|
Fontanelle
A fontanelle (or fontanel) (colloquially, soft spot) is an anatomical feature of the infant human skull comprising soft membranous gaps ( sutures) between the cranial bones that make up the calvaria of a fetus or an infant. Fontanelles allow for stretching and deformation of the neurocranium both during birth and later as the brain expands faster than the surrounding bone can grow. Premature complete ossification of the sutures is called craniosynostosis. After infancy, the anterior fontanelle is known as the bregma. Structure An infant's skull consists of five main bones: two frontal bones, two parietal bones, and one occipital bone. These are joined by fibrous sutures, which allow movement that facilitates childbirth and brain growth. * Posterior fontanelle is triangle-shaped. It lies at the junction between the sagittal suture and lambdoid suture. At birth, the skull features a small posterior fontanelle with an open area covered by a tough membrane, where the two pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anterior Fontanelle
The anterior fontanelle (bregmatic fontanelle, frontal fontanelle) is the largest fontanelle, and is placed at the junction of the sagittal suture, coronal suture, and frontal suture; it is lozenge-shaped, and measures about 4 cm in its antero-posterior and 2.5 cm in its transverse diameter. The fontanelle allows the skull to deform during birth to ease its passage through the birth canal and for expansion of the brain after birth. The anterior fontanelle typically closes between the ages of 12 and 18 months. Clinical significance The anterior fontanelle is useful clinically. Examination of an infant includes palpating the anterior fontanelle. A sunken fontanelle indicates dehydration whereas a very tense or bulging anterior fontanelle indicates raised intracranial pressure Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury ( mmHg) and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Skull
The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent parts: the neurocranium and the facial skeleton, which evolved from the first pharyngeal arch. The skull forms the frontmost portion of the axial skeleton and is a product of cephalization and vesicular enlargement of the brain, with several special senses structures such as the eyes, ears, nose, tongue and, in fish, specialized tactile organs such as barbels near the mouth. The skull is composed of three types of bone: cranial bones, facial bones and ossicles, which is made up of a number of fused flat and irregular bones. The cranial bones are joined at firm fibrous junctions called sutures and contains many foramina, fossae, processes, and sinuses. In zoology, the openings in the skull are called fenestrae, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bregma
The bregma is the anatomical point on the skull at which the coronal suture is intersected perpendicularly by the sagittal suture. Structure The bregma is located at the intersection of the coronal suture and the sagittal suture on the superior middle portion of the calvaria. It is the point where the frontal bone and the two parietal bones meet. Development The bregma is known as the anterior fontanelle during infancy. The anterior fontanelle is membranous and closes in the first 18-36 months of life. Clinical significance Cleidocranial dysostosis In the birth defect cleidocranial dysostosis, the anterior fontanelle never closes to form the bregma. Surgical landmark The bregma is often used as a reference point for stereotactic surgery of the brain. It may be identified by blunt scraping of the surface of the skull and washing to make the meeting point of the sutures clearer. Neonatal examination Examination of an infant includes palpating the anterior fontanelle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior Fontanelle
The posterior fontanelle (lambdoid fontanelle, occipital fontanelle) is a gap between bones in the human skull (known as fontanelle), triangular in form and situated at the junction of the sagittal suture and lambdoidal suture. It generally closes in 6–8 weeks from birth. The cranial point in adults corresponding the fontanelle is called ''lambda''. A delay in closure is associated with congenital hypothyroidism Hypothyroidism is an endocrine disease in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as cold intolerance, poor ability to tolerate cold, fatigue, extreme fatigue, muscle aches, co .... References Skull {{musculoskeletal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cleidocranial Dysostosis
Cleidocranial dysostosis (CCD), also called cleidocranial dysplasia, is a congenital disorder, birth defect that mostly affects the bones and teeth. The collarbones are typically either poorly developed or absent, which allows the shoulders to be brought close together. The front of the skull often does not close until later, and those affected are often shorter than average. Other symptoms may include a prominent forehead, wide set eyes, abnormal teeth, and a flat nose. Symptoms vary among people; however, cognitive function is typically unaffected. The condition is either heredity, inherited or occurs as a new mutation. It is inherited in an autosomal dominant manner. It is due to a defect in the RUNX2 gene which is involved in bone formation. Diagnosis is suspected based on symptoms and X-rays with confirmation by genetic testing. Other conditions that can produce similar symptoms include mandibuloacral dysplasia, pyknodysostosis, osteogenesis imperfecta, and Hajdu-Cheney synd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parietal Bone
