The torso or trunk is an anatomical term for the central part or core of many animal bodies from which extend the neck and limbs. The torso includes: the thoracic segment of the trunk, the abdominal segment of the trunk, the perineum. Most critical organs are housed within the torso. In the upper chest, the heart and lungs are protected by the rib cage, the abdomen contains most of the organs responsible for digestion: the stomach, which breaks down digested food via gastric acid; the pelvic region houses both the male and female reproductive organs. The torso harbours many of the main groups of muscles in the body, including the: pectoral muscles abdominal muscles lateral muscle epaxial muscles The organs and other contents of the torso are supplied by nerves, which originate as nerve roots from the thoracic and lumbar parts of the spinal cord; some organs receive a nerve supply from the vagus nerve. The sensation to the skin is provided by: Lateral cutaneous branches of torso|Lateral cutaneous branches Dorsal cutaneous branches Belly cast Waist Belvedere Torso
In human anatomy, the head is at the top of the human body. It is maintained by the skull, which itself encloses the brain; the human head consists of a fleshy outer portion. The brain is enclosed within the skull; the head rests on the neck, the seven cervical vertebrae support it. The human head weighs between 5 and 11 pounds The face is the anterior part of the head, containing the eyes and mouth. On either side of the mouth, the cheeks provide a fleshy border to the oral cavity; the ears sit to either side of the head. The head receives blood supply through the external carotid arteries; these supply the area outside of the inside of the skull. The area inside the skull receives blood supply from the vertebral arteries, which travel up through the cervical vertebrae; the twelve pairs of cranial nerves provide the majority of nervous control to the head. The sensation to the face is provided by the branches of the trigeminal nerve, the fifth cranial nerve. Sensation to other portions of the head is provided by the cervical nerves.
Modern texts are in agreement about which areas of the skin are served by which nerves, but there are minor variations in some of the details. The borders designated by diagrams in the 1918 edition of Gray's Anatomy are similar but not identical to those accepted today; the cutaneous innervation of the head is as follows: Ophthalmic nerve Maxillary nerve Mandibular nerve Cervical plexus Dorsal rami of cervical nerves and others are in picture which show following in upper column The head contains sensory organs: two eyes, two ears, a nose and tongue inside of the mouth. It houses the brain. Together, these organs function as a processing center for the body by relaying sensory information to the brain. Humans can process information faster by having this central nerve cluster. For humans, the front of the head is the main distinguishing feature between different people due to its discernible features, such as eye and hair colors, shapes of the sensory organs, the wrinkles. Humans differentiate between faces because of the brain's predisposition toward facial recognition.
When observing a unfamiliar species, all faces seem nearly identical. Human infants are biologically programmed to recognize subtle differences in anthropomorphic facial features. People who have greater than average intelligence are sometimes depicted in cartoons as having bigger heads as a way of notionally indicating that they have a "larger brain". Additionally, in science fiction, an extraterrestrial having a big head is symbolic of high intelligence. Despite this depiction, advances in neurobiology have shown that the functional diversity of the brain means that a difference in overall brain size is only to moderately correlated to differences in overall intelligence between two humans; the head is a source for many metaphors and metonymies in human language, including referring to things near the human head, things physically similar to the way a head is arranged spatially to a body and things that represent some characteristics associated with the head, such as intelligence. Ancient Greeks had a method for evaluating sexual attractiveness based on the Golden ratio, part of which included measurements of the head.
Headpieces can signify status, religious/spiritual beliefs, social grouping, team affiliation, occupation, or fashion choices. In many cultures, covering the head is seen as a sign of respect; some or all of the head must be covered and veiled when entering holy places or places of prayer. For many centuries, women in Europe, the Middle East, South Asia have covered their hair as a sign of modesty; this trend has changed drastically in Europe in the 20th century, although is still observed in other parts of the world. In addition, a number of religions require men to wear specific head clothing—such as the Islamic Taqiyah, Jewish yarmulke, or the Sikh turban; the same goes for Christian nun's habit. A hat is a head covering. Hats may be worn as part of a uniform or used as a protective device, such as a hard hat, a covering for warmth, or a fashion accessory. Hats can be indicative of social status in some areas of the world. While numerous charts detailing head sizes in infants and children exist, most do not measure average head circumference past the age of 21.
