Tooth
A tooth is a hard, calcified structure found in the jaws of many vertebrates and used to break down food. Some animals carnivores use teeth for hunting or for defensive purposes; the roots of teeth are covered by gums. Teeth hardness; the cellular tissues that become teeth originate from the embryonic germ layer, the ectoderm. The general structure of teeth is similar across the vertebrates, although there is considerable variation in their form and position; the teeth of mammals have deep roots, this pattern is found in some fish, in crocodilians. In most teleost fish, the teeth are attached to the outer surface of the bone, while in lizards they are attached to the inner surface of the jaw by one side. In cartilaginous fish, such as sharks, the teeth are attached by tough ligaments to the hoops of cartilage that form the jaw; some animals develop only one set of teeth. Sharks, for example, grow a new set of teeth. Rodent incisors grow and wear away continually through gnawing, which helps maintain constant length.
The industry of the beaver is due in part to this qualification. Many rodents such as voles and guinea pigs, but not mice, as well as leporidae like rabbits, have continuously growing molars in addition to incisors. Teeth are not always attached to the jaw. In many reptiles and fish, teeth are attached to the palate or to the floor of the mouth, forming additional rows inside those on the jaws proper; some teleosts have teeth in the pharynx. While not true teeth in the usual sense, the dermal denticles of sharks are identical in structure and are to have the same evolutionary origin. Indeed, teeth appear to have first evolved in sharks, are not found in the more primitive jawless fish – while lampreys do have tooth-like structures on the tongue, these are in fact, composed of keratin, not of dentine or enamel, bear no relationship to true teeth. Though "modern" teeth-like structures with dentine and enamel have been found in late conodonts, they are now supposed to have evolved independently of vertebrates' teeth.
Living amphibians have small teeth, or none at all, since they feed only on soft foods. In reptiles, teeth are simple and conical in shape, although there is some variation between species, most notably the venom-injecting fangs of snakes; the pattern of incisors, canines and molars is found only in mammals, to varying extents, in their evolutionary ancestors. The numbers of these types of teeth vary between species; the genes governing tooth development in mammals are homologous to those involved in the development of fish scales. Study of a tooth plate of a fossil of the extinct fish Romundina stellina showed that the teeth and scales were made of the same tissues found in mammal teeth, lending support to the theory that teeth evolved as a modification of scales. Teeth are among the most distinctive features of mammal species. Paleontologists use teeth to determine their relationships; the shape of the animal's teeth are related to its diet. For example, plant matter is hard to digest, so herbivores have many molars for chewing and grinding.
Carnivores, on the other hand, have canine teeth to tear meat. Mammals, in general, are diphyodont. In humans, the first set starts to appear at about six months of age, although some babies are born with one or more visible teeth, known as neonatal teeth. Normal tooth eruption at about six months can be painful. Kangaroos and manatees are unusual among mammals because they are polyphyodonts. In Aardvarks, teeth lack enamel and have many pulp tubules, hence the name of the order Tubulidentata. In dogs, the teeth are less than humans to form dental cavities because of the high pH of dog saliva, which prevents enamel from demineralizing. Sometimes called cuspids, these teeth are shaped like points and are used for tearing and grasping food Like human teeth, whale teeth have polyp-like protrusions located on the root surface of the tooth; these polyps are made of cementum in both species, but in human teeth, the protrusions are located on the outside of the root, while in whales the nodule is located on the inside of the pulp chamber.
