"Chromosome 12 Chromosome 12 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 12 spans about 133 million base pairs (the building material of DNA) and represents between 4 and 4.5 percent of the total DNA in cells. Chromosome 12 contains the Homeobox C gene cluster. The following are some of the gene count estimates of human chromosome 12. Because researchers use different approaches to genome annotation their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction). Among various projects, the collaborative consensus"
"rib pair number 12. The first rib is the shortest, broadest, flattest, and most curved.<ref name=""Human Body Maps/Ribs""></ref> At birth the majority of humans have 33 separate vertebrae. However, during normal development several vertebrae fuse together, leaving a total of 24, in most cases. The confusion about whether or not there are 32-34 vertebrae stems from the fact that the two lowest vertebrae, the sacrum and the coccyx, are single bones made up of several smaller bones which have fused together. This is how the vertebrae are counted: 24 separate vertebrae and the sacrum, formed from 5 fused vertebrae and"
"ribs"" and ""false ribs"" describe rib pairs that are directly or indirectly attached to the sternum. The first seven rib pairs known as the ""fixed"" or vertebrosternal ribs are the ""true ribs"" () as they connect directly to the sternum; the next five pairs (eighth to twelfth) are the ""false ribs"" (), or vertebrochondral ribs as they connect indirectly to the sternum via the costal cartilages of the ribs above them. Their elasticity allows rib cage movement for respiratory activity. The phrase ""floating rib"" () refers to the two lowermost, the eleventh and twelfth rib pairs; so-called because they are"
"of this bone can be found above the level of the clavicle. Ribs 2 through 7 have a more traditional appearance and become longer and less curved as they progress downwards. The following five sets are known as ""false ribs"", three of these sharing a common cartilaginous connection to the sternum, while the last two (eleventh and twelfth ribs) are termed floating ribs. They are attached to the vertebrae only, and not to the sternum or cartilage coming off of the sternum. In general, human ribs increase in length from ribs 1 through 7 and decrease in length again through"
"Rib In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax. In some animals, especially snakes, ribs may provide support and protection for the entire body. Ribs are classed as flat bones which usually have a protective role in the body. Humans have 24 ribs, in 12 pairs. All are attached at the back to"
"a rib. There is also a facet on each of the transverse processes which articulates with the tubercle of a rib. The number of thoracic vertebrae varies considerably across the species. Most marsupials have thirteen, but koalas only have eleven. The norm is twelve to fifteen in mammals, (twelve in the human), though there are from eighteen to twenty in the horse, tapir, rhinoceros and elephant. In certain sloths there is an extreme number of twenty-five and at the other end only nine in the cetacean. There are fewer lumbar vertebrae in chimpanzees and gorillas, which have three in contrast"
"muscles, the rib cage makes up the thoracic wall and provides attachments for the muscles of the neck, thorax, upper abdomen, and back. The rib cage has a major function in the respiratory system. Ribs are described based on their location and connection with the sternum. All ribs are attached behind to the thoracic vertebrae and are numbered accordingly one to twelve. Ribs that articulate directly with the sternum are called ""true ribs"", whereas those that connect indirectly via cartilage are termed ""false ribs"". Floating ribs (eleven and twelve) are not attached to the sternum at all. The terms ""true"
"modification called tightlacing, which uses a corset to compress and move the ribs. The ribs, particularly their sternal ends, are used as a way of estimating age in forensic pathology, due to their progressive ossification. The number of ribs as 24 (12 pairs) was noted by the Flemish anatomist Vesalius in his key work of anatomy ""De humani corporis fabrica"" in 1543, setting off a wave of controversy, as it was traditionally assumed from the Biblical story of Adam and Eve that men's ribs would number one fewer than women's. In herpetology, costal grooves refer to lateral indents along the"
