon when other motor skills are still quite primitive, for example, a child may learn to walk at an age when he cannot yet feed himself.
If walking has an anatomical "center," the location is unknown. (Both the cat and the dog can walk after bilateral hemispherectomy.) Walking can be lost, and this may not be explained in terms of a discrete lesion. This is called gait apraxia and is often associated with dementia and frontal lobe signs. However, many demented people have normal gait, and gait apraxia occurs with normal intelligence.
Watch people without gait disorders walk from the front, back, and side.
Considering that the entire weight of the moving body can be continuously transferred from one foot to the other, every three quarters of a second, in a perfectly rhythmic way, without conscious effort, and even while we are preoccupied with some other matter, then walking must be one of the great functions of the nervous system.
When one steps out with the right foot first, three things happen almost simultaneously to the right lower limb. The right hip flexes (the knee comes away from the floor), the right knee flexes (the foot comes away from the floor), and the right ankle plantar flexes in every step except the first one. All the weight is on the left lower limb and, as the right leg comes forward and passes the left, there is more right hip flexion and the beginning of right knee extension and right ankle dorsiflexion in preparation for the transfer of weight to the right heel and foot. While this swing-through of the right leg is progressing, and starting just after the right leg passes the left one, the left ankle plantar flexes in preparation for the push it is about to give to the floor. Pay particular attention to the foot and ankle movements. The right heel strikes the floor with the ankle dorsiflexed and the weight of the body on the left foot. As the body comes forward, the right foot flexes and the right lower limb, with the knee extended, takes the weight of the body. The left foot plantar flexes and pushes off against the floor.
The arms reciprocate with the legs. As the left foot comes forward, so does the right upper limb.
Ask the patient to get out of the chair, walk away from you (6-7 m or so), turn quickly to his left, and without a pause walk back toward you. When he reaches you, have him turn quickly to his right and repeat the process.
The quick turn may evoke an ataxia not seen otherwise. TESTS
If ordinary walking is normal, add a number of tests that may elicit an abnormality.
Have the patient walk a straight line, heel to toe. He should put the right heel immediately in front of the left toes and then the left heel immediately in front of the right toes and so on.
Most people can walk this way across the examining room. If the patient cannot, this itself is not a localizing sign, but it does tell you that something is wrong.
• Have the patient walk on his tiptoes forward across the examining room.
• Ask him to walk on his heels backward across the examining room.
• Ask him to hop across the room on one foot and then the other.
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