While the roots of human teeth are made of cementum on the outer surface, whales have cementum on the entire surface of the tooth with a small layer of enamel at the tip. This small enamel layer is only seen in older whales where the cementum has been worn away to show the underlying enamel; the toothed whale is a suborder of the cetaceans characterized by having teeth. The teeth differ among the species, they may be numerous, with some dolphins bearing over 100 teeth in their jaws. On the other hand, the narwhals have a giant unicorn-like tusk, a tooth containing millions of sensory pathways and used for sensing during feeding and mating, it is the most neurologically complex tooth known. Beaked whales are toothless, with only bizarre teeth found in males; these teeth may be used for feeding but for demonstrating aggression and showmanship. In humans there are 20 primary teeth, 28 to 32 of what's known as permanent teeth, in addition to other four being third molars or wisdom teeth, each of which may or may not g
Joint capsule
In anatomy, a joint capsule or articular capsule is an envelope surrounding a synovial joint. Each joint capsule has two parts: an outer fibrous layer or membrane, an inner synovial layer or membrane; each capsule consists of two layers or membranes: an outer composed of avascular white fibrous tissue an inner, a secreting layerOn the inside of the capsule, articular cartilage covers the end surfaces of the bones that articulate within that joint. The outer layer is innervated by the same nerves which perforate through the adjacent muscles associated with the joint; the fibrous membrane of the joint capsule is attached to the whole circumference of the articular end of each bone entering into the joint, thus surrounds the articulation. It is made up of dense irregular connective tissue. It's a long spongy tissue. Frozen shoulder is a disorder. Plica syndrome is a disorder in which the synovial plica becomes inflamed and causes abnormal biomechanics in the knee. Articular capsule of the humerus Articular capsule of the knee joint Atlanto-axial joint Capsule of atlantooccipital articulation Capsule of hip joint Capsule of temporomandibular joint This article incorporates text in the public domain from page 282 of the 20th edition of Gray's Anatomy Cross section image: pelvis/pelvis-e12-15—Plastination Laboratory at the Medical University of Vienna
Sacrotuberous ligament
The sacrotuberous ligament is situated at the lower and back part of the pelvis. It is flat, triangular in form, it runs from the sacrum to the tuberosity of the ischium. It is a remnant of part of Biceps femoris muscle; the sacrotuberous ligament is attached by its broad base to the posterior superior iliac spine, the posterior sacroiliac ligaments, to the lower transverse sacral tubercles and the lateral margins of the lower sacrum and upper coccyx. Its oblique fibres descend laterally, converging to form a thick, narrow band that widens again below and is attached to the medial margin of the ischial tuberosity, it spreads along the ischial ramus as the falciform process, whose concave edge blends with the fascial sheath of the internal pudendal vessels and pudendal nerve. The lowest fibres of gluteus maximus are attached to the posterior surface of the ligament; the ligament is pierced by the coccygeal branches of the inferior gluteal artery, the perforating cutaneous nerve and filaments of the coccygeal plexus.
The membranous falciform process of the sacrotuberous ligament was found to be absent in 13% of cadavers. When present it extends towards the ischioanal fossa travelling along the ischial ramus and fusing with the obturator fascia; the lower border of the ligament was found to be directly continuous with the tendon of origin of the long head of the Biceps femoris in 50% of subjects. Biceps femoris could therefore act to stabilise the sacroiliac joint via the sacrotuberous ligament; the sacrotuberous ligament contains the coccygeal branch of the inferior gluteal artery. If the pudendal nerve becomes entrapped between this ligament and the sacrospinous ligament causing perineal pain, the sacrotuberous ligament is surgically severed to relieve the pain; this article incorporates text in the public domain from page 309 of the 20th edition of Gray's Anatomy Anatomy figure: 13:03-04 at Human Anatomy Online, SUNY Downstate Medical Center – "Deep muscles of the gluteal region with gluteus medius and maximus muscles removed."
Anatomy figure: 17:02-05 at Human Anatomy Online, SUNY Downstate Medical Center – "Posterior view of the bones and ligaments of the hip joint." Anatomy photo:41:os-0114 at the SUNY Downstate Medical Center – "The Female Perineum" Anatomy photo:42:12-0102 at the SUNY Downstate Medical Center – "The Male Perineum and the Penis: Boundaries of the Ischioanal fossa" Anatomy image:9075 at the SUNY Downstate Medical Center hip/hip%20ligaments/ligaments7 at the Dartmouth Medical School's Department of Anatomy
Palmar radiocarpal ligament
