fontanelles

泉門

WordNet

1. any membranous gap between the bones of the cranium in an infant or fetus (同)fontanel, soft_spot

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/12/25 12:56:46」(JST)

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This article is about the human anatomical feature. For other uses, see Fontanelle (disambiguation).

"Soft spot" redirects here. For the Clem Snide album, see Soft Spot.

Fontanelle
The skull at birth, showing the anterior and posterior fontanelles.
The skull at birth, showing the lateral fontanelles.
Latin	fonticuli cranii

A fontanelle (or fontanel) is an anatomical feature on an infant's skull.

Anatomy

Fontanelles are soft spots on a baby's head which, during birth, enable the bony plates of the skull to flex, allowing the child's head to pass through the birth canal. The ossification of the bones of the skull causes the anterior fontanelle to close over by 18 to 24 months. The sphenoidal and posterior fontanelles close during the first few months of life. The closures eventually form the sutures of the neurocranium. Other than the anterior and posterior fontanelles, the mastoid fontanelle and the sphenoidal fontanelle are also significant.

The skull of a newborn consists of five main bones: two frontal bones, two parietal bones, and one occipital bone. These are joined by fibrous sutures, which allow movement that facilitates childbirth and brain growth.

• At birth, the skull features a small posterior fontanelle, an open area covered by a tough membrane, where the two parietal bones adjoin the occipital bone (at the lambda). This fontanelle usually closes during the first two to three months of an infant's life. This is called intramembranous ossification. The mesenchymal connective tissue turns into bone tissue.

• The much larger, diamond-shaped anterior fontanelle where the two frontal and two parietal bones join generally remains open until the child is about two years of age, however, in cleidocranial dysostosis it is often late in closing or may never close. Examination of an infant includes palpating the anterior fontanelle.

• Two smaller fontanelles are located on each side of the head, more anteriorly the sphenoidal or anterolateral fontanelle (between the sphenoid, parietal, temporal, and frontal bones) and more posteriorly the mastoid or posterolateral fontanelle (between the temporal, occipital, and parietal bones).

Clinical significance

A sunken (also called "depressed") fontanelle indicates dehydration, whereas a very tense or bulging anterior fontanelle indicates raised intracranial pressure.

The fontanelle may pulsate, and although the precise cause of this is not known, it is perfectly normal and seems to echo the heartbeat, perhaps via the arterial pulse within the brain vasculature, or in the meninges. This pulsating action is how the soft spot got its name - fontanelle means "little fountain."

Parents may worry that their infant may be more prone to injury at the fontanelles. In fact, although they may colloquially be called "soft-spots", the membrane covering the fontanelles is extremely tough and difficult to penetrate.

Fontanelles allow the infant brain to be imaged using ultrasonography. Once they are closed, most of the brain is inaccessible to ultrasound imaging, because the bony skull presents an acoustic barrier.

In cleidocranial dysostosis the skull fontanelle may be enlarged, and may be slow to close or may never close.

In dogs

One of the more serious problems that can affect canines is known as an "open fontanelle," which occurs when the skull bones at the top of the head fail to close. The problem is often found in conjunction with hydrocephalus, which is a condition in which too much fluid is found within and around the brain, placing pressure on the brain and surrounding tissues. Often the head will appear dome-shaped, and the open fontanelle is noticeable as a "soft spot" on the top of the dog's head. The fluid-filled spaces within the brain, known as ventricles, also become swollen. The increased pressure damages or prevents the development of brain tissue.

Not all open fontanelles are connected with hydrocephalus. In many young dogs the skull bones are not fused at birth, but instead will close slowly over a three- to six-month period. Occasionally these bones fail to close, but the dog is still healthy. In these cases, however, the dog's owners need to be very careful, since any injury or bumps to the animal's head could cause significant brain damage, as well as conditions like epilepsy.

Additional images

• Fontanelle.

• Anterior fontanelle.