"of these early ribs have been lost, and in living amphibians and reptiles, there is great variation in rib structure and number. For example, turtles have only eight pairs of ribs, which are developed into a bony or cartilaginous carapace and plastron, while snakes have numerous ribs running along the full length of their trunk. Frogs typically have no ribs, aside from a sacral pair, which form part of the pelvis. In birds, ribs are present as distinct bones only on the thoracic region, although small fused ribs are present on the cervical vertebrae. The thoracic ribs of birds possess"
"a wide projection to the rear; this uncinate process is an attachment for the shoulder muscles. Usually dogs have 26 ribs. Mammals usually also only have distinct ribs on the thoracic vertebra, although fixed cervical ribs are also present in monotremes. In marsupials and placental mammals, the cervical and lumbar ribs are found only as tiny remnants fused to the vertebrae, where they are referred to as transverse processes. In general, the structure and number of the true ribs in humans is similar to that in other mammals. Unlike reptiles, caudal ribs are never found in mammals. Ribs as food"
"ribs. The sternum consists of multiple sternebrae, which fuse to form one bone, attached to the 8 ""true"" pairs of ribs, out of a total of 18. The vertebral column usually contains 54 bones: 7 cervical vertebrae, including the atlas (C1) and axis (C2) which support and help move the skull, 18 (or rarely, 19) thoracic, 5-6 lumbar, 5 sacral (which fuse together to form the sacrum), and 15-25 caudal vertebrae with an average of 18. Differences in number may occur, particularly in certain breeds. For example, some, though not all, Arabians, may have 5 lumbar vertebrae, opposed to the"
"Rib cage The rib cage is the arrangement of ribs attached to the vertebral column and sternum in the thorax of most vertebrates, that encloses and protects the heart and lungs. In humans, the rib cage, also known as the thoracic cage, is a bony and cartilaginous structure which surrounds the thoracic cavity and supports the shoulder girdle to form the core part of the human skeleton. A typical human rib cage consists of 24 ribs in 12 pairs, the sternum and xiphoid process, the costal cartilages, and the 12 thoracic vertebrae. Together with the skin and associated fascia and"
"attached only to the vertebrae–and not to the sternum or cartilage of the sternum. These ribs are relatively small and delicate, and include a cartilaginous tip. The spaces between the ribs are known as intercostal spaces; they contain the intercostal muscles, and neurovascular bundles containing the nerves, arteries, and veins. Each rib consists of a head, neck, and a shaft. All ribs are attached posteriorly to the thoracic vertebrae. They are numbered to match the vertebra they attach to – one to twelve, from top (T1) to bottom. The head of the rib is the end part closest to the"
"at this level. The tenth rib attaches directly to the body of vertebra T10 instead of between vertebrae like the second through ninth ribs. Due to this direct attachment, vertebra T10 has a complete costal facet on its body. The eleventh and twelfth ribs, the floating ribs, have a single articular facet on the head, which is of rather large size. They have no necks or tubercles, and are pointed at their anterior ends. The eleventh has a slight angle and a shallow costal groove, whereas the twelfth does not. The twelfth rib is much shorter than the eleventh rib,"
"rounded ends are attached at joints to the thoracic vertebrae at the back and the flattened ends come together at the sternum, in the front.<ref name=""Postcranial Skeletal/Ribs""></ref> The upper seven pairs of ribs attach to the sternum with costal cartilage and are known as “true ribs.” The 8th through 10th ribs have non-costal cartilage which connects them to the ribs above. The last two ribs are called “floating ribs” because they do not attach to the sternum or to other ribs and simply “hang free.” The length of each rib increases from number one to seven and then decreases until"
"the ribs. Expansion of the rib cage in males is caused by the effects of testosterone during puberty. Thus, males generally have broad shoulders and expanded chests, allowing them to inhale more air to supply their muscles with oxygen. Variations in the number of ribs occur. About 1 in 200-500 people have an additional cervical rib, and there is a female predominance. Intrathoracic supernumerary ribs are extremely rare. The rib remnant of the 7th cervical vertebra on one or both sides is occasionally replaced by a free extra rib called a cervical rib, which can mechanically interfere with the nerves"
