Final answer:
The loose connective tissue between cranial bones at birth is called fontanelles, providing flexibility for skull growth and childbirth, and typically closes by age 2.
Step-by-step explanation:
The cranial bones are separated by loose connective tissue at birth, which is known as fontanelles.
These fontanelles are expanded areas of fibrous connective tissue that separate the braincase bones of the skull prior to birth and during the first year after birth. They allow for continued growth of the skull after birth as the brain enlarges, providing flexibility during childbirth and rapid postnatal growth.
At birth, these areas enable the skull to change shape while the infant's head passes through the birth canal.
Eventually, as the child grows, the fontanelles decrease in size and disappear usually by age 2, while the skull bones remain separated at the sutures which contain dense fibrous connective tissue that unites the adjacent bones and allows for brain growth during childhood.