Crossing the Mid-Line .... What does this mean?

**** Please note that I am not a medical professional. The following information is based on our own experiences. 
If you believe that you or your child has difficulty in crossing their mid-line, 
please consult with a trusted medical professional. ****

One topic that I have touched on briefly in a previous post is crossing the mid-line. I was recently asked why this was so important so I thought that I would revisit this topic.

So what is the mid-line?

The term "mid-line" describes the invisible and imaginary line that runs down the centre of our body and divides the body into the left and right. If you like, this line runs down our spine from the base of our skull, through all of our vertebrae to the bottom of our back. Literally.

Crossing our mid-line refers to having the ability to reach across this invisible line in the middle of our body with both of our arms and legs. Being able to cross our mid-line is an important developmental skill that is needed by everyone for many everyday tasks. Reading, writing, reaching to our feet to put on shoes, using a knife and fork, being able to put clothes on and off, hitting a ball with a bat, catching a ball ... all of these tasks and many more require us to be able to cross our mid-lines. Any time that your right (or left hand) crosses over to the opposite side of your body, you are crossing your mid-line.

Having the ability to cross over our mid-line is not an ability that babies are born with. Typically developing children develop the ability to cross their mid-lines through play. Reaching for toys, babies playing with their toes, exploring toys and other objects with their hands. drawing or painting and so on all assist in developing the ability to cross the mid-line.

When we spontaneously cross our mid-line with our dominant hand (in my case, my right hand as I am right handed,) then the dominant hand gets the practice that is needed to develop good fine motor control. If a child struggles to cross their mid-line, then both hands (and feet) will receive equal practice at developing skills. This then means that they will have less skilled hands rather than one more skilled, or dominant, hand.

L was one of those children who struggled to cross his mid-line. His inability to cross his mid-line became evident when he was drawing or painting. When drawing or painting on a piece of paper, if he wanted to draw or paint on the left hand side of the page, he would turn the page on the table to get to the spot that he wanted to decorate rather than move his hand across the paper. L was physically unable to put his hand across his body to the left hand side. It was also evident when he went to reach for toys that were across his body. If a toy was on his left hand side, he would only ever reach for it with his left hand and vice versa on the right hand side of his body. We also noticed that L was neither right or left hand dominant in other words, he'd use both hands (and feet) equally when completing tasks.

L also had difficult in swapping hands mid way through a task such as passing a crayon or toy from one hand to the other. L struggled, and still does, to dress himself. When engaging in fine motor control, L would usually end in a state of extreme frustration as he struggled to complete the task successfully. For a very long time, L would avoid colouring and drawing activities.

L's gross motor skills were well developed but when kicking a ball, he'd often use both feet (but not at the same time) to kick balls around the yard. This indicated that he was neither left or right dominant.

When L was in kindy he was desperate to be able to write his own name, but crossing the mid-line can be a pre-cursor to be being able to write from left to right on a page.

Having a difficulty in crossing the mid-line can also make it difficult for an individual to visually track a moving object from one side to the other of their body. L would move his entire head to track an object rather than just using his eyes.

Once I'd learnt a little more about the mid-line and the importance in being able to cross it, I was a little confused. When O was a new born, I'd learnt about baby massage and moving a babies arms across their bodies during play. O enjoyed this as a baby and L did to some extent. O didn't seem to have any struggles with crossing her mid-line and yet L did. And yet I'd done the same exercises with O and L. 

It wasn't until I was assured by L's Occupational Therapist that it was nothing that we did, or didn't do, as parents. Some children just need extra assistance in learning this skill.

Knowing all this got me thinking - how does crossing the mid-line actually develop?

Having the ability to cross the mid-line is important on a physical level as well as on the brain level. In terms of the brain level, if an individual is unable to cross their mid-line, this may indicate that the left and right sides of their brain (the left and right hemispheres) are not communicating well together. The left and right hemispheres communicate with each other across a mass of tissue called the corpus callosum and because each hemisphere carries out different neurological tasks, the two hemispheres need to work together.

Crossing the mid-line begins to first emerge in the infant years as a child begins to develop their bilateral coordination skills. They do this by using both hands to reach for toys and other objects, pulling and pushing themselves along the floor, crawling and so on.