Reference charts for adult head circumference generally feature homogeneous samples and fail to take height and weight into account. One study in the United States estimated the average human head circumference to be 55 centimetres in females and 57 centimetres in males. A British study by Newcastle University showed an average size of 55.2 cm for females and 57.2 cm for males with average size varying proportionally with height Macrocephaly can be an indicator of increased risk for some types of cancer in individuals who carry the genetic mutation that causes Cowden syndrome. For adults, this refers to head sizes greater than 58 centimeters in men or greater than 57 centimeters in women. Human body Head and neck anatomy 8. Human head Campbell, Bernard Grant. Human Evolution: An Introduction to Man's Adaptations, 4th edition
Anatomical terminology is a form of scientific terminology used by anatomists and health professionals such as doctors. Anatomical terminology uses many unique terms and prefixes deriving from Ancient Greek and Latin; these terms can be confusing to those unfamiliar with them, but can be more precise, reducing ambiguity and errors. Since these anatomical terms are not used in everyday conversation, their meanings are less to change, less to be misinterpreted. To illustrate how inexact day-to-day language can be: a scar "above the wrist" could be located on the forearm two or three inches away from the hand or at the base of the hand. By using precise anatomical terminology such ambiguity is eliminated. An international standard for anatomical terminology, Terminologia Anatomica has been created. Anatomical terminology has quite regular morphology, the same prefixes and suffixes are used to add meanings to different roots; the root of a term refers to an organ or tissue. For example, the Latin names of structures such as musculus biceps brachii can be split up and refer to, musculus for muscle, biceps for "two-headed", brachii as in the brachial region of the arm.
The first word describes what is being spoken about, the second describes it, the third points to location. When describing the position of anatomical structures, structures may be described according to the anatomical landmark they are near; these landmarks may include structures, such as the umbilicus or sternum, or anatomical lines, such as the midclavicular line from the centre of the clavicle. The cephalon or cephalic region refers to the head; this area is further differentiated into the cranium, frons, auris, nasus and mentum. The neck area is called cervical region. Examples of structures named according to this include the frontalis muscle, submental lymph nodes, buccal membrane and orbicularis oculi muscle. Sometimes, unique terminology is used to reduce confusion in different parts of the body. For example, different terms are used when it comes to the skull in compliance with its embryonic origin and its tilted position compared to in other animals. Here, Rostral refers to proximity to the front of the nose, is used when describing the skull.
Different terminology is used in the arms, in part to reduce ambiguity as to what the "front", "back", "inner" and "outer" surfaces are. For this reason, the terms below are used: Radial referring to the radius bone, seen laterally in the standard anatomical position. Ulnar referring to the ulna bone, medially positioned when in the standard anatomical position. Other terms are used to describe the movement and actions of the hands and feet, other structures such as the eye. International morphological terminology is used by the colleges of medicine and dentistry and other areas of the health sciences, it facilitates communication and exchanges between scientists from different countries of the world and it is used daily in the fields of research and medical care. The international morphological terminology refers to morphological sciences as a biological sciences' branch. In this field, the form and structure are examined as well as the changes or developments in the organism, it is functional.
It covers the gross anatomy and the microscopic of living beings. It involves the anatomy of the adult, it includes comparative anatomy between different species. The vocabulary is extensive and complex, requires a systematic presentation. Within the international field, a group of experts reviews and discusses the morphological terms of the structures of the human body, forming today's Terminology Committee from the International Federation of Associations of Anatomists, it deals with the anatomical and embryologic terminology. In the Latin American field, there are meetings called Iberian Latin American Symposium Terminology, where a group of experts of the Pan American Association of Anatomy that speak Spanish and Portuguese and studies the international morphological terminology; the current international standard for human anatomical terminology is based on the Terminologia Anatomica. It was developed by the Federative Committee on Anatomical Terminology and the International Federation of Associations of Anatomists and was released in 1998.
It supersedes Nomina Anatomica. Terminologia Anatomica contains terminology for about 7500 human gross anatomical structures. For microanatomy, known as histology, a similar standard exists in Terminologia Histologica, for embryology, the study of development, a standard exists in Terminologia Embryologica; these standards specify accepted names that can be used to refer to histological and embryological structures in journal articles and other areas. As of September 2016, two sections of the Terminologia Anatomica, including central nervous system and peripheral nervous system, were merged to form the Terminologia Neuroanatomica; the Terminologia Anatomica has been perceived with a considerable criticism regarding its content including coverage and spelling mistakes and errors. Anatomical terminology is chosen to highlight the relative location of body structures. For instance, an anatomist might describe one band of tissue as "inferior to" another or a physician might describe a tumor as "superficial to" a deeper body structure.