"the thoracic vertebrae, and are numbered from 1–12 according to the vertebrae they attach to. The first rib is attached to thoracic vertebra 1 (T1). At the front of the body most of the ribs are joined by costal cartilages to the sternum. The ribs connect to the vertebrae with two joints, the costovertebral joints. The parts of a rib include the head, neck, body (or ""shaft""), tubercle, and angle. The head of the rib lies next to a vertebra. The ribs connect to the vertebrae with two costovertebral joints, one on the head and one on the neck. The"
"stomach. The bones of the thorax, called the ""thoracic skeleton"" is a component of the axial skeleton. It consists of the ribs and sternum.The ribs of the thorax are numbered in ascending order from 1-12. 11 & 12 are known as floating ribs because they have no anterior attachment point in particular the cartilage attached to the sternum, as 1-7 are, and therefore are termed ""floating"". Whereas ribs 8-10 are termed false ribs as their costal cartilage articulates with the costal cartilage of the rib above. The anatomy of the chest can also be described through the use of anatomical"
"the vertebral body itself, NOT for the part of the rib that they articulate with. Costal facets only apply to ribs 2-9. Ribs 1, 10, 11, and 12 articulate completely onto the thoracic vertebrae rather than in between two of them. Superior costal facet The superior costal facet (or superior costal fovea) is a site where a rib forms a joint with the top of a vertebra. Ribs connect to the thoracic vertebrae at two main points, the inferior and superior costal facets. These connection points are located on two different vertebrae that are located on top of one another."
"the skull passes through the pelvis and birth canal during birth. During development the eight separate plates of the immature bones fuse together into one single structure known as the Skull. The only bone that remains separate from the rest of the skull is the mandible.<ref name=""Inner Body/Skull""></ref> The rib cage is composed of 12 pairs of ribs plus the sternum for a total of 25 separate bones. The rib cage functions as protection for the vital organs such as the heart and lungs. The ribs are shaped like crescents, with one end flattened and the other end rounded. The"
"the longest is usually about , depending on the size of the hog. A pig side has 15 to 16 ribs (depending on the breed), but usually two or three are left on the shoulder when it is separated from the loin. So, a rack of back ribs contains a minimum of eight ribs (some may be trimmed if damaged), but can include up to 13 ribs, depending on how it has been prepared by the butcher. A typical commercial rack has 10–13 bones. If fewer than 10 bones are present, butchers call them ""cheater racks"". Rib tips are short,"
"the seventh, eighth, ninth, and tenth cartilages, respectively. The lateral end of each cartilage is continuous with the osseous tissue of the rib to which it belongs. The medial end of the first is continuous with the sternum; the medial ends of the six succeeding ones are rounded and are received into shallow concavities on the lateral margins of the sternum. The medial ends of the eighth, ninth, and tenth costal cartilages are pointed, and are connected each with the cartilage immediately above. Those of the eleventh and twelfth are pointed and free. In old age the costal cartilages are"
"rib 12. Along with this change in size, the ribs become progressively oblique (slanted) from ribs 1 through 9, then less slanted through rib 12. The rib cage is separated from the lower abdomen by the thoracic diaphragm which controls breathing. When the diaphragm contracts, the thoracic cavity is expanded, reducing intra-thoracic pressure and drawing air into the lungs. This happens through one of two actions (or a mix of the two): when the lower ribs the diaphragm connects to are stabilized by muscles and the central tendon is mobile, when the muscle contracts the central tendon is drawn down,"
"Bifid rib A bifid rib (bifurcated rib or sternum bifidum) is a congenital abnormality of the rib cage and associated muscles and nerves which occurs in about 1.2% of humans. Bifid ribs occur in up to 8.4% of Samoans. The sternal end of the rib is cleaved into two. It is usually unilateral. Bifid ribs are usually asymptomatic, and are often discovered incidentally by chest X-ray. Effects of this neuroskeletal anomaly can include respiratory difficulties, neurological difficulties, limitations, and limited energy from the stress of needing to compensate for the neurophysiological difficulties. Another association is with odontogenic keratocysts (OKC [a.k.a."