Through play and exploration, a child will then learn to coordinate their strong hand or foot (or dominant hand or foot) when doing particular skills. They'll also develop their other hand or foot, their assistant or helping hand. For example when using scissors - their dominant hand will hold the scissors and their helping hand will hold the paper. Through play and exploration, they will also spontaneously cross their mid-line. They may be a little clumsy at first, but they will become more skilled at this.

Another factor in being able to cross the mid-line is trunk rotation. If a child has a low core stability, then this may affect their ability in being able to cross their mid-line. This comes back to proximal stability before distal mobility! L was, and still does, sit in a w position. When sitting in a w position, this can affect trunk rotation as the position itself places limitations on how much the individual can rotate their trunk. 

So armed with all of this information we set to work in assisting L to develop the ability to cross his mid-line, with the assistance of his therapists at the early intervention centre that he attended. Through play, L was practising crossing his mid-line on a daily basis but we also incorporated practising this skill into other activities at home.

• Drying dishes - One of L's favourite household chores is drying the dishes - one day, his future partner is going to love me! We used to have a small child's table that we used for various reasons in our house. I would seat L at the table, put the dish towel in his right hand and the wet dishes on the left hand side of the table. Through the action of reaching across the table to the wet dishes he was crossing his mid-line each and every time. I'd also encourage L to then try and use the dish towel in his left hand and the dishes on the right hand side of his body so that both sides had an equal opportunity to practise the skill.

• We'd encourage, and still do, L to dress himself so that both sides of his body could work together.

• Painting - I'd always put the paint on the opposite side of the table and ask L to try and reach the paint without moving his body. Again, every time he reached for the paint, he'd have to cross his mid-line.

• Car letters and numbers - We have created a game board for L to practise his letter and number recognition skills. I have put letter and number stickers on the top of toy cars and have laminated words that L wanted to learn how to spell. L sits directly in front of the board and we put the cars that he needs to his left. Again when he reaches for the cars that he needs, he has to cross his mid-line!

• We have balance boards and gym balls that L will sit on and bounce on, all the while developing his core stability.

• We'd play ball games and we'd encourage L to catch and throw a ball with both hands.

• When we noticed that L was seated in a w-position, we'd encourage him to sit with his legs out in front or with his back up against the furniture or the wall so that we could develop his core stability.

In the beginning of our journey, we would model to L on how to do the skill. This helped tremendously in L being able to successfully complete the skill. And when he became frustrated, we'd offer him reassurance and encouragement! Three years on and we still practise this skill with L. He still becomes frustrated to an extent, but his ability to cross his mid-line in now much stronger.

Proximal Stability before Distal Mobility .... What????

*** I am not a medical professional, all of the content in this post is based off of our own experiences. If you feel that your child would benefit from increasing their proximal stability, please consult a trusted medical professional. ****

I think it is truly amazing that no matter how far we are along our autism journey with O and L, we never stop learning. There is always a new facet of autism to learn about and last week was no different.

L has mentioned on numerous occasions over the last few weeks that the reason he doesn't want to go to school is because his hand starts to hurt when he has to do a lot of writing. We've also noticed at home, both recently and over the past few years, that he tires very easily when he is colouring or painting. In the past we've always put this down to L becoming bored of the activity but little did we know, it had more to do with his muscles tiring than with being bored.

When we mentioned this to his Occupational Therapist recently, she said it all had to do with L's proximal stability needing to be further developed before we could work on his distal mobility.

Huh??? I really must work on my stunned goldfish look!!

Prior to beginning our autism journey I had never heard of proximal stability or distal mobility.

So let's first talk about the first part of this statement - what is proximal stability?  Well, prepare to be enlightened!

Proximal stability refers to the chain of muscles that start at our core and go out towards our extremities. When we use the tiny muscles in our hand to complete fine motor tasks, we must first have a stable chain of muscles that run from our core muscles to our shoulder to our elbow, wrist and then to our fingers.

If that chain of muscles beginning at our core is not stable and strong, then it will be very difficult for us to hold a pen or pencil for a long period of time. Without good proximal stability, we also may have difficulty in maintaining an upright seated position when seated at a desk throughout the day.

