- Human physiological development
- Egg, sperm, and fertilization
- Early embryogenesis - Cleavage, blastulation, gastrulation, and neurulation
- Germ layer derivatives
- Major motor milestones
- Motor development
- Neonatal reflexes
- Physical development in adolescence
- Brain changes during adolescence
Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Brooke Miller.
Want to join the conversation?
- What do you mean when you say that muscles "develop"?
Do new muscles form as a child matures?
Or are children born with all of their muscles and more myocytes form as they mature (just like more myocytes form as an adult works out)?
Or are the sensory/motor neural connections weak? (How do you strengthen a neural connection, anyhow?)(2 votes)
- [Instructor] I want to talk about motor development as it relates to the nature-nurture debate. And the nature part of this debate is spoken about in terms of maturation. Which refers to genetic factors as well as anatomical and neurophysiological traits that drive motor development. And we know that motor skills are driven by internal biological factors for a number of reasons. For example, we know that identical twins typically begin to walk on the same day. Much closer than non-related infants of the same age. Other evidence for this is the fact that children all over the world tend to develop skills at the same time and in the same order. We also know that blind children tend to show the same timing and progression, and they obviously could not have learned this through observation and imitation of those around them. And this actually makes a lot of sense when you think about it. As children grow, their brains and their muscles grow as well. And before areas of the brain like the cerebellum develop and before the muscles are strong enough, infants simply aren't developed enough to allow for things like crawling or walking. They can't sit up or crawl or walk without that biological support. No matter how much practice or experience a parent tries to give. And I want to point out that the same is true for the muscles involved in bladder control and bowel control. Toilet training simply can't happen before those muscles are developed. It doesn't matter what rewards or punishments parents try to give. But the environment can still play an important role in the development and motor skills. How much space and time a child has to practice these skills can have an affect on development. Culture can also have an influence on development. For example, these days doctors typically recommend that infants sleep on their backs instead of on their stomachs. And this is great advice. That small change in how children sleep significantly decreased the chances of sudden infant death syndrome or SIDS. However, we also now know that the sleeping position tends to be correlated with children crawling at a somewhat later time. And of course, this really doesn't matter in the scheme of things. And sleeping position doesn't affect the development of later motor skills, like walking. But it is an interesting way that our culture winds up influencing motor development. We also know that wearing diapers can lead to children walking slightly later. But to me, this seems like a small price to pay for the convenience. I suppose you could follow your child around all the time or maybe cover your entire home in plastic, but that sounds like a lot more work for not a lot of gain. There are also a couple of patterns that you should keep in mind when you think about motor development. The first one is that we can break motor skills down into two main types: gross motor skills and fine motor skills. Gross motor skills are skills that involve larger muscles, our arms and our legs. While fine motor skills refer to movements that involve smaller muscles, like our fingers. So gross motor skills would involve things like sitting up and walking. While fine motor skills would be things like cutting with scissors or coloring a picture. And as you might expect, large muscles like those in our arms and legs tend to develop before small muscles like the ones in our fingers. Which explains why we can do things like sit up and walk before we can hold a marker and color a picture. Development also tends to move from the head to the toes, which is why babies are able to lift their heads before they can crawl. And maybe you're a parent, and you're wondering if there is anything that you can do to speed up these motor milestones. And the answer is, kind of. As we mentioned earlier, certain actions can't physically be done until the brain and the muscles are ready for them. But, once that child starts a behavior, it is good to provide a lot of space and time that will allow the child to practice. Also, enriched environments with different kinds of toys can allow for increased motor exploration, which seems to speed up the rate at which certain milestones might be achieved. That said, I do want to stress that the research indicates that it doesn't necessarily matter and that children who are late in developing some skills might be faster in attaining others. And I also want to take a moment to point out, any parents who may be watching this, that they might want to appreciate the time before their children develop motor milestones rather than trying to speed them up. Because once children start moving independently, they don't really ever stop. So enjoy the time that you have when you can put an infant down and look away for a moment while still being confident that the child will be in the same spot when you turn back around.