 | This article may be too technical for most readers to understand.(May 2012) |
In teratology, a proboscis is a blind-ended, tube-like structure, commonly located in the middle of the face. It is commonly seen in severe forms of holoprosencephaly that include cyclopia and is usually the result of abnormal development of the nose.
Proboscis formation is classified in four general types: holoprosencephalic proboscis, lateral nasal proboscis, supernumerary probosci, and disruptive proboscis.
A holoprosencephalic proboscis is found in holoprosencephaly (a condition in which the forebrain of the embryo fails to develop into two hemispheres as it should). In cyclopia or ethmocephaly, proboscis is an abnormally formed nose. In cyclopia, a single eye in the middle of the face is associated with arrhinia (absence of the nose) and usually with proboscis formation above the eye. In ethmocephaly, two separate hypoteloric eyes (eyes placed very close together) are associated with arrhinia and proboscis formation above the eye. In cebocephaly, no proboscis formation occurs, but a single-nostril nose is present.
A lateral proboscis, also known as proboscis lateralis or lateral nasal proboscis, is a tubular proboscis-like structure and represents incomplete formation of one side of the nose; it is found instead of a nostril. The olfactory bulb is usually rudimentary on the side involved in the malformation. The tear duct, nasal bone, nasal cavity, vomer (the small thin bone separating the left and right nasal passages), maxillary sinus, ethmoidal sinuses, and another nasal structure known as the cribriform plate cells are often missing on this side as well. Ocular hypertelorism (eyes set far apart) may be present. The proboscis lateralis is a rare nasal anomaly.
A supernumerary proboscis, or accessory proboscis, is found when both nostrils are formed and there is a proboscis in addition to it. Accessory proboscis arise from a supernumerary olfactory placode.
A disruptive proboscis occurs if an hamartoneoplastic lesion (benign growths such as are found in disorders like neofibromatosis and tubular sclerosis) arises in the prosencephalon (forebrain) of the embryo in its early stages of development.
Cranial nerves are the nerves that emerge directly from the brain, of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck, including the special senses of vision, taste, smell, and hearing.
A nostril is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbinates, whose function is to warm air on inhalation and remove moisture on exhalation. Fish do not breathe through noses, but they do have two small holes used for smelling, which can also be referred to as nostrils.
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Holoprosencephaly (HPE) is a cephalic disorder in which the prosencephalon fails to develop into two hemispheres, typically occurring between the 18th and 28th day of gestation. Normally, the forebrain is formed and the face begins to develop in the fifth and sixth weeks of human pregnancy. The condition also occurs in other species.
Ethmocephaly is a type of cephalic disorder caused by holoprosencephaly. Ethmocephaly is the least common facial anomaly. It consists of a proboscis separating narrow-set eyes with an absent nose and microphthalmia. Cebocephaly, another facial anomaly, is characterized by a small, flattened nose with a single nostril situated below incomplete or underdeveloped closely set eyes.
Rhinoplasty, commonly called nose job, medically called nasal reconstruction is a plastic surgery procedure for altering and reconstructing the nose. There are two types of plastic surgery used – reconstructive surgery that restores the form and functions of the nose and cosmetic surgery that changes the appearance of the nose. Reconstructive surgery seeks to resolve nasal injuries caused by various traumas including blunt, and penetrating trauma and trauma caused by blast injury. Reconstructive surgery can also treat birth defects, breathing problems, and failed primary rhinoplasties. Rhinoplasty may remove a bump, narrow nostril width, change the angle between the nose and the mouth, or address injuries, birth defects, or other problems that affect breathing, such as a deviated nasal septum or a sinus condition. Surgery only on the septum is called a septoplasty.
The ethmoid bone is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbits. The cubical bone is lightweight due to a spongy construction. The ethmoid bone is one of the bones that make up the orbit of the eye.
Cyclopia, also known as alobar holoprosencephaly, is the most extreme form of holoprosencephaly and is a congenital disorder characterized by the failure of the embryonic prosencephalon to properly divide the orbits of the eye into two cavities. Its incidence is 1 in 16,000 in born animals and 1 in 200 in miscarried fetuses.
Nasal polyps (NP) are noncancerous growths within the nose or sinuses. Symptoms include trouble breathing through the nose, loss of smell, decreased taste, post nasal drip, and a runny nose. The growths are sac-like, movable, and nontender, though face pain may occasionally occur. They typically occur in both nostrils in those who are affected. Complications may include sinusitis and broadening of the nose.
