They don't hold you upright, more like sideways...
It is appropriate to hold a baby upright when they have good head control, typically around 4-6 months of age. This helps them strengthen their neck muscles and develop balance.
Voluntary muscles move bones and hold your skeleton upright. hope you know now... :D
No, it is not safe to sit a newborn upright as their neck muscles are not strong enough to support their head. It is recommended to wait until the baby can hold their head up on their own, typically around 4-6 months of age, before sitting them upright.
Never, you always have working muscles. Eg: your core muscles work to keep you standing/upright.
Parents should hold their baby upright with their head supported and their back straight to promote proper development and comfort. This position helps strengthen the baby's neck and back muscles while also providing a sense of security and comfort.
the stem
Piloerector muscles
The gluteus muscles are used when walking. They support the upper body in an upright posture.
To safely transition your newborn from sitting to an upright position, start by supporting their head and neck until they have developed enough strength to hold it up on their own. Gradually increase the time they spend in an upright position to allow their muscles to strengthen. Always supervise your baby during this transition to prevent any accidents or falls.
The muscles are called arrector pili and they pull the hair upright for both of those reasons and a few others.. let me know if you want to know more :)
Pectoralis Major
There aren't any antigravity muscles in the human body. But as long as you're upright there are plenty of muscles that are working against gravity.