Crossing The Midline

Are you wondering what crossing the midline is all about? Read on for more information and some helpful tips!

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When Occupational Therapists and other professionals talk about “midline crossing”, the midline they are referring to is an imaginary line drawn from the head to the feet that separates the left and the right halves of the body.

Child spontaneously crossing the midline

Crossing this midline means that a body part (eg hand or foot) is able to spontaneously move over to the other side of the body to work there. 

Before this ability is well established, you may have noticed that your young child may tend to use the left hand on the left side of the body and the right hand on the right side of the body.


Why Midline Crossing Is Important

The ability to cross the midline is important on the physical level as well as on the brain level.

On the brain level, a lack of midline crossing may indicate that the left and right sides of the brain (the left and right hemispheres) are not communicating well together.

The left and right brain hemispheres communicate across a mass of tissue called the corpus callosum. Because each hemisphere carries out different tasks, it is important for each hemisphere to communicate with the other across the corpus callosum in order to coordinate learning and movement.

On a physical level, when your child spontaneously crosses the midline with the dominant hand, then the dominant hand is going to get the practice that it needs to develop good fine motor skills.

If your child avoids crossing the midline, then both hands will tend to get equal practice at developing skills, and your child’s true handedness may be apparently delayed and fine motor skills may not be as good as they could be.

One of the factors affecting handwriting is having a specialized, strong hand that does a good job of controlling the pencil.

If both hands are being used equally, then your child may well end up with 2 mediocre hands rather than one strong, specialized hand.

And mediocre hands do not produce great handwriting!

Some children with poor midline crossing skills go to school having developed a dominant hand, but may have developed some “compensatory mechanisms” that make writing really awkward for them.

This girl has turned the paper sideways so she can write from bottom to top, instead of reaching over to her left side with her right hand to write from left to right.

This boy has shifted his body way over to the left, so his right hand does not have to reach over to work on his left side.



How Crossing the Midline Develops

On a physical level, crossing the midline emerges as your child develops bilateral coordination skills. First, the two sides of the body need to learn to work well together doing the same thing (eg pulling, pushing, crawling).

As your child learns to coordinate a strong hand which is doing something skilled (eg cutting) and an assistant hand which is helping (eg holding the paper), the ability to spontaneously cross the midline develops even more.

Find out more about this process of developing handedness and see how midline crossing fits into your child’s development.

However, there is another vital factor in crossing the midline, and that is trunk rotation. If your child tends to have poor core stability, or holds him or her self “stiffly”, moving the body as a unit, then this may affect crossing the midline.

You can see this in action in the photos below:

This child has turned her lower body WITH the upper body, so the shoulders and the hips have both turned.

There is no trunk rotation, and no midline crossing!

Using this position, the child’s upper body has turned around (rotated), while her lower body (hips and legs) remains facing forward.

There is some trunk rotation and the child is crossing the midline with her dominant hand


If you are concerned about midline crossing, your OT should also assess bilateral coordination skills and core stability and trunk rotation.

Use these tips for positioning your child, and check out the links to other helpful activities on my site at the end of this page.


Positioning to Cross the Midline


This right handed child is avoiding crossing his midline and is using his left hand to pick up the cards on his left side during a game.


So, gently hold his left hand down so that he reaches with his right hand across his midline.


With an older child, prompt him to keep his assisting hand resting on the side of the table.


Then he will use his dominant hand to reach across the midline for the next card that he needs.

Although this girl is crossing the midline during her game, her left hand (assistant hand) is on the chair. Rather cultivate the habit of having the assistant hand on the table as described above.

If your child is doing a worksheet or drawing activity, watch out for the subtle shifting of the page to the “dominant hand” side. If you look closely, this boy only has to reach over as far as his midline (the shirt buttons) with his pen.
    


A small shift in the paper means that he is now crossing his midline a little bit in order to draw the lines

Working on a vertical surface is great, but your child must be positioned directly in the center of the shape to be drawn, and the assistant hand must be on the board as shown!

You may also find some helpful ideas on these activity pages:

Or check out my gross motor e-books for a wealth of activity ideas to do at home...there are a few midline crossing ideas in the e-books, too.

Free Midline Crossing Handout!

You may share this free PDF download to help others. But please do not link directly to the PDF from your own blog - rather link to this article. Thank you!

Midline Crossing Information And Tips  (106KB)


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› Crossing The Midline

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