Anatomical terms used to describe location
Time is the indefinite continued progress of existence and events that occur in irreversible succession through the past, in the present, the future. Time is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, to quantify rates of change of quantities in material reality or in the conscious experience. Time is referred to as a fourth dimension, along with three spatial dimensions. Time has long been an important subject of study in religion and science, but defining it in a manner applicable to all fields without circularity has eluded scholars. Diverse fields such as business, sports, the sciences, the performing arts all incorporate some notion of time into their respective measuring systems. Time in physics is unambiguously operationally defined as "what a clock reads". See Units of Time. Time is one of the seven fundamental physical quantities in both the International System of Units and International System of Quantities.
Time is used to define other quantities – such as velocity – so defining time in terms of such quantities would result in circularity of definition. An operational definition of time, wherein one says that observing a certain number of repetitions of one or another standard cyclical event constitutes one standard unit such as the second, is useful in the conduct of both advanced experiments and everyday affairs of life; the operational definition leaves aside the question whether there is something called time, apart from the counting activity just mentioned, that flows and that can be measured. Investigations of a single continuum called spacetime bring questions about space into questions about time, questions that have their roots in the works of early students of natural philosophy. Temporal measurement has occupied scientists and technologists, was a prime motivation in navigation and astronomy. Periodic events and periodic motion have long served as standards for units of time. Examples include the apparent motion of the sun across the sky, the phases of the moon, the swing of a pendulum, the beat of a heart.
The international unit of time, the second, is defined by measuring the electronic transition frequency of caesium atoms. Time is of significant social importance, having economic value as well as personal value, due to an awareness of the limited time in each day and in human life spans. Speaking, methods of temporal measurement, or chronometry, take two distinct forms: the calendar, a mathematical tool for organising intervals of time, the clock, a physical mechanism that counts the passage of time. In day-to-day life, the clock is consulted for periods less than a day whereas the calendar is consulted for periods longer than a day. Personal electronic devices display both calendars and clocks simultaneously; the number that marks the occurrence of a specified event as to hour or date is obtained by counting from a fiducial epoch – a central reference point. Artifacts from the Paleolithic suggest that the moon was used to reckon time as early as 6,000 years ago. Lunar calendars were among the first to appear, with years of either 13 lunar months.
Without intercalation to add days or months to some years, seasons drift in a calendar based on twelve lunar months. Lunisolar calendars have a thirteenth month added to some years to make up for the difference between a full year and a year of just twelve lunar months; the numbers twelve and thirteen came to feature prominently in many cultures, at least due to this relationship of months to years. Other early forms of calendars originated in Mesoamerica in ancient Mayan civilization; these calendars were religiously and astronomically based, with 18 months in a year and 20 days in a month, plus five epagomenal days at the end of the year. The reforms of Julius Caesar in 45 BC put the Roman world on a solar calendar; this Julian calendar was faulty in that its intercalation still allowed the astronomical solstices and equinoxes to advance against it by about 11 minutes per year. Pope Gregory XIII introduced a correction in 1582. During the French Revolution, a new clock and calendar were invented in attempt to de-Christianize time and create a more rational system in order to replace the Gregorian calendar.
The French Republican Calendar's days consisted of ten hours of a hundred minutes of a hundred seconds, which marked a deviation from the 12-based duodecimal system used in many other devices by many cultures. The system was abolished in 1806. A large variety of devices have been invented to measure time; the study of these devices is called horology. An Egyptian device that dates to c. 1500 BC, similar in shape to a bent T-square, measured the passage of time from the shadow cast by its crossbar on a nonlinear rule. The T was oriented eastward in the mornings. At noon, the device was turned around so. A sundial uses a gnomon to cast a shadow on a set of markings calibrated to the hour; the position of the shadow marks the hour in local time. The idea to separate the day into smaller parts is credited to Egyptians because of their sundials, which operated on a duodecimal system; the importance of the number 12 is due to the number of lunar cycles in a year and the number of stars used to count the passage of night.
The most precise timekeeping device of the ancient
A head is the part of an organism which includes the ears, forehead, chin, eyes and mouth, each of which aid in various sensory functions such as sight, hearing and taste, respectively. Some simple animals may not have a head, but many bilaterally symmetric forms do, regardless of size. Heads develop in animals by an evolutionary trend known as cephalization. In bilaterally symmetrical animals, nervous tissues concentrate at the anterior region, forming structures responsible for information processing. Through biological evolution, sense organs and feeding structures concentrate into the anterior region; the human head is an anatomical unit that consists of hyoid bone and cervical vertebrae. The term "skull" collectively denotes the cranium; the skull can be described as being composed of the cranium, which encloses the cranial cavity, the facial skeleton. There are fourteen in the facial skeleton. Sculptures of human heads are based on a skeletal structure that consists of a cranium and cheekbone.
