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Secondary Palate
The secondary palate is an anatomical structure that divides the nasal cavity from the oral cavity in many vertebrates. In human embryology, it refers to that portion of the hard palate that is formed by the growth of the two palatine shelves medially and their mutual fusion in the midline. It forms the majority of the adult palate and meets the primary palate at the incisive foramen. Clinical significance Secondary palate development begins in the sixth week of pregnancy and can lead to cleft palate when development goes awry. There are three major mechanisms known to cause this failure: #Growth retardation — Palatal shelves do not grow enough to meet each other. #Mechanical obstruction — Improper mouth size, or abnormal anatomical structures in the embryonic mouth prevent fully grown shelves from meeting each other. #Midline epithelial dysfunction (MED) - The surface mucosa of embryonic shelves is impaired, which causes a failure of palatal fusion. Evolution T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palatine Raphe
The palatine raphe (also median palatine raphe) is a raphe of the oral cavity. It is a narrow, slight midline ridge extending anteroposteriorly across the palate, from the incisive papilla anteriorly to the palatine uvula posteriorly. Beneath the raphe, the submucosa is absent. Anatomy The palatine raphe is a midline tendinous band of the palate. Relations and attachments The raphe is a surface feature overlying - and indicating - the intermaxillary suture, and median palatine suture. The greater palatine foramen may be palpated on either side about half way between the palatine raphe, and the palatal gingival margin of the 2nd or 3rd upper molar tooth. The palatine raphe serves as an attachment for multiple muscles: the palatoglossus muscle The palatoglossal muscle is a muscle of the soft palate and an extrinsic muscle of the tongue. Its surface is covered by oral mucosa and forms the visible palatoglossal arch. Structure From its origin, it passes anteroinferio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pregnancy
Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs following sexual intercourse, vaginal intercourse, but can also occur through assisted reproductive technology procedures. A pregnancy may end in a Live birth (human), live birth, a miscarriage, an Abortion#Induced, induced abortion, or a stillbirth. Childbirth typically occurs around 40 weeks from the start of the Menstruation#Onset and frequency, last menstrual period (LMP), a span known as the Gestational age (obstetrics), ''gestational age''; this is just over nine months. Counting by Human fertilization#Fertilization age, ''fertilization age'', the length is about 38 weeks. Implantation (embryology), Implantation occurs on average 8–9 days after Human fertilization, fertilization. An ''embryo'' is the term for the deve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permian
The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the sixth and last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the Perm Governorate, region of Perm in Russia. The Permian witnessed the diversification of the two groups of amniotes, the synapsids and the Sauropsida, sauropsids (reptiles). The world at the time was dominated by the supercontinent Pangaea, which had formed due to the collision of Euramerica and Gondwana during the Carboniferous. Pangaea was surrounded by the superocean Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, which could better cope with these ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Therapsids
Therapsida is a clade comprising a major group of eupelycosaurian synapsids that includes mammals and their ancestors and close relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more underneath the body, resulting in a more "standing" quadrupedal posture, as opposed to the lower sprawling posture of many reptiles and amphibians. Therapsids evolved from earlier synapsids commonly called "pelycosaurs", specifically within the Sphenacodontia, more than 279.5 million years ago. They replaced the pelycosaurs as the dominant large land animals in the Guadalupian through to the Early Triassic. In the aftermath of the Permian–Triassic extinction event, therapsids declined in relative importance to the rapidly diversifying archosaurian sauropsids (pseudosuchians, dinosaurs and pterosaurs, etc.) during the Middle Triassic. The therapsids include the cynodonts, the group that gave rise to mammals (M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cynodonts
Cynodontia () is a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Mammals are cynodonts, as are their extinct ancestors and close relatives ( Mammaliaformes), having evolved from advanced probainognathian cynodonts during the Late Triassic. Non-mammalian cynodonts occupied a variety of ecological niches, both as carnivores and as herbivores. Following the emergence of mammals, most other cynodont lines went extinct, with the last known non-mammaliaform cynodont group, the Tritylodontidae, having its youngest records in the Early Cretaceous. Description Early cynodonts have many of the skeletal characteristics of mammals. The teeth were fully differentiated and the braincase bulged at the back of the head. Outside of some crown-group mammals (notably the therians), all cynodonts probably laid eggs. The temporal fenestrae were much larger than th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crocodilians
