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Canthus
The canthus (: canthi, palpebral commissures) is either corner of the eye where the upper and lower eyelids meet. More specifically, the inner and outer canthi are, respectively, the medial and lateral ends/angles of the palpebral fissure. The bicanthal plane is the transversal plane linking both canthi and defines the upper boundary of the midface. Etymology The word ' is the Latinized form of the Ancient Greek ('), meaning 'corner of the eye'. Population distribution The eyes of East Asian and some Southeast Asian people tend to have the inner canthus veiled by the epicanthus. In the Caucasian or double eyelid, the inner corner tends to be exposed completely. Commissures * The ''lateral palpebral commissure'' (commissura palpebrarum lateralis; external canthus) is more acute than the medial, and the eyelids here lie in close contact with the bulb of the eye. * The ''medial palpebral commissure'' (commissura palpebrarum medialis; internal canthus) is prolonged for a s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epicanthic Fold
An epicanthic fold or epicanthus is a skin fold of the upper eyelid that covers the inner corner (medial canthus) of the Human eye, eye. However, variation occurs in the nature of this feature and the presence of "partial epicanthic folds" or "slight epicanthic folds" is noted in the relevant literature. Various factors influence whether epicanthic folds form, including ancestry, age, and certain medical conditions. The primary cause of the epicanthic fold is the hypertrophy of the preseptal portion of the orbicularis oculi muscle. Etymology ''Epicanthus'' means 'above the canthus', with epi-canthus being the Latinized form of the Ancient Greek : 'corner of the eye'. Classification Variation in the shape of the epicanthic fold has led to four types being recognised: * ''Epicanthus supraciliaris'' runs from the brow, curving downwards towards the lachrymal sac. * ''Epicanthus palpebralis'' begins above the upper Tarsus (eyelids), tarsus and extends to the inferior orbita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epicanthus
An epicanthic fold or epicanthus is a skin fold of the upper eyelid that covers the inner corner (medial canthus) of the eye. However, variation occurs in the nature of this feature and the presence of "partial epicanthic folds" or "slight epicanthic folds" is noted in the relevant literature. Various factors influence whether epicanthic folds form, including ancestry, age, and certain medical conditions. The primary cause of the epicanthic fold is the hypertrophy of the preseptal portion of the orbicularis oculi muscle. Etymology ''Epicanthus'' means 'above the canthus', with epi-canthus being the Latinized form of the Ancient Greek : 'corner of the eye'. Classification Variation in the shape of the epicanthic fold has led to four types being recognised: * ''Epicanthus supraciliaris'' runs from the brow, curving downwards towards the lachrymal sac. * ''Epicanthus palpebralis'' begins above the upper tarsus and extends to the inferior orbital rim. * ''Epicanthus tarsa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecanthus
Telecanthus, or dystopia canthorum, refers to increased distance between the inner corners of the eyelids (medial canthi), while the inter-pupillary distance is normal. This is in contrast to hypertelorism, in which the distance between the whole eyes is increased. Telecanthus and hypertelorism are each associated with multiple congenital disorders. The distance between the inner corners of the Eyelid, eyelids is called the intercanthal distance. In most people, the intercanthal distance is equal to the width of each eye (the distance between the inner and outer corners of each eye). The average interpupillary distance is 60–62 millimeters (mm), which corresponds to an intercanthal distance of approximately 30–31 mm. ''Traumatic telecanthus'' refers to telecanthus resulting from traumatic injury to the nasal-Orbit (anatomy), orbital-Ethmoid bone, ethmoid (NOE) complex. The diagnosis of traumatic telecanthus requires a measurement in excess of those normative values. The path ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canthotomy
Canthotomy (also called lateral canthotomy and canthotomy with cantholysis) is a surgical procedure where the lateral canthus, or corner, of the eye is cut to relieve the fluid pressure inside or behind the eye, known as intraocular pressure (IOC). The procedure is typically done in emergency situations when the intraocular pressure becomes too high, which can damage the optic nerve and lead to blindness if left untreated. The most common cause of elevated intraocular pressure is orbital compartment syndrome (OCS) caused by trauma, retrobulbar hemorrhage, infections, tumors, or prolonged hypoxemia. Absolute contraindications to canthotomy include globe rupture. Complications include bleeding, infections, cosmetic deformities, and functional impairment of eyelids. Lateral canthotomy further specifies that the lateral canthus is being cut. Canthotomy with cantholysis includes cutting the lateral palpebral ligament, also known as the canthal tendon. History The first case of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waardenburg Syndrome
Waardenburg syndrome is a group of rare genetic conditions characterised by at least some degree of congenital hearing loss and pigmentation deficiencies, which can include bright blue eyes (or Heterochromia iridum, one blue eye and one brown eye), a white forelock or patches of light skin. These basic features constitute type 2 of the condition; in type 1, there is also a wider gap between the inner corners of the eyes called telecanthus, telecanthus, or dystopia canthorum. In type 3, which is rare, the arms and hands are also malformed, with Camptodactyly, permanent finger contractures or fused fingers, while in type 4, the person also has Hirschsprung's disease. There also exist at least two types (2E and PCWH) that can result in central nervous system (CNS) symptoms such as developmental delay and muscle tone abnormalities. The syndrome is caused by mutations in any of several genes that affect the Cell division, division and Cell migration, migration of neural crest cells d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalometric Analysis