• Cranial sutures shown from top of head.

References

UpToDate Contents

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• 1. 小児における身体的診察：HEENT the pediatric physical examination heent
• 2. 新生児の評価 assessment of the newborn infant
• 3. 頭蓋骨縫合早期癒合症の概要 overview of craniosynostosis
• 4. 幼児および小児における巨頭症：病因および評価 macrocephaly in infants and children etiology and evaluation
• 5. ウイルス性髄膜炎：小児における臨床的特徴および診断 viral meningitis clinical features and diagnosis in children

English Journal

• ["The two fontanelles sign": A new clinical sign for quality control in fetal head position diagnosis?]

• Dupuis O1, Brocco B2, Decullier E1, Coulange-Benevise L1.
• Journal de gynecologie, obstetrique et biologie de la reproduction.J Gynecol Obstet Biol Reprod (Paris).2016 Feb 10. pii: S0368-2315(15)00384-1. doi: 10.1016/j.jgyn.2015.12.007. [Epub ahead of print]
• OBJECTIVES: Determine the frequency at which palpation of two fontanelles is possible, in order to describe a new clinical diagnosis approach: "the two fontanelles sign".MATERIALS AND METHODS: Descriptive study established in the obstetric and gynecology department at Lyon-Sud university hospital be
• PMID 26874667

• Frontal Bone Insufficiency in Gsk3β Mutant Mice.

• Szabo-Rogers H1, Yakob W1, Liu KJ1.
• PloS one.PLoS One.2016 Feb 17;11(2):e0149604. doi: 10.1371/journal.pone.0149604. eCollection 2016.
• The development of the mammalian skull is a complex process that requires multiple tissue interactions and a balance of growth and differentiation. Disrupting this balance can lead to changes in the shape and size of skull bones, which can have serious clinical implications. For example, insufficien
• PMID 26886780

• An exceptionally preserved Late Devonian actinopterygian provides a new model for primitive cranial anatomy in ray-finned fishes.

• Giles S1, Darras L2, Clément G3, Blieck A4, Friedman M5.
• Proceedings. Biological sciences / The Royal Society.Proc Biol Sci.2015 Oct 7;282(1816):20151485. doi: 10.1098/rspb.2015.1485.
• Actinopterygians (ray-finned fishes) are the most diverse living osteichthyan (bony vertebrate) group, with a rich fossil record. However, details of their earliest history during the middle Palaeozoic (Devonian) 'Age of Fishes' remains sketchy. This stems from an uneven understanding of anatomy in
• PMID 26423841

Japanese Journal

• Large fontanelles are a shared feature of haploinsufficiency of RUNX2 and its co-activator CBFB

• Congenital anomalies 44(4), 225-229, 2004-12-01
• NAID 10027383968

• 胎児・新生児中枢神経疾患の超音波診断　　経ちつ超音波法および三次元超音波法による胎児中枢神経系の診断

• Neurosonology:神経超音波医学 13(1), 5-11, 2000
• NAID 130001742484

• 牛の単眼症3例

• 日本獣医師会雑誌 52(10), 644-647, 1999
• NAID 130003848236

Related Links

• Fontanelles | Define Fontanelles at Dictionary.com

Fontanelles definition, one of the spaces, covered by membrane, between the bones of the fetal or young skull. See more. Thesaurus Translate Puzzles & Games Reference Word of the Day Blog Slideshows Apps by Dictionary ...

• The Fontanelles | Facebook

The Fontanelles. 731 likes · 12 talking about this. We love you and want to be with you.

Related Pictures

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★リンクテーブル★

リンク元

「泉門」

「泉門」

　　[★]

英

fontanelle, fontanelles

ラ

fonticulus, fonticuli cranii

同

頭蓋泉門

関

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泉門

• 大泉門
• 小泉門
• 前側頭泉門 sphenoidal fontanelle
• 後側頭泉門 mastoid fontanelle