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Vertex (anatomy)
In arthropod and vertebrate anatomy, the vertex (or ''cranial vertex'') is the highest point of the head. In humans, the vertex is formed by four bones of the skull: the frontal bone, the two parietal bones, and the occipital bone. These bones are connected by the coronal suture between the frontal and parietal bones, the sagittal suture between the two parietal bones, and the lambdoid suture between the parietal and occipital bones. ''Vertex baldness'' refers to a form of male pattern baldness in which the baldness is limited to the vertex, resembling a tonsure. In childbirth, ''vertex birth'' refers to the common head-first presentation of the baby, as opposed to the buttocks-first position of a breech birth. In entomology, the color and shape of an insect's vertex and the structures arising from it are commonly used in identifying species. See also *Calvaria (skull) *Crown (anatomy) The crown is the top portion of the head behind the vertex. The anatomy of the crown varies ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arthropod cuticle, cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. Arthropods are bilaterally symmetrical and their body possesses an exoskeleton, external skeleton. In order to keep growing, they must go through stages of moulting, a process by which they shed their exoskeleton to reveal a new one. Some species have wings. They are an extremely diverse group, with up to 10 million species. The haemocoel, an arthropod's internal cavity, through which its haemolymph – analogue of blood – circulates, accommodates its interior Organ (anatomy), organs; it has an open circulatory system. Like their exteriors, the internal or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Male Pattern Baldness
Pattern hair loss (also known as androgenetic alopecia (AGA)) is a hair loss condition that primarily affects the top and front of the scalp. In male-pattern hair loss (MPHL), the hair loss typically presents itself as either a receding front hairline, loss of hair on the crown (vertex) of the scalp, or a combination of both. Female-pattern hair loss (FPHL) typically presents as a diffuse thinning of the hair across the entire scalp. Male pattern hair loss seems to be due to a combination of oxidative stress, the microbiome of the scalp, genetics, and circulating androgens; particularly dihydrotestosterone (DHT). Men with early onset androgenic alopecia (before the age of 35) have been deemed as the male phenotypic equivalent for polycystic ovary syndrome (PCOS). As an early clinical expression of insulin resistance and metabolic syndrome, AGA is related to being an increased risk factor for cardiovascular diseases, glucose metabolism disorders, type 2 diabetes, and enlargement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calvaria (skull)
The calvaria is the top part of the skull. It is the upper part of the neurocranium and covers the cranial cavity containing the brain. It forms the main component of the skull roof. The calvaria is made up of the superior portions of the frontal bone, occipital bone, and parietal bones. In the human skull, the sutures between the bones normally remain flexible during the first few years of postnatal development, and fontanelles are palpable. Premature complete ossification of these sutures is called craniosynostosis. In Latin, the word ''calvaria'' is used as a feminine noun with plural ''calvariae''; however, many medical texts list the word as ''calvarium'', a neuter Latin noun with plural ''calvaria''. Structure The outer surface of the skull possesses a number of landmarks. The point at which the frontal bone and the two parietal bones meet is known as "Bregma". The point at which the two parietal bones and the occipital bone meet is known as "Lambda". Not only do t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entomology
Entomology () is the science, scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such as arachnids, myriapods, and crustaceans. This wider meaning may still be encountered in informal use. Like several of the other fields that are categorized within zoology, entomology is a taxon-based category; any form of scientific study in which there is a focus on insect-related inquiries is, by definition, entomology. Entomology therefore overlaps with a cross-section of topics as diverse as molecular genetics, behavior, neuroscience, biomechanics, biochemistry, systematics, physiology, developmental biology, ecology, morphology (biology), morphology, and paleontology. Over 1.3 million insect species have been described, more than two-thirds of all known species. Some insect species date back to around 400 million years ago. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breech Birth
A breech birth is when a baby is born bottom first instead of head first, as is normal. Around 3–5% of pregnant women at term (37–40 weeks pregnant) have a breech baby. Due to their higher than average rate of possible complications for the baby, breech births are generally considered higher risk. Breech births also occur in many other mammals such as dogs and horses, see veterinary obstetrics. Most babies in the breech position are delivered via caesarean section because it is seen as safer than being born vaginally. Doctors and midwives in the developing world often lack many of the skills required to safely assist women giving birth to a breech baby vaginally. Also, delivering all breech babies by caesarean section in developing countries is difficult to implement as there are not always resources available to provide this service. OB-GYNs do not recommend home births if a breech birth is expected, even when attended by a medical professional. Cause With regard to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Childbirth
Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million births globally. In the developed countries, most deliveries occur in hospitals, while in the developing countries most are home births. The most common childbirth method worldwide is vaginal delivery. It involves four stages of labour: the shortening and opening of the cervix during the first stage, descent and birth of the baby during the second, the delivery of the placenta during the third, and the recovery of the mother and infant during the fourth stage, which is referred to as the postpartum. The first stage is characterized by abdominal cramping or back pain that typically lasts half a minute and occurs every 10 to 30 minutes. Contractions gradually becomes stronger and closer together. Since the pain of childbirth correlates with contractions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonsure
Tonsure () is the practice of cutting or shaving some or all of the hair on the scalp as a sign of religious devotion or humility. The term originates from the Latin word ' (meaning "clipping" or "shearing") and referred to a specific practice in medieval Roman Catholic Church, Catholicism, abandoned by papal order in 1972. Tonsure can also refer to the secular practice of shaving all or part of the scalp to show support or sympathy, or to designate mourning. Current usage more generally refers to cutting or shaving for monks, devotees, or mystics of any religion as a symbol of their renunciation of worldly fashion and esteem. Tonsure is still a traditional practice in Catholicism by specific religious orders (with papal permission). It is also commonly used in the Eastern Orthodox Church for newly baptised members and is frequently used for Buddhism, Buddhist novices, Bhikkhu, monks, and Bhikkhunī, nuns. The complete shaving of one's head bald, or just shortening the hair, exists ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambdoid Suture
The lambdoid suture (or lambdoidal suture) is a dense, fibrous connective tissue joint on the posterior aspect of the skull that connects the parietal bones with the occipital bone. It is continuous with the occipitomastoid suture. Structure The lambdoid suture is between the paired parietal bones and the occipital bone of the skull. It runs from the asterion on each side. Nerve supply The lambdoid suture may be supplied by a branch of the supraorbital nerve, a branch of the frontal branch of the trigeminal nerve. Clinical significance At birth, the bones of the skull do not meet. If certain bones of the skull grow too fast, then craniosynostosis (premature closure of the sutures) may occur. This can result in skull deformities. If the lambdoid suture closes too soon on one side, the skull will appear twisted and asymmetrical, a condition called "plagiocephaly". Plagiocephaly refers to the shape and not the condition. The condition is craniosynostosis. The lambdoid sut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described. Vertebrates comprise such groups as the following: * jawless fish, which include hagfish and lampreys * jawed vertebrates, which include: ** cartilaginous fish (sharks, rays, and ratfish) ** bony vertebrates, which include: *** ray-fins (the majority of living bony fish) *** lobe-fins, which include: **** coelacanths and lungfish **** tetrapods (limbed vertebrates) Extant vertebrates range in size from the frog species ''Paedophryne amauensis'', at as little as , to the blue whale, at up to . Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns. The vertebrates traditionally include the hagfish, which do no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sagittal Suture
The sagittal suture, also known as the interparietal suture and the ''sutura interparietalis'', is a dense, fibrous connective tissue joint between the two parietal bones of the skull. The term is derived from the Latin word ''sagitta'', meaning arrow. Structure The sagittal suture is formed from the fibrous connective tissue joint between the two parietal bones of the skull. It has a varied and irregular shape which arises during development. The pattern is different between the inside and the outside. Two anatomical landmarks are found on the sagittal suture: the bregma, and the vertex of the skull. The bregma is formed by the intersection of the sagittal and coronal sutures. The vertex is the highest point on the skull and is often near the midpoint of the sagittal suture. Development At birth, the bones of the skull do not meet. The gap that remains, which is approximately 5 mm wide, allows for the brain to continue to grow normally after birth. The inner parts of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coronal Suture
The coronal suture is a dense, fibrous connective tissue joint that separates the two parietal bones from the frontal bone of the skull. Structure The coronal suture lies between the paired parietal bones and the frontal bone of the skull. It runs from the pterion on each side. Nerve supply The coronal suture is likely supplied by a branch of the trigeminal nerve. Development The coronal suture is derived from the paraxial mesoderm. Clinical significance If certain bones of the skull grow too fast then premature fusion of the sutures may occur. This can result in skull deformities. There are two possible deformities that can be caused by the premature closure of the coronal suture: * a high, tower-like skull called "oxycephaly" or "turret skull". * a twisted and asymmetrical skull called "plagiocephaly". References * "Sagittal suture." ''Stedman's Medical Dictionary, 27th ed.'' (2000). * Moore, Keith L., and T.V.N. Persaud. ''The Developing Human: Clinically Orien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