Cephalometric analysis is the clinical application of cephalometry. It is analysis of the dental and skeletal relationships of a human skull. It is frequently used by dentists, orthodontists, and oral and maxillofacial surgeons as a treatment planning tool. Two of the more popular methods of analysis used in orthodontology are the Steiner analysis (named after Cecil C. Steiner) and the Downs analysis (named after William B. Downs). There are other methods as well which are listed below. Cephalometric radiographs Cephalometric analysis depends on cephalometric radiography to study relationships between bony and soft tissue landmarks and can be used to diagnose facial growth abnormalities prior to treatment, in the middle of treatment to evaluate progress, or at the conclusion of treatment to ascertain that the goals of treatment have been met. A Cephalometric radiograph is a radiograph of the head taken in a Cephalometer (Cephalostat) that is a head-holding device introduc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyelid
An eyelid ( ) is a thin fold of skin that covers and protects an eye. The levator palpebrae superioris muscle retracts the eyelid, exposing the cornea to the outside, giving vision. This can be either voluntarily or involuntarily. "Palpebral" (and "blepharal") means relating to the eyelids. Its key function is to regularly spread the tears and other secretions on the eye surface to keep it moist, since the cornea must be continuously moist. They keep the eyes from drying out when asleep. Moreover, the blink reflex protects the eye from foreign bodies. A set of specialized hairs known as lashes grow from the upper and lower eyelid margins to further protect the eye from dust and debris. The appearance of the human upper eyelid often varies between different populations. The prevalence of an epicanthic fold covering the inner corner of the eye account for the majority of East Asian and Southeast Asian populations, and is also found in varying degrees among other populat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Eye
The human eye is a sensory organ in the visual system that reacts to light, visible light allowing eyesight. Other functions include maintaining the circadian rhythm, and Balance (ability), keeping balance. The eye can be considered as a living optics, optical device. It is approximately spherical in shape, with its outer layers, such as the outermost, white part of the eye (the sclera) and one of its inner layers (the pigmented choroid) keeping the eye essentially stray light, light tight except on the eye's optic axis. In order, along the optic axis, the optical components consist of a first lens (the cornea, cornea—the clear part of the eye) that accounts for most of the optical power of the eye and accomplishes most of the Focus (optics), focusing of light from the outside world; then an aperture (the pupil) in a Diaphragm (optics), diaphragm (the Iris (anatomy), iris—the coloured part of the eye) that controls the amount of light entering the interior of the eye; then an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nasal Bridge
The nasal bridge is the upper part of the nose, where the nasal bones and surrounding soft tissues provide structural support. While commonly discussed in human anatomy, nasal bridges exist in various forms across many vertebrates, particularly mammals. The shape, size, and function of the nasal bridge are influenced by evolutionary adaptations, playing a key role in Respiration (physiology), respiration, sense of smell, and thermoregulation. Anatomy Humans In humans, the nasal bridge is the elevated region of the human nose, nose between the eyes. It is primarily formed by the two small, oblong nasal bones, which meet at the midline to form the internasal suture. The nasal bridge extends from the nasal root, where the nose meets the forehead, to the lower edge of the nasal bones. Laterally, it reaches the inner canthi, the medial corners of the eyes, creating a saddle-shaped contour across the upper nose. The height and shape of the nasal bridge vary among individuals and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palpebral Fissure
The palpebral fissure is the elliptic space between the medial and lateral canthi of the two open eyelids. In simple terms, it is the opening between the eyelids. In adult humans, this measures about 10 mm vertically and 30 mm horizontally. Variations Congenital dysmorphisms It can be reduced (short, "narrow") in horizontal size by fetal alcohol syndrome and in Williams syndrome. The chromosomal conditions trisomy 9 and trisomy 21 (Down syndrome) can cause the palpebral fissures to be upslanted, whereas Marfan syndrome can cause a downslant. An increase in vertical height can be seen in genetic disorders such as cri-du-chat syndrome. Acquired The fissure may be increased in vertical height in Graves' disease, which is manifested as Dalrymple's sign. It is seen in disorders such as cri-du-chat syndrome. In animal studies using four times the therapeutic concentration of the ophthalmic solution latanoprost, the size of the palpebral fissure can be increased. The condi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Palpebral Raphe
The lateral palpebral raphe is a ligamentous band near the eye. Its existence is contentious, and many sources describe it as the continuation of nearby muscles. It is formed from the lateral ends of the orbicularis oculi muscle. It connects the orbicularis oculi muscle, the frontosphenoidal process of the zygomatic bone, and the tarsi of the eyelids. Structure The lateral palpebral raphe is formed from the lateral ends of the orbicularis oculi muscle. It may also be formed from the pretarsal muscles of the eyelids. It is attached to the margin of the frontosphenoidal process of the zygomatic bone. It passes towards the midline to the lateral commissure of the eyelids. Here, it divides into two slips, which are attached to the margins of the respective tarsi of the eyelids. The lateral palpebral ligament has a tensile strength of around 12 newtons. Relations The lateral palpebral raphe is a much weaker structure than the medial palpebral ligament on the other side of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fissure (anatomy)
In biological morphology and anatomy, a sulcus (: sulci) is a furrow or fissure (Latin ''fissura'', : ''fissurae''). It may be a groove, natural division, deep furrow, elongated cleft, or tear in the surface of a limb or an organ, most notably on the surface of the brain, but also in the lungs, certain muscles (including the heart), as well as in Osteology, bones, and elsewhere. Many sulci are the product of a surface fold or junction, such as in the Gingiva, gums, where they fold around the Cementoenamel junction, neck of the tooth. In invertebrate zoology, a sulcus is a fold, groove, or boundary, especially at the edges of sclerites or between Segmentation (biology), segments. In pollen, a grain that is grooved by a sulcus is termed sulcate. Examples in anatomy Liver *Ligamentum teres hepatis fissure *Ligamentum venosum fissure *Portal fissure, found in the under-surface of the liver *Transverse fissure of liver, found in the lower surface of the liver *Umbilical fissure, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
