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Nasal Placode
In embryology, the nasal placode (or olfactory placode) gives rise to the olfactory epithelium of the human nose, nose. Two nasal Neurogenic placode, placodes arise as thickened ectoderm from the frontonasal process. They give rise to the human nose, nose, the philtrum of the upper lip, and the primary palate. Development During the fifth week of human embryonic development, the placodes increase in size. In the sixth week of development the centre of each placode invagination, grows inwards to form the two nasal pits. The invaginations will give rise to the olfactory epithelium that lines the roof of the nasal cavity. The nasal pits are oval shaped and they leave a raised margin which is divided into a medial nasal process and a lateral nasal process. The medial and lateral nasal process of each placode gives rise to the nose, the philtrum of the upper lip and the primary palate. References External links * https://web.archive.org/web/20130509194720/http://embryology.me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olfactory System
The olfactory system, is the sensory nervous system, sensory system used for the sense of smell (olfaction). Olfaction is one of the special senses directly associated with specific organs. Most mammals and reptiles have a main olfactory system and an accessory olfactory system. The main olfactory system detects airborne substances, while the accessory system senses fluid-phase stimuli. The senses of smell and taste (gustatory system) are often referred to together as the chemosensory system, because they both give the brain information about the chemical composition of objects through a process called transduction (physiology), transduction. Structure Peripheral The peripheral olfactory system consists mainly of the nostrils, ethmoid bone, nasal cavity, and the olfactory epithelium (layers of thin tissue covered in mucus that line the nasal cavity). The primary components of the layers of epithelial tissue are the mucous membranes, olfactory glands, olfactory receptor neurons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Embryonic Development
Human embryonic development or human embryogenesis is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, the development of the human body entails growth from a one-celled zygote to an adult human being. Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell (ovum). The genetic material of the sperm and egg then combine to form the single cell zygote and the germinal stage of development commences. Human embryonic development covers the first eight weeks of development, which have 23 stages, called Carnegie stages. At the beginning of the ninth week, the embryo is termed a fetus (spelled "foetus" in British English). In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs. Human embryology is the study o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palate
The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly separated. The palate is divided into two parts, the anterior, bony hard palate and the posterior, fleshy soft palate (or velum). Structure Innervation The maxillary nerve branch of the trigeminal nerve supplies sensory innervation to the palate. Development The hard palate forms before birth. Variation If the fusion is incomplete, a cleft palate results. Function in humans When functioning in conjunction with other parts of the mouth, the palate produces certain sounds, particularly velar, palatal, palatalized, postalveolar, alveolopalatal, and uvular consonants. History Etymology The English synonyms palate and palatum, and also the related adjective palatine (as in palatine bone), are all from the Latin ''palatum' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nose
A nose is a sensory organ and respiratory structure in vertebrates. It consists of a nasal cavity inside the head, and an external nose on the face. The external nose houses the nostrils, or nares, a pair of tubes providing airflow through the nose for Respiration (physiology), respiration. Where the nostrils pass through the nasal cavity they widen, are known as nasal fossae, and contain nasal concha, turbinates and olfactory mucosa. The nasal cavity also connects to the paranasal sinuses (dead-end air cavities for pressure buffering and humidification). From the nasal cavity, the nostrils continue into the pharynx, a switch track valve connecting the respiratory system, respiratory and digestive systems. In humans, the nose is located centrally on the face and serves as an alternative respiratory passage especially during suckling for infants. The protruding nose that is completely separate from the mouth part is a characteristic found only in theria, therian mammals. It has b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Nasal Process
The frontonasal process, or frontonasal prominence is one of the five swellings that develop to form the face. The frontonasal process is unpaired, and the others are the paired maxillary prominences, and the paired mandibular prominences. During the fourth week of embryonic development, an area of thickened ectoderm develops, on each side of the frontonasal process called the nasal placodes or olfactory placodes, and appear immediately under the forebrain. By invagination these areas are converted into two nasal pits, which indent the frontonasal prominence and divide it into medial and lateral nasal processes. Nasal processes The medial nasal process (nasomedial) on the inner side of each nasal pit merge into the intermaxillary segment and form the upper lip, crest, and tip of the nose. The medial nasal processes merge with the maxillary prominences. The lateral nasal process from each side merge to form the alae of the nose. Clinical significance Failure to fuse can cause a ... [...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] |
Invagination
Invagination is the process of a surface folding in on itself to form a cavity, pouch or tube. In developmental biology, invagination of Epithelium, epithelial sheets occurs in many contexts during Animal embryonic development, embryonic development. Invagination is critical for making the Archenteron, primitive gut during gastrulation in many organisms, forming the neural tube in Vertebrate, vertebrates, and in the morphogenesis of countless Organ (biology), organs and sensory structures. Models of invagination that have been most thoroughly studied include the ventral furrow in Drosophila melanogaster, ''Drosophila'' ''melanogaster'', neural tube formation, and gastrulation in many marine organisms. The cellular mechanisms of invagination vary from one context to another but at their core they involve changing the mechanics of one side of a sheet of cells such that this pressure induces a bend in the tissue. The term, originally used in embryology, has been adopted in other disc ... [...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] |
Olfactory Epithelium
The olfactory epithelium is a specialized epithelium, epithelial tissue inside the nasal cavity that is involved in olfaction, smell. In humans, it measures and lies on the roof of the nasal cavity about above and behind the nostrils. The olfactory epithelium is the part of the olfactory system directly responsible for detecting odors. Structure Olfactory epithelium consists of four distinct cell types: * Olfactory receptor neuron, Olfactory sensory neurons * Supporting cells * Basal cells * Brush cells Olfactory sensory neurons The olfactory receptor neurons are sensory neurons of the olfactory epithelium. They are bipolar neurons and their apical poles express odorant receptors on cilium, non-motile cilia at the ends of the dendritic knob, which extend out into the airspace to interact with odorants. Odorant receptors bind odorants in the airspace, which are made soluble by the serous secretions from olfactory glands located in the lamina propria of the mucosa.Ross, MH, '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philtrum
The philtrum (, from Ancient Greek , lit. 'love charm') or medial cleft is a vertical indentation in the middle area of the upper lip, common to therian mammals, extending in humans from the nasal septum to the tubercle of the upper lip. Together with a glandular rhinarium and slit-like nostrils, it is believed to constitute the primitive condition for at least therian mammals. Monotremes lack a philtrum, though this could be due to the specialised, beak-like jaws in living species. Function In most mammals, the philtrum is a narrow groove that may carry dissolved odorants from the rhinarium or nose pad to the vomeronasal organ via ducts inside the mouth. For humans and most primates, the philtrum survives only as a vestigial medial depression between the nose and upper lip. The human philtrum, bordered by a pair of ridges known as the ''philtral columns'', is also known as the ''infranasal depression'', but has no apparent function. That may be because most higher pri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frontonasal Process
The frontonasal process, or frontonasal prominence is one of the five swellings that develop to form the face. The frontonasal process is unpaired, and the others are the paired maxillary prominences, and the paired mandibular prominences. During the fourth week of embryonic development, an area of thickened ectoderm develops, on each side of the frontonasal process called the nasal placodes or olfactory placodes, and appear immediately under the forebrain. By invagination these areas are converted into two nasal pits, which indent the frontonasal prominence and divide it into medial and lateral nasal processes. Nasal processes The medial nasal process (nasomedial) on the inner side of each nasal pit merge into the intermaxillary segment and form the upper lip, crest, and tip of the nose. The medial nasal processes merge with the maxillary prominences. The lateral nasal process from each side merge to form the alae of the nose. Clinical significance Failure to fuse can cause a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
