The 2 carotid arteries on each side of the neck are the most important because they supply blood to the parts of the brain that are involved in thinking, movement, sensation and speech. The other 2 arteries that bring blood to the brain, called the vertebral arteries, supply the brainstem.
The vast majority of babies sprout their first tooth when they're between 4 and 7 months old. An early developer may get his first white cap as early as 3 months, while a late bloomer may have to wait until he's a year old or more.y age 3, your child should have a full set of 20 baby teeth, and they shouldn't start to fall out until his permanent teeth are ready to start coming in â around age 6.
Babies' teeth begin to develop before they are born, but in most cases don't come through until they're between 6 and 12 months old. Most children have a full set of 20 milk or baby teeth by the time they're three years old. When they reach five or six, these teeth will start to fall out, making way for adult teeth.