Crocodilia () is an order of semiaquatic, predatory reptiles that are known as crocodilians. They first appeared during the Late Cretaceous and are the closest living relatives of birds. Crocodilians are a type of crocodylomorph pseudosuchian, a subset of archosaurs that appeared about 235 million years ago and were the only survivors of the Triassic–Jurassic extinction event. While other crocodylomorph groups further survived the Cretaceous–Paleogene extinction event, notably sebecosuchians, only the crocodilians have survived into the Quaternary. The order includes the true crocodiles (family Crocodylidae), the alligators and caimans (family Alligatoridae), and the gharial and false gharial (family Gavialidae). Although the term "crocodiles" is sometimes used to refer to all of these families, the term "crocodilians" is less ambiguous. Extant crocodilians have flat heads with long snouts and tails that are compressed on the sides, with their eyes, ears, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Warm-blooded
Warm-blooded is a term referring to animal species whose bodies maintain a temperature higher than that of their environment. In particular, homeothermic species (including birds and mammals) maintain a stable body temperature by regulating metabolic processes. Other species have various degrees of thermoregulation. Because there are more than two categories of temperature control utilized by animals, the terms ''warm-blooded'' and '' cold-blooded'' have been deprecated in the scientific field. Terminology In general, warm-bloodedness refers to three separate categories of thermoregulation. * Endothermy is the ability of some creatures to control their body temperatures through internal means such as muscle shivering or increasing their metabolism. The opposite of endothermy is ectothermy. * Homeothermy maintains a stable internal body temperature regardless of external influence and temperatures. The stable internal temperature is often higher than the immediate environme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cleft Palate
A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate (the roof of the mouth) contains an opening into the nose. The term orofacial cleft refers to either condition or to both occurring together. These disorders can result in feeding problems, speech problems, hearing problems, and frequent ear infections. Less than half the time the condition is associated with other disorders. Cleft lip and palate are the result of tissues of the face not joining properly during development. As such, they are a type of birth defect. The cause is unknown in most cases. Risk factors include smoking during pregnancy, diabetes, obesity, an older mother, and certain medications (such as some used to treat seizures). Cleft lip and cleft palate can often be diagnosed during pregnancy with an ultrasound exam. A cleft lip or palate can be successfully treated with surge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Palate Development
The development of the secondary palate commences in the sixth week of human embryonic development. It is characterised by the formation of two palatal shelves on the maxillary prominences, the elevation of these shelves to a horizontal position, and then a process of palatal fusion between the horizontal shelves. The shelves will also fuse anteriorly upon the primary palate, with the incisive foramen being the landmark between the primary palate and secondary palate. This forms what is known as the roof of the mouth, or the hard palate. The formation and development of the secondary palate occurs through signalling molecules Sonic hedgehog, SHH, Bone morphogenetic protein 2, BMP-2, FGF-8, among others. Failure of the secondary palate to develop correctly may result in a cleft palate disorder. Formation of palatal shelves The formation of the vertical palatal shelves occurs during week 7 of embryological development, on the maxillary processes of the head of the embryo, lateral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nasal Cavity
The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal cavity is the uppermost part of the respiratory system and provides the nasal passage for inhaled air from the nostrils to the nasopharynx and rest of the respiratory tract. The paranasal sinuses surround and drain into the nasal cavity. Structure The term "nasal cavity" can refer to each of the two cavities of the nose, or to the two sides combined. The lateral wall of each nasal cavity mainly consists of the maxilla. However, there is a deficiency that is compensated for by the perpendicular plate of the palatine bone, the medial pterygoid plate, the labyrinth of ethmoid and the inferior concha. The paranasal sinuses are connected to the nasal cavity through small orifices called ostia. Most of these ostia communicat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Incisive Foramen
In the human mouth, the incisive foramen (also known as: "''anterior palatine foramen''", or "''nasopalatine foramen''") is the opening of the incisive canals on the hard palate immediately behind the incisor teeth. It gives passage to blood vessels and nerves. The incisive foramen is situated within the incisive fossa of the maxilla. The incisive foramen is used as an anatomical landmark for defining the severity of cleft lip and cleft palate. The incisive foramen exists in a variety of species. Structure The incisive foramen is a funnel-shaped opening in the bone of the oral hard palate representing the inferior termination of the incisive canal. An oral prominence - the incisive papilla - overlies the incisive fossa. The incisive foramen is situated immediately behind the incisor teeth, and in between the two premaxillae. Contents The incisive foramen allows for blood vessels and nerves to pass. These include: * the pterygopalatine nerves to the hard palate. * th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary Palate
Around the 5th week, the intermaxillary segment arises as a result of fusion of the two medial nasal processes and the frontonasal process within the embryo. The intermaxillary segment gives rise to the primary palate. The primary palate will form the premaxillary portion of the maxilla (anterior one-third of the final palate). This small portion is anterior to the incisive foramen and will contain the maxillary incisors. References Embryology {{developmental-biology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