Though the number of muscles making up the face is consistent between sculptures, the shape of the muscles varies based on the function and expressions reflected on the faces of the subjects. Proponents of identism believe. Philosopher John Searle asserts his identist beliefs, stating "the brain is the only thing in the human head". Dr. Henry Bennet-Clark has stated that the head encloses billions of "miniagents and microagents"; the evolution of a head is associated with the cephalization that occurred in Bilateria some 555 million years ago. In some arthropods trilobites, the cephalon, or cephalic region, is the region of the head, a collective of "fused segments". A typical insect head is composed of eyes and components of mouth; as these components differ from insect to insect, they form important identification links. Eyes in the head found, in several types of insects, are in the form of a pair of compound eyes with multiple faces. In many other types of insects the compound eyes are seen in a "single facet or group of single facets".
In some case, the eyes may be seen as marks on the dorsal or located near or toward the head, two or three ocelli. Antennae on the insect's head is found in the form of segmented attachments, in pairs, that are located between the eyes; these are in varying shapes and sizes, in the form of filaments or in different enlarged or clubbed form. Insects have mouth parts in various shapes depending on their feeding habits. Labrum is the "upper lip", in the front area of the head and is the most exterior part. A pair of mandible is found on backside of the labrum flanking the side of the mouth, succeeded by a pair of maxillae each of, known as maxilliary palp. At the back side of the mouth is lower lip. There is an extra mouth part in some insects, termed as hypopharynx, located between the maxillac. Though invertebrate chordates – such as the tunicate larvae or the lancelets – have heads, there has been a question of how the vertebrate head, characterized by a bony skull separated from the main body, might have evolved from the head structures of these animals.
According to Hyman, the evolution of the head in the vertebrates has occurred by the fusion of a fixed number of anterior segments, in the same manner as in other "heteronomously segmented animals". In some cases, segments or a portion of the segments disappear; the head segments lose most of its systems except for the nervous system. With the progressive development of cephalization, "the head incorporates more and more of the adjacent segments into its structure, so that in general it may be said that the higher the degree of cephalization the greater is the number of segments composing the head". In the 1980s, the "new head hypothesis" was proposed, suggesting that the vertebrate head is an evolutionary novelty resulting from the emergence of neural crest and cranial placodes. In 2014, a transient larva tissue of the lancelet was found to be indistinguishable from the neural crest-derived cartilage which forms the vertebrate skull, suggesting that persistence of this tissue and expansion into the entire headspace could be a viable evolutionary route to formation of the vertebrate head.
The heads of humans and other animals are recurring charges in heraldry. Heads of humans are sometimes blazoned as a "man's head", but are far more described in greater detail, either characteristic of a particular race or nationality, or identified. Several varieties of women's heads occur, including maidens' heads, ladies' heads, nuns' heads, queens' heads; the arms of Devaney of Norfolk include "three nun's heads veiled couped at the shoulders proper," and the bust of a queen occurs in the arms of Queenborough, Kent. Infants' or children's heads are couped at the shoulders with a snake wrapped around the neck. One of the ways of drawing sketches of heads—as Jack Hamm advises—is to develop it in six well-defined
Vertebrates comprise all species of animals within the subphylum Vertebrata. Vertebrates represent the overwhelming majority of the phylum Chordata, with about 69,276 species described. Vertebrates include the jawless fishes and jawed vertebrates, which include the cartilaginous fishes and the bony fishes; the bony fishes in turn, cladistically speaking include the tetrapods, which include amphibians, reptiles and mammals. Extant vertebrates range in size from the frog species Paedophryne amauensis, at as little as 7.7 mm, to the blue whale, at up to 33 m. Vertebrates make up less than five percent of all described animal species; the vertebrates traditionally include the hagfish, which do not have proper vertebrae due to their loss in evolution, though their closest living relatives, the lampreys, do. Hagfish do, possess a cranium. For this reason, the vertebrate subphylum is sometimes referred to as "Craniata" when discussing morphology. Molecular analysis since 1992 has suggested that hagfish are most related to lampreys, so are vertebrates in a monophyletic sense.