And therein lies the issue for L. As his core is not as strong as it should be, the chain of muscles leading to his fingers are not as strong as they should be and hence his hand hurts when doing writing.

The second part of the statement, distal mobility, refers to the functions of our hands and our feet - or our fine motor control. To have good distal mobility we first need a strong chain of muscles or a strong proximal stability. 

In other words before we can have correct and effective function in our hands and feet, we need to work on strengthening the chain of muscles starting at the inside and working towards the outer muscles.

Proximal stability BEFORE distal mobility!

A simpler way to think about this concept is to think of it in terms of a baby learning to move around. Babies generally have a lot of mobility, L certainly did anyway, but not a lot of stability to begin with. A baby will develop their head and trunk control and strength long before they learn to sit up. A baby needs to develop their head and trunk control and strength in order for them to be able to sit up. Head and trunk control really are the building blocks for other physical movements for children.

Another way to think about this concept is when babies and toddlers are learning to draw or paint. When first learning to draw or paint, a child will use their entire arm to scribble or paint on paper or walls or furniture or whatever other medium that they are decorating. As the child's skills develop, they begin to rest their forearm on the table and then the movements are narrowed further to develop their fine motor control.

So it makes sense then that if a child is struggling to control a writing utensil or if they require constant assistance for other fine motor tasks, then they may lack the core stability or the stability along the chain of muscles required to do the fine motor task.

This concept makes a lot of sense for some of the things that O struggles with as well. O struggles to hold herself up when she wheelbarrow walks on her arms or when she tries to hang on the monkey bars. She lacks the strength along the chain of muscles to complete these tasks.

Both O and L tire easily when walking and riding their bikes or scooters. Again we always thought that they were simply running put of energy, but no, this also has to do with their proximal stability and the chain of muscles leading out from their core.

It is important to keep in mind that strengthening this chain of muscles from the core out takes time. At times it is important to shorten the chain and work on a small section at a time so that the child doesn't tire too quickly or become frustrated when they struggle with the task. If they are able to achieve a small task then the chances are that they'll more likely want to participate in future activities.

And as our Occupational Therapists have said on numerous occasions, they will often focus on the working on the building blocks before they work on the end goal for O and L.

If proximal stability and fine motor control were represented as a brick wall - proximal stability would be on one of the bottom rows of the wall and fine motor control would be towards the top of the wall. If the bottom row of the wall is not stable, the upper most rows will not be stable! There is no point in developing fine motor control if L is struggling to hold a pencil for a long period of time.

So how can we strengthen this chain of muscles or a child's proximal stability?

L and O love rolling over their peanut ball. I will put toys or other objects on the floor that they have to reach out to get from the peanut ball. The idea is that they have to lie on the peanut ball and use their hands to "walk" towards the objects. They then have to pick up an object and "walk" back on their hands to the start. This strengthens their core as well as their shoulder muscles.

We do a lot of activities and games with the little superheroes lying on their tummies as this helps to stimulate their core muscles and strengthen their shoulder muscles as they hold their head and shoulders up to complete the activity. We also encourage them to sit in different positions such as long legged sitting or on a wobble cushion as they play as this also assists in strengthening their core muscles.

During therapy sessions, L will stand or kneel to write or draw on the vertical whiteboards in the therapy rooms which assists in strengthening his shoulder muscles. Kneeling and standing stimulates different muscle groups along the chain running out from L's core and as such both actions help his muscles to become strong and stable.

We encourage O and L to climb on play equipment or trees when we visit our local parks as this helps to strengthen their core muscles and the chain of muscles out to their limbs.

We also do activities to strengthen L and O's muscles in their hands. Their most favourite activity is the monster tennis ball. These are very easy to make - you simply need to cut an opening into a tennis ball making sure that it is wide enough to open to represent a mouth but not too wide that the tennis ball splits in half. The idea is that the ball is held between the thumb and pointer finger and you use these two fingers to squeeze the ball to open to put small items into the monsters mouth. This action of squeezing the tennis ball open, strengthens the muscles in the hand that are used for fine motor control.

There are many other options for strengthening a child's proximal stability. The one point to remember is that proximal stability needs to be strong before we start working on fine motor control!

Proximal stability BEFORE distal mobility!