We all like to evaluate our patients; hopefully on the table as well as observation while weight bearing. Here is some food for thought.
When your patient or client is lying on the table, do you pay attention to where there head is in space (ie the position of their head)? Why should you care?
Remember our post on facilitation (if not, click here)? That has something to do with it.
Here is the short story. Make sure the head is neutral and midline (lined up between the shoulders), there is good preservation of the cervical curve , with a small pillow supporting the neck, but not altering it’s angle.
The long story involves the vestibular system. It is a part of the nervous system that lives between your ears (literally) and monitors position and velocity of movement of the head. There are three hula hoop type structures called “semicircular canals” (see picture above) that monitor rotational and tilt position and angular acceleration, as well as two other structures, the utricle and saccule, which monitor tilt and linear acceleration. I think you can see where this is going….
The vestibular apparatus (the canals and the utricle and saccule) feed into a part of the brain called the floccular nodular lobe of the cerebellum, which as we are sure you can imagine, have something to do with balance and coordination. This area of the cerebellum feeds back to the vestibular system (actually the vestibular nucleii); which then feed back up to the brain as well as (you guessed it) down the spinal cord and to predominantly the extensor muscles.
So, what do you think happens if we facilitate (or defaciltate) a neuronal pool? We alter outcomes and don’t see a clear picture.
Look at the picture above. Notice the lateral semicicular canals are 30 degrees to the horizontal? If you are lying flat, they are now at 60 degrees. If the head is resting on a pillow and flexed forward 30 degrees, the canals are vertical and rendered inoperable. This could be good (or bad) depending on what muscle groups you are testing.
OK. HEAVY CONCEPT APPROACHING
So if we defacilitate the extensors, what happens to the flexors? Remember reciprocal inhibition (If not click here)? According to the law of reciprocal innervation, the flexors will be MORE FACILITATED. If the extensors are faciltated, they will appear MORE ACTIVE and the flexors LESS ACTIVE.
Wow. All this from head position…The key herer is to know what you are doing, This gait stuff can get pretty complex; but don’t worry. We aren’t going anywhere and are here to teach you.
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