anterior fontanelle define
A fontanelle (or fontanel) (colloquially, soft spot) is an anatomical feature of the infant human skull comprising any of the soft membranous gaps (sutures) between the cranial bones that make up the calvaria of a fetus or an infant. The ossification of the bones of the skull causes the anterior fontanelle to close over by 9 to 18 months. The sphenoidal and posterior fontanelles close during the first few months of life. The closures eventually form the sutures of the neurocranium. The diagnosis of an abnormal fontanel requires an understanding of the wide variation of normal. At birth, an infant has six fontanels. The anterior fontanel is the largest and most important for clinical evaluation. The average size of the anterior fontanel is 2.1 cm, and the median time of closure is 13.8 months. TRENDING NOW. 1  nonnuclear 'Not nuclear'. 2  armada 'A fleet of warships'. 3  volunteer 'Someone who does something without being forced to do it'. 4  operationalize Bannon was removed from the National Security Council.  filibuster 'An effort to prevent action in a legislature'. Medical Definition of fontanel. : a membrane-covered opening in bone or between bones; specifically : any of the spaces closed by membranous structures between the uncompleted angles of the parietal bones and the neighboring bones of a fetal or young skull. Quick Answer. The function of fontanels is to allow a baby's brain to grow during the first year of life and for the baby's head to pass through the birth canal. Fontanels are the soft areas between the bones of the skull. Babies have two fontanels: the anterior and the posterior. The posterior fontanel closes within the first few months of life, while the anterior one closes much later. If the fontanels close too early, the baby's brain cannot grow in that direction and will grow in another direction, causing misshaping of the head. Medical Definition of anterior fontanel. : the fontanel occurring at the meeting point of the coronal and sagittal sutures. Anterior fontanelle. The anterior fontanelle (bregmatic fontanelle, frontal fontanelle) is the largest fontanelle, and is placed at the junction of the sagittal suture, coronal suture, and frontal suture; it is lozenge-shaped, and measures about 4 cm in its antero-posterior and 2.5 cm in its transverse diameter. The posterior fontanelle generally closes 2 to 3 months after birth; The sphenoidal fontanelle is the next to close around 6 months after birth; The mastoid fontanelle closes next from 6 to 18 months after birth; and. The anterior fontanelle is generally the last to close between 18–24 months.
It is the largest fontanelle, and is placed at the junction of the sagittal suture, coronal suture, and frontal suture.