Digit (anatomy)

A digit is one of several most distal parts of a limb, such as fingers or toes, present in many vertebrates.

Names

Some languages have different names for hand and foot digits (English: respectively "finger" and "toe", French: "doigts" and "orteils").

In other languages, e.g. Russian, Polish, Spanish, Portuguese, Italian, Czech, Tagalog, Turkish, Bulgarian, and Persian, there are no specific one-word names for fingers and toes; these are called "digit of the hand" or "digit of the foot" instead.

Human digits

Humans normally have five digits on each extremity. Each digit is formed by several bones called phalanges, surrounded by soft tissue. Human fingers normally have a nail at the distal phalanx. The phenomenon of polydactyly occurs when extra digits are present; the utility of such a mutation is case-dependent.

Brain representation

Each finger has an orderly somatotopic representation on the cerebral cortex in the somatosensory cortex area 3b, part of area 1 and a distributed, overlapping representation in the supplementary motor area and primary motor area.

Anatomy

Anatomy is the branch of biology concerned with the study of the structure of organisms and their parts. In some of its facets, anatomy is related to embryology and comparative anatomy, which itself is closely related to evolutionary biology and phylogeny.Human anatomy is one of the basic essential sciences of medicine.

The discipline of anatomy is divided into macroscopic and microscopic anatomy. Macroscopic anatomy, or gross anatomy, is the examination of an animal's body parts using unaided eyesight. Gross anatomy also includes the branch of superficial anatomy. Microscopic anatomy involves the use of optical instruments in the study of the tissues of various structures, known as histology, and also in the study of cells.

The history of anatomy is characterized by a progressive understanding of the functions of the organs and structures of the human body. Methods have also improved dramatically, advancing from the examination of animals by dissection of carcasses and cadavers (corpses) to 20th century medical imaging techniques including X-ray, ultrasound, and magnetic resonance imaging.

World Memory Championships

The World Memory Championships is an organized competition of mental sports in which competitors memorize as much information as possible within a given period of time. The Championship has taken place annually since 1991 and has been staged by various organisations. The first winner was Dominic O'Brien.

Format

The World Championships consist of ten different disciplines, where the competitors have to memorize as much as they can in a period of time:

Dental anatomy

Dental anatomy is a field of anatomy dedicated to the study of human tooth structures. The development, appearance, and classification of teeth fall within its purview. (The function of teeth as they contact one another falls elsewhere, under dental occlusion.) Tooth formation begins before birth, and teeth's eventual morphology is dictated during this time. Dental anatomy is also a taxonomical science: it is concerned with the naming of teeth and the structures of which they are made, this information serving a practical purpose in dental treatment.

Usually, there are 20 primary ("baby") teeth and 28 to 32 permanent teeth, the last four being third molars or "wisdom teeth", each of which may or may not grow in. Among primary teeth, 10 usually are found in the maxilla (upper jaw) and the other 10 in the mandible (lower jaw). Among permanent teeth, 16 are found in the maxilla and the other 16 in the mandible. Most of the teeth have distinguishing features.

Growing of tooth

Tooth development is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth. Although many diverse species have teeth, non-human tooth development is largely the same as in humans. For human teeth to have a healthy oral environment, enamel, dentin, cementum, and the periodontium must all develop during appropriate stages of fetal development. Primary (baby) teeth start to form between the sixth and eighth weeks in utero, and permanent teeth begin to form in the twentieth week in utero. If teeth do not start to develop at or near these times, they will not develop at all.