The paramesonephric ducts are paired ducts of the embryo that run down the lateral sides of the genital ridge and terminate at the sinus tubercle in the primitive urogenital sinus. In the female, they will develop to form the fallopian tubes, uterus, cervix, and the upper one-third of the vagina.
Otocephaly, also known as agnathia–otocephaly complex, is a very rare and lethal cephalic disorder characterized by the absence of the mandible (agnathia), with the ears fused together just below the chin (synotia). It is caused by a disruption to the development of the first branchial arch. It occurs in every 1 in 70,000 embryos.
In embryology, Carnegie stages are a standardized system of 23 stages used to provide a unified developmental chronology of the vertebrate embryo.
Arrhinia is the congenital partial or complete absence of the nose at birth. It is an extremely rare condition, with few reported cases in the history of modern medicine. It is generally classified as a craniofacial abnormality.
The nasal cartilages are structures within the nose that provide form and support to the nasal cavity. The nasal cartilages are made up of a flexible material called hyaline cartilage in the distal portion of the nose. There are five individual cartilages that make up the nasal cavity: septal nasal cartilage, lateral nasal cartilage, major alar cartilage, minor alar cartilage, and vomeronasal cartilage.
The human nose is the most protruding part of the face. It bears the nostrils and is the first organ of the respiratory system. It is also the principal organ in the olfactory system. The shape of the nose is determined by the nasal bones and the nasal cartilages, including the nasal septum which separates the nostrils and divides the nasal cavity into two. On average, the nose of a male is larger than that of a female.
A sinus is a sac or cavity in any organ or tissue, or an abnormal cavity or passage caused by the destruction of tissue. In common usage, "sinus" usually refers to the paranasal sinuses, which are air cavities in the cranial bones, especially those near the nose and connecting to it. Most individuals have four paired cavities located in the cranial bone or skull.
The respiratory system of the horse is the biological system by which a horse circulates air for the purpose of gaseous exchange.
Frontonasal dysplasia (FND) is a congenital malformation of the midface. For the diagnosis of FND, a patient should present at least two of the following characteristics: hypertelorism, a wide nasal root, vertical midline cleft of the nose and/or upper lip, cleft of the wings of the nose, malformed nasal tip, encephalocele or V-shaped hair pattern on the forehead. The cause of FND remains unknown. FND seems to be sporadic (random) and multiple environmental factors are suggested as possible causes for the syndrome. However, in some families multiple cases of FND were reported, which suggests a genetic cause of FND.
The nasal mucosa lines the nasal cavity. It is part of the respiratory mucosa, the mucous membrane lining the respiratory tract. The nasal mucosa is intimately adherent to the periosteum or perichondrium of the nasal conchae. It is continuous with the skin through the nostrils, and with the mucous membrane of the nasal part of the pharynx through the choanae. From the nasal cavity its continuity with the conjunctiva may be traced, through the nasolacrimal and lacrimal ducts; and with the frontal, ethmoidal, sphenoidal, and maxillary sinuses, through the several openings in the nasal meatuses. The mucous membrane is thickest, and most vascular, over the nasal conchae. It is also thick over the nasal septum where increased numbers of goblet cells produce a greater amount of nasal mucus. It is very thin in the meatuses on the floor of the nasal cavities, and in the various sinuses. It is one of the most commonly infected tissues in adults and children. Inflammation of this tissue may cause significant impairment of daily activities, with symptoms such as stuffy nose, headache, mouth breathing, etc.
The face and neck development of the human embryo refers to the development of the structures from the third to eighth week that give rise to the future head and neck. They consist of three layers, the ectoderm, mesoderm and endoderm, which form the mesenchyme, neural crest and neural placodes. The paraxial mesoderm forms structures named somites and somitomeres that contribute to the development of the floor of the brain and voluntary muscles of the craniofacial region. The lateral plate mesoderm consists of the laryngeal cartilages. The three tissue layers give rise to the pharyngeal apparatus, formed by six pairs of pharyngeal arches, a set of pharyngeal pouches and pharyngeal grooves, which are the most typical feature in development of the head and neck. The formation of each region of the face and neck is due to the migration of the neural crest cells which come from the ectoderm. These cells determine the future structure to develop in each pharyngeal arch. Eventually, they also form the neurectoderm, which forms the forebrain, midbrain and hindbrain, cartilage, bone, dentin, tendon, dermis, pia mater and arachnoid mater, sensory neurons, and glandular stroma.