The parietal bones ( ) are two bones in the skull which, when joined at a fibrous joint known as a cranial suture, form the sides and roof of the neurocranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin ''paries'' (''-ietis''), wall. Surfaces External The external surface [Fig. 1] is convex, smooth, and marked near the center by an eminence, the parietal eminence (''tuber parietale''), which indicates the point where ossification commenced. Crossing the middle of the bone in an arched direction are two curved lines, the superior and inferior temporal lines; the former gives attachment to the temporal fascia, and the latter indicates the upper limit of the muscular origin of the temporal muscle. Above these lines the bone is covered by a tough layer of fibrous tissue – the epicranial aponeurosis; below them it forms part of the temporal fossa, and affords attachment to the temporal mu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lambda (anatomy)
The lambda is the meeting point of the sagittal suture and the lambdoid suture. This is also the point of the occipital angle. It is named after the Greek letter lambda. Structure The lambda is the meeting point of the sagittal suture and the lambdoid suture. It may be the exact midpoint of the lambdoid suture, but often deviates slightly from the midline. This is also the point of the occipital angle. Development In the foetus, the lambda is membranous, and is called the posterior fontanelle. Etymology The lambda is named after the Greek letter lambda Lambda (; uppercase , lowercase ; , ''lám(b)da'') is the eleventh letter of the Greek alphabet, representing the voiced alveolar lateral approximant . In the system of Greek numerals, lambda has a value of 30. Lambda is derived from the Phoen ..., whose lowercase form (λ) resembles the junction formed by the sutures. References External links * Skull {{musculoskeletal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calvaria (skull)
The calvaria is the top part of the skull. It is the superior 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 suture (joint), 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 incorrectly 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 the bregma. The point at which the two parietal bones and the occipital bone meet is kn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Occipital Bone
The occipital bone () is a neurocranium, cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone lies over the occipital lobes of the cerebrum. At the base of the skull in the occipital bone, there is a large oval opening called the foramen magnum, which allows the passage of the spinal cord. Like the other cranial bones, it is classed as a flat bone. Due to its many attachments and features, the occipital bone is described in terms of separate parts. From its front to the back is the basilar part of occipital bone, basilar part, also called the basioccipital, at the sides of the foramen magnum are the lateral parts of occipital bone, lateral parts, also called the exoccipitals, and the back is named as the squamous part of occipital bone, squamous part. The basilar part is a thick, somewhat quadrilateral piece in front of the foramen magnum and directed toward ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sutures Of Skull
In anatomy, fibrous joints are joints connected by fibrous tissue, consisting mainly of collagen. These are fixed joints where bones are united by a layer of white fibrous tissue of varying thickness. In the skull, the joints between the bones are called sutures. Such immovable joints are also referred to as synarthroses. Types Most fibrous joints are also called "fixed" or "immovable". These joints have no joint cavity and are connected via fibrous connective tissue. * Sutures: The skull bones are connected by fibrous joints called '' sutures''. In fetal skulls, the sutures are wide to allow slight movement during birth. They later become rigid ( synarthrodial). * Syndesmosis: Some of the long bones in the body such as the radius and ulna in the forearm are joined by a ''syndesmosis'' (along the interosseous membrane). Syndemoses are slightly moveable ( amphiarthrodial). The distal tibiofibular joint is another example. * A ''gomphosis'' is a joint between the root of a ... [...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, craniosynostosis, may occur. This can result in skull deformities. These deformities include: * Brachycephaly (both sides) * Plagiocephaly (one side only) * Oxycephaly (both sides) References * "Sagittal suture." ''Stedman's Medical Dictionary, 27th ed.'' (2000). * Moore, Keith L., and T.V.N. Persaud. ''The Developing Human: Clinically Oriented Embryology, 7th ed.'' (2003). Additional images File:Coronal suture - ani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