"by distinctly spaced, well-rounded, very regular, slightly retractively slanting axial ribs of which 18 occur upon the first five and 20 upon the remaining turns. These ribs become decidedly enfeebled and somewhat flattened toward the summit. The intercostal spaces are about twice as wide as the ribs crossed by 12 incised spiral lines of which the first to fourth, and the sixth, ninth, and tenth are mere striations while the fifth, seventh, eighth, eleventh, and twelfth are subequal and much stronger. The widest space is between the tenth and eleventh line, the rest of the spacing is subequal, excepting the"
"to this on the body whorl. Of these ribs 10 occur upon the first to fourth, 12 upon the fifth to seventh, and 14 upon the penultimate whorl. The axial ribs are about as wide as the spaces that separate them. In addition to these axial ribs the whorls are marked by numerous slender spiral threads, of which about 5 occur in the area of the sinus on the last three turns. These are finer than those that cover the rest of the turn between the sutures. Of the latter, three occur on the first to third, four on the"
"rib, which on the penultimate equals in size the posterior rib. In addition to these, there are two or three spiral threads between the subcentral and posterior rib, and a like number between the latter and suture. On the body whorl there are three spiral ribs in front of the aperture, usually less distinct as they approach the outer lip, and with one or two threads in the interspaces. Anterior to this are ten or eleven small spirals, somewhat irregular in size. Above the sinus are seven or eight threads, two of which are slightly stronger, and in some examples"
"the scalene tubercle. The ""anterior extremity"" is larger and thicker than that of any of the other ribs. The second rib is the second uppermost rib in humans or second most frontal in animals that walk on four limbs. In humans, the second rib is defined as a true rib since it connects with the sternum through the intervention of the costal cartilage anteriorly (at the front). Posteriorly, the second rib is connected with the vertebral column by the second thoracic vertebra. The second rib is much longer than the first rib, but has a very similar curvature. The non-articular"
"from the first to the seventh, then gradually decrease to the twelfth. Their breadth, as well as that of the intervals between them, diminishes from the first to the last. They are broad at their attachments to the ribs, and taper toward their sternal extremities, excepting the first two, which are of the same breadth throughout, and the sixth, seventh, and eighth, which are enlarged where their margins are in contact. They also vary in direction: the first descends a little to the sternum, the second is horizontal, the third ascends slightly, while the others are angular, following the course"
"of the lower of the two vertebrae to which the head is connected. The non-articular portion is a rough elevation and affords attachment to the ligament of the tubercle. The tubercle is much more prominent in the upper ribs than in the lower ribs. The first seven sets of ribs, known as ""true ribs"", are attached to the sternum by the costal cartilages. The first rib is unique and harder to distinguish than other ribs. It is a short, flat, C-shaped bone. The vertebral attachment can be found just below the neck at the first thoracic vertebra, and the majority"
"Cervical rib A cervical rib in humans is an extra rib which arises from the seventh cervical vertebra. Sometimes known as ""neck ribs"", their presence is a congenital abnormality located above the normal first rib. A cervical rib is estimated to occur in 0.2% (1 in 500 people) to 0.5% of the population. People may have a cervical rib on the right, left or both sides. Most cases of cervical ribs are not clinically relevant and do not have symptoms; cervical ribs are generally discovered incidentally. However, they vary widely in size and shape, and in rare cases, they may"
"the ribs is somewhat variable, especially on the anterior whorls, where they are occasionally only just visible. The ribs are traversed by comparatively coarse and fine spiral threads. Of these there are four to six coarser and more prominent than the rest, situated in the anterior two-thirds of each whorl, especially prominent where they cross the ribs, more numerous, amounting to about eight or nine, on the body whorl, with much broader interspaces between each of which has a medial finer thread with a pair of still tiner threads on either side of it. The posterior third is occupied by"
"they possess. The number in non-passerines generally varies between 9 and 11, but grebes, storks and flamingos have 12, and ostriches have 16. While most modern passerines have ten primaries, some have only nine. Those with nine are missing the most distal primary (sometimes called the remicle) which is typically very small and sometimes rudimentary in passerines. The outermost primaries—those connected to the phalanges—are sometimes known as pinions. Secondaries are connected to the ulna. In some species, the ligaments that bind these remiges to the bone connect to small, rounded projections, known as quill knobs, on the ulna; in other"