The palmar radiocarpal ligament is a broad membranous band, attached above to the distal end of the radius, to the scaphoid and the triquetrum of the carpal bones in the wrist. Some being continued to the capitate. In addition to this broad membrane, there is a rounded fasciculus, superficial to the rest, which reaches from the base of the styloid process of the ulna to the lunate and triangular bones; the ligament is perforated by apertures for the passage of vessels, It is in relation, in front, with the tendons of the flexor digitorum profundus and flexor pollicis longus. Behind, it is adherent to the anterior border of the articular disk of the distal radioulnar articulation; some sources break down the components of the ligament as follows: radiolunate, radiocapitate and radioscaphoid. Other sources combine the radioscaphoid and radiocapitate into a "radioscaphocapitate"; this article incorporates text in the public domain from page 327 of the 20th edition of Gray's Anatomy Anatomy photo:10:st-1504 at the SUNY Downstate Medical Center
Anterior sacroiliac ligament
The anterior sacroiliac ligament consists of numerous thin bands, which connect the anterior surface of the lateral part of the sacrum to the margin of the auricular surface of the ilium and to the preauricular sulcus. Posterior sacroiliac ligament This article incorporates text in the public domain from page 307 of the 20th edition of Gray's Anatomy pelvis at The Anatomy Lesson by Wesley Norman
Quadrupedalism
Quadrupedalism or pronograde posture is a form of terrestrial locomotion in animals using four limbs or legs. An animal or machine that moves in a quadrupedal manner is known as a quadruped, meaning "four feet"; the majority of quadrupeds are vertebrate animals, including mammals such as cattle and cats, reptiles such as lizards. Few other animals are quadrupedal, though a few birds like the shoebill sometimes use their wings to right themselves after lunging at prey. Although the words quadruped and tetrapod are both derived from terms meaning "four-footed", they have distinct meanings. A tetrapod is any member of the taxonomic unit Tetrapoda whereas a quadruped uses four limbs for locomotion. Not all tetrapods are quadrupeds and not all quadrupeds are tetrapods; the distinction between quadrupeds and tetrapods is important in evolutionary biology in the context of tetrapods whose limbs have adapted to other roles. All of these animals are tetrapods. Snakes, whose limbs have become vestigial or lost are tetrapods.
Most quadrupedal animals are tetrapods but there are a few exceptions. For instance, among the insects, the praying mantis is a quadruped. In July 2005, in rural Turkey, scientists discovered five Kurdish siblings who had learned to walk on their hands and feet. Unlike chimpanzees, which ambulate on their knuckles, the Kurdish siblings walked on their palms, allowing them to preserve the dexterity of their fingers. Many people practitioners of parkour and freerunning and Georges Hébert's Natural Method, find benefit in quadrupedal movements to build full body strength. Kenichi Ito is a Japanese man famous for speed running on four limbs. Quadrupedalism is sometimes referred to as being on all fours, is observed in crawling by infants. BigDog is a dynamically stable quadruped robot created in 2005 by Boston Dynamics with Foster-Miller, the NASA Jet Propulsion Laboratory, the Harvard University Concord Field Station. By NASA JPL, in collaboration with University of California, Santa Barbara Robotics Lab, is RoboSimian, with emphasis on stability and deliberation.
It has been demonstrated at the DARPA Robotics Challenge. Bipedalism Orthograde posture Family may provide evolution clue - BBC News
Organ system
An organ system is a group of organs that work together as a biological system to perform one or more functions. Each organ system does a particular job in the body, is made up of certain tissues; these specific systems are studied in anatomy. They are present in many types of animals. Respiratory system: the organs used for breathing, the pharynx, bronchi and diaphragm. Digestive system: digestion and processing food with salivary glands, stomach, gallbladder, intestines and anus. Cardiovascular system: and channeling blood to and from the body and lungs with heart and blood vessels. Urinary system: kidneys, ureters and urethra involved in fluid balance, electrolyte balance and excretion of urine. Integumentary system: skin, hair and nails. Skeletally system: structural support and protection with bones, cartilage and tendons. Endocrine system: communication within the body using hormones made by endocrine glands such as the hypothalamus, pituitary gland, pineal gland, thyroid and adrenal glands.
Lymphatic system: the transfer of lymph between tissues and the blood stream. Includes the functions of immune responses and the development of antibodies. Our bodies consist of a number of biological systems that carry out specific functions necessary for everyday living; the job of the circulatory system is to move blood, oxygen, carbon dioxide, hormones, around the body. It consists of the heart, blood vessels and veins. Immune system: protects the organism from foreign bodies. Nervous system: collecting and processing information with brain, spinal cord, peripheral nervous system and sense organs. Sensory systems: visual system, auditory system, olfactory system, gustatory system, somatosensory system, vestibular system. Muscular system: allows for manipulation of the environment, provides locomotion, maintains posture, produces heat. Includes skeletal muscles, smooth muscles and cardiac muscle. Reproductive system: the sex organs, such as ovaries, fallopian tubes, vagina, mammary glands, testes, vas deferens, seminal vesicles and prostate