Others consider them a sister group of vertebrates in the common taxon of craniata. The word vertebrate derives from the Latin word vertebratus. Vertebrate is derived from the word vertebra, which refers to any of the bones or segments of the spinal column. All vertebrates are built along the basic chordate body plan: a stiff rod running through the length of the animal, with a hollow tube of nervous tissue above it and the gastrointestinal tract below. In all vertebrates, the mouth is found at, or right below, the anterior end of the animal, while the anus opens to the exterior before the end of the body; the remaining part of the body continuing after the anus forms a tail with vertebrae and spinal cord, but no gut. The defining characteristic of a vertebrate is the vertebral column, in which the notochord found in all chordates has been replaced by a segmented series of stiffer elements separated by mobile joints. However, a few vertebrates have secondarily lost this anatomy, retaining the notochord into adulthood, such as the sturgeon and coelacanth.
Jawed vertebrates are typified by paired appendages, but this trait is not required in order for an animal to be a vertebrate. All basal vertebrates breathe with gills; the gills are carried right behind the head, bordering the posterior margins of a series of openings from the pharynx to the exterior. Each gill is supported by a cartilagenous or bony gill arch; the bony fish have three pairs of arches, cartilaginous fish have five to seven pairs, while the primitive jawless fish have seven. The vertebrate ancestor no doubt had more arches than this, as some of their chordate relatives have more than 50 pairs of gills. In amphibians and some primitive bony fishes, the larvae bear external gills, branching off from the gill arches; these are reduced in adulthood, their function taken over by the gills proper in fishes and by lungs in most amphibians. Some amphibians retain the external larval gills in adulthood, the complex internal gill system as seen in fish being irrevocably lost early in the evolution of tetrapods.
While the more derived vertebrates lack gills, the gill arches form during fetal development, form the basis of essential structures such as jaws, the thyroid gland, the larynx, the columella and, in mammals, the malleus and incus. The central nervous system of vertebrates is based on a hollow nerve cord running along the length of the animal. Of particular importance and unique to vertebrates is the presence of neural crest cells; these are progenitors of stem cells, critical to coordinating the functions of cellular components. Neural crest cells migrate through the body from the nerve cord during development, initiate the formation of neural ganglia and structures such as the jaws and skull; the vertebrates are the only chordate group to exhibit cephalisation, the concentration of brain functions in the head. A slight swelling of the anterior end of the nerve cord is found in the lancelet, a chordate, though it lacks the eyes and other complex sense organs comparable to those of vertebrates.
Other chordates do not show any trends towards cephalisation. A peripheral nervous system branches out from the nerve cord to innervate the various systems; the front end of the nerve tube is expanded by a thickening of the walls and expansion of the central canal of spinal cord into three primary brain vesicles: The prosencephalon and rhombencephalon, further differentiated in the various vertebrate groups. Two laterally placed eyes form around outgrowths from the midbrain, except in hagfish, though this may be a secondary loss; the forebrain is well developed and subdivided in most tetrapods, while the midbrain dominates in many fish and some salamanders. Vesicles of the forebrain are paired, giving rise to hemispheres like the cerebral hemispheres in mammals; the resulting anatomy of the central nervous system, with a single hollow nerve cord topped by a series of vesicles, is unique to vertebrates. All invertebrates with well-developed brains, such as insects and squids, have a ventral rather than dorsal system of ganglions, with a split brain stem running on each side of the mouth or gut.
Vertebrates originated about 525 million years ago during the Cambrian explosion, which saw
The pterion is the region where the frontal, parietal and sphenoid bones join together. It is located on the side of the skull, just behind the temple; the pterion is located in the temporal fossa 2.6 cm behind and 1.3 cm above the posterolateral margin of the frontozygomatic suture. It is the junction between four bones: the parietal bone the squamous part of temporal bone the greater wing of sphenoid bone the frontal boneThese bones are joined by five cranial sutures: the sphenoparietal suture joins the sphenoid and parietal bones the coronal suture joins the frontal bone to the sphenoid and parietal bones the squamous suture joins the temporal bone to the sphenoid and parietal bones the sphenofrontal suture joins the sphenoid and frontal bones the sphenosquamosal suture joins the sphenoid and temporal bones The pterion is known as the weakest part of the skull; the anterior division of the middle meningeal artery runs underneath the pterion. A traumatic blow to the pterion may rupture the middle meningeal artery causing an epidural haematoma.
The pterion may be fractured indirectly by blows to the top or back of the head that place sufficient force on the skull to fracture the pterion. The pterion receives its name from the Greek root pteron. In Greek mythology, messenger of the gods, was enabled to fly by winged sandals, wings on his head, which were attached at the pterion; this article incorporates text in the public domain from page 182 of the 20th edition of Gray's Anatomy Anatomy figure: 22:01-04 at Human Anatomy Online, SUNY Downstate Medical Center Diagram - look for #24