What is “mid-line crossing” all about?Mid-Line Crossing is a concept based on an imaginary line down the centre of the body, termed “the mid-line”, which divides the body into left and right; and being able to “cross the body’s mid-line” means one can reach across the middle of one’s body with one’s arms and legs. By the age of 3, a child’s bilateral co-ordination should be established well enough for him to be able to spontaneously reach across from one side of his body to the other. This allows him to perform an action on the opposite side of his body, such as drawing a horizontal line across a page without having to switch hands in the middle, or being able to insert puzzle pieces using the dominant hand when the puzzle is placed on the opposite side of the body. Even sitting cross-legged on the floor entails crossing the body’s mid-line.
Why is crossing the body’s mid-line important?Crossing the body’s mid-line is an important developmental skill. Many everyday tasks require it: writing, dressing, hitting a ball. A lack of mid-line crossing may indicate that the left and right sides of the brain are not communicating well together. Communication between the two hemispheres in the brain takes place across a mass of tissue called the corpus calossum. It is important for the two sides to communicate effectively, in order to ensure there is correct co-ordination on both sides of the body. Each hemisphere performs different functions, which have to be coordinated if proper movement as well as learning is to take place. When a child spontaneously crosses the mid-line, his dominant hand receives all the practice needed to develop strong fine-motor skills. Repeated, consistent hand dominance needs to be established at an early age in children, in order to master numerous skills at school-age. For instance, as a child learns to co-ordinate a strong hand which is doing something like cutting, his assisting hand is helping by holding the paper, and this reinforces mid-line crossing even more. If a child avoids crossing the mid-line, both hands get equal practice in different skills, but this will give him two mediocre hands and delay his true handedness. This means, once he starts more formal education (school), he will have much more difficulty learning to write because he has two less skilled hands rather than one stronger, more skilled (dominant) hand. Crossing the mid-line is also important because without it, the child will have difficulty in visually tracking moving objects from one side to the other. More importantly, being able to track from left to right is essential for reading. So delayed development in mid-line crossing will mean delayed reading ability. There is another significant aspect to mid-line crossing, and that is trunk rotation. Strong torso muscles are essential for core stability, to ensure flexibility and rotational strength so that the body can move as a unit, but also be able to bend and twist at the waist. If a child holds himself stiffly, it may affect his ability to cross the mid-line.
You can see that mid-line crossing is essential to help prepare a child for the transition into the academic environment where many pencil skills and fine motor tasks are expected (which require effective crossing of the body’s mid-line). It also contributes significantly to a child’s reading fluency, age-appropriate self-care, sports participation, and general self-esteem. If left untreated, several difficulties will arise for the child:
- He will struggle to keep up with peers due to poor reading and writing skills.
- Participation in sports that require good coordination, such as basketball, baseball, netball, tennis will be hampered.
- He will experience increased pressure and anxiety, as it is expected that most self care skills can be managed independently.
More Pointers on Mid-line Crossing…What are the key focus areas needed to develop the ability to cross the body’s mid-line?
- Body awareness: The information telling us about our body position, which is sent to our brain by the muscles and joints.
- Core stability and trunk rotation: Strong muscles of the trunk that help stabilize the body so the arms and legs can be moved with control.
- Hand dominance: The consistent use of one hand for different tasks so that fine movement control can develop.
- Bilateral integration skills (using both sides of the body at the same time).
- Planning and sequencing: The ability to follow multi-step instructions in a specific order to achieve a particular goal.
- Swap hands mid-way through a task when writing, drawing, painting or colouring.
- Use the left hand for activities on the left side of the body and right hand for activities on the right hand side.
- Rotate their trunk to the opposite side when reaching across the body (to avoid crossing the body’s mid-line).
- Have difficulty visually tracking an object from one side of the body to the other, such as following text when reading.
- Have poor pencil skills.
- Use different feet to kick a ball (mixed dominance).
- Have difficulty coordinating gross motor patterns – for instance, when crawling, making star-jumps, or skipping.
- Behaviour: The child may become angry or frustrated when engaging in fine motor activities due to less refined hand skills.
- Pencil based activities: The child may avoid these activities.
- Have less refined physical skills than their peers of the same age because of equalising use of both sides of the body.
- Noticing all of the details on a page when copying drawings or writing.
- Performing self-care tasks independently.
- Bilateral Integration Skills (using both sides of the body at the same time) – such as clapping their hands or waving both arms at the same time
- Daily Life Skills: Incorporate some mid-line crossing activities into your daily life skills – for instance, lay out socks and shoes so they are swapped to the opposite side of the body and the child is forced to cross the body’s mid-line to pull them on.
- Core Stability: Work on core stability and trunk rotation to encourage the physical movement of crossing the body’s mid-line – e.g, throwing a ball from the dominant side so the lower body stays still while the upper part of the trunk rotates.
- Craft: Threading beads, cutting and pasting, folding paper.
- Blocks and Percussion: Getting the child to bang blocks or percussion instruments together in their mid-line.
- Playing ‘Twister’ or ‘Simon Says’ and singing games like “Hokey Pokey”.
- Ribbons: Getting the child to make ribbon circles and patterns in front of their mid-line (use two hands together or one in each hand).
- Marching games using their arms and legs.
- Stickers: Placing stickers on one arm and encouraging the child to remove them with the opposite hand.
- Finger Puppets: Placing finger puppets on one hand and encouraging the child to remove the puppets with the opposite hand.