What is “crossing the midline”?
By the age of 3 or 4 years old, a child should have mastered the bilateral skill (using both sides of the body together) called “crossing the midline”. This is the ability to move one hand, foot, or eye into the space of the other hand, foot or eye. We cross midline when we scratch an elbow, cross our ankles, and read left to right. Crossing the midline of your body helps build pathways in the brain and is an important prerequisite skill required for the appropriate development of various motor and cognitive skills. Children who have difficultly crossing the body’s midline often have trouble with skills such as reading, writing, completing self care skills and participating in sports & physical activities. These skills require a type of coordination that comes from experience with “cross-lateral motion,” which is movement involving the left arm and right leg, or the right arm and left leg at the same time.
Establishing a “worker hand” and a “helper hand” is a sign that the brain is maturating and lateralization is occurring, and is strongly correlated with the ability to cross the midline. Both sides of the brain need to talk to each other for the “worker hand” and the “helper hand” to work together and compliment each other. Coordinating both sides of the body can be difficult for the child who avoids crossing midline. Often, these children have not yet established a hand preference, sometimes using their left and sometimes using their right to draw, color, write, eat, and throw.
Affects on children who do not develop the bilateral skill:
Furthermore, when a child has difficulty crossing midline, it can affect his/her ability to read. While the child is moving his/her eyes from left to right across the page, the eyes will stop at midline to blink and refocus; however, when this happens, the child will very frequently lose his/her place on the line and become confused as to where they left off. It also affects handwriting, as diagonal lines cross the midline, and the child may need to stop in the middle of the page to switch hands when writing from left to right. Many self care and daily living skills require crossing midline. For example, perfecting the skill of putting socks or shoes on requires one hand to cross over to the other side of the body.
Children who have difficulty crossing midline may appear ambidextrous because they are often observed using both hands, but they actually have a hidden neuroprocessing issue. Both sides of their brains are not communicating, resulting in decreased coordination, decreased motor control of movements and difficulties achieving higher level skills. Often, these children end up with two unskilled hands.
Activities to help develop the ability to cross the midline:
To help develop efficient crossing of the midline, provide children with a variety of two-handed (bilateral) activities. Try some of the below activities to help build more pathways in the brain and to develop the ability to cross the midline, improve coordination, and improve overall functional performance on a daily basis.
Right brain/left brain teasers-
a. Pop bubbles with only one hand (they will have to reach across their body to pop the bubbles floating on the opposite side).
b. Reach for bean bags, balls, stuffed animals, or other objects across midline, then throwing at a target.
c. Draw large figure eights (the infinity sign or an 8 turned on its side) on paper, on the floor with a finger, in the air with a finger, or drive a matchbox car around a figure eight pattern.
d. Let the child play with sand, scooping sand from one side of the body and putting it into a bucket on the opposite side of the body without switching hands.
e. Let the child pretend to drive a car with a ball in his/her hands to use as a steering wheel and encourage the crossing of his/her arms as he/she turns the ‘steering wheel’ OR to make this similar in style to most of the others—pretend to drive a car with a ball in both hands to use as a steering wheel and cross both arms while turning the “steering wheel”.
f. Play flashlight tag. In a dimmed room, lie on your backs and have the child follow your flashlight beam projected on the wall with his own flashlight.
g. Touch the opposite elbow and knee.
h. Cross one foot over the other while walking sideways.
i. Do “grapevine” walks.
j. Knee slap walk- Walk around raising each knee while touching/slapping it with the opposite hand (or elbow). Change it to a skip while touching the opposite knee as it comes up.
k. Windmill-stand with feet spread apart and arms extended out to the sides. Bend over at waist and tap right hand to left foot. Stand back up and then bend and tap left hand to right foot.
l. Point your left finger out and put your right thumb up. Switch them, and switch, and switch, and switch…
m. Hold your nose, then cross the other hand over and grab your opposite ear. Slap your thighs and switch your hands…switch, slap, switch, slap…
n. Write your name in the air while rotating your foot in a circle clockwise.
o. Wash the car and make sure the arms cross midline while scrubbing.