In mammals, the thorax is the region of the body formed by the sternum, the thoracic vertebrae, and the ribs. It extends from the neck to the diaphragm, and does not include the upper limbs. The heart and the lungs reside in the thoracic cavity, as well as many blood vessels. The inner organs are protected by the rib cage and the sternum. Thoracic vertebrae are also distinguished in birds, but not in reptiles.
In tetrapods
Thorax
Thorax | In tetrapods
The heart and the lungs reside in the thoracic cavity, as well as many blood vessels; inner organs are protected by the rib cage and the sternum. In mammals, the thorax is the region of the body formed by the sternum, the thoracic vertebrae, and the ribs. Thoracic vertebrae are also distinguished in birds, but not in reptiles. Thoracic vertebrae are also distinguished in birds, but not in reptiles. It is the region of the body formed by the sternum, the thoracic vertebrae, and the ribs. It extends from the neck to the diaphragm, and does not include the upper limbs.
what is ypresiomyrma?
user
It is an extinct genus of ants in the subfamily Myrmeciinae.
assistant
how are they classified?
user
As "incertae sedis"
assistant
who described them for thr first time?
user
Bruce Archibald, Stefan Cover and Corrie Moreau
assistant
who is the first person?
user
Sorry. I cannot find the answer based on the context.
assistant
how do they look like?
user
The waist connecting the thorax and the abdomen is composed of a single segment, the head is in various shapes, and mandibles are a distinct triangular shape and shorter than the head.
assistant
what is thorax?
user
It is the part of the anatomy of humans, mammals, other tetrapod animals located between the neck and the abdomen.
assistant
from where did it get its name?
user
The word comes from the Greek θώραξ "thorax" "breastplate, cuirass, corslet.
assistant
how does one experience pain in this part of the body?
user
Cardiac arrest - feelings of sudden pressure in the chest or a crushing pain in the back, neck, and arms; noncardiac issues - burning feeling along the digestive tract or pain when deep breaths are attempted.
assistant
how is its structure?
user
Humans and hominids - the chest region of the body between the neck and the abdomen, along with its internal organs and other contents; protected and supported by the rib cage, spine, and shoulder girdle.
assistant
what are the injuries one can have in this part of the body?
user
Major pathophysiologies encountered in blunt chest trauma involve derangements in the flow of air, blood, or both in combination.
assistant
how is this part of the body in arthropods?
user
It is the area where the wings and legs attach in insects, or an area of multiple articulating plates in trilobites.
assistant
and in tetrapods?
user
In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the creature's body, each of which is in turn composed of multiple segments. It is the area where the wings and legs attach in insects, or an area of multiple articulating plates in trilobites. In most insects, the thorax itself is composed of three segments; the prothorax, the mesothorax, and the metathorax. In extant insects, the prothorax never has wings, though legs are always present in adults; wings (when present) are restricted to at least the mesothorax, and typically also the metathorax, though the wings may be reduced or modified on either or both segments.
Thorax | In arthropods
The thorax is the midsection (tagma) of the insect body. It holds the head, legs, wings and abdomen. It is also called mesosoma or cephalothorax in other arthropods. It is formed by the prothorax, mesothorax and metathorax and comprises the scutellum; the cervix, a membrane that separates the head from the thorax; and the pleuron, a lateral sclerite of the thorax. In dragonflies and damselflies the mesothorax and metathorax are fused together to form the synthorax.
Thorax (arthropod anatomy) | Introduction
In mammals, the thorax is the region of the body formed by the sternum, the thoracic vertebrae, and the ribs. It extends from the neck to the diaphragm, and does not include the upper limbs. The heart and the lungs reside in the thoracic cavity, as well as many blood vessels. The inner organs are protected by the rib cage and the sternum. Thoracic vertebrae are also distinguished in birds, but not in reptiles.
Thorax | In tetrapods
The thorax is composed of three segments, each of which bears a single pair of legs. As is typical of arthropods adapted to life on land, each leg has only a single walking branch composed of five segments, without the gill branches found in some other arthropods and with gill on the abdominal segments of some immature aquatic insects. In most insects the second and third thoracic segments also support wings. It has been suggested that these may be homologous to the gill branches of crustaceans, or they may have developed from extensions of the segments themselves.
Hexapoda | Morphology
The thorax is a series of articulated segments that lie between the cephalon and pygidium. The number of segments varies between 2 and 103 with most species in the 2 to 16 range. Each segment consists of the central axial ring and the outer pleurae, which protected the limbs and gills. The pleurae are sometimes abbreviated or extended to form long spines. Apodemes are bulbous projections on the ventral surface of the exoskeleton to which most leg muscles attached, although some leg muscles attached directly to the exoskeleton. Determining a junction between thorax and pygidium can be difficult and many segment counts suffer from this problem.
Trilobite | Thorax
Some zoologists consider the thorax to consist of the two regions with appendages, and the abdomen the region without appendages. Others believe the region of fused segments to be part of the abdomen. For clarity, this article uses "thorax" to mean the two body regions with limbs.
Triops longicaudatus | Structure
The part of the skeleton that is ‘tucked under’ (the doublure) has no sutures crossing it to form a rostral plate.The thorax has 11 (rarely 10) segments, the side lobes (or pleurae) are furrowed, and the articulating facets distinct.
Phacopina | Description
The thorax reaches its greatest width at the 6th segment. The frontal part or prothorax consists of 6 segments, with number 5 and 6 fused, and the 6th carrying very large trailing spines. The rear part or opistothorax consists of a variable but extremely large number of segments (up to 97).
Emuellidae | Introduction
In the Apocritan Hymenoptera, the first abdominal segment is fused to the metathorax, where it forms a structure known as the propodeum. Accordingly, in these insects, the functional thorax is composed of four segments, and is therefore typically called the mesosoma to distinguish it from the "thorax" of other insects. Each thoracic segment in an insect is further subdivided into various parts, the most significant of which are the dorsal portion (the notum), the lateral portion (the pleuron; one on each side), and the ventral portion (the sternum). In some insects, each of these parts is composed of one to several independent exoskeletal plates with membrane between them (called sclerites), though in many cases the sclerites are fused to various degrees.
Thorax | In arthropods
It is variable in form and may be fused dorsally with some of the thoracic segments or occasionally be in two parts, hinged dorsally. Typically, each of the thoracic appendages is biramous and the endopods are the better developed of the branches, being used for crawling or grasping. Each endopod consist of seven articulating segments; the coxa, basis, ischium, merus, carpus, propodus and dactylus. In decapods, the claw is formed by the articulation of the dactylus against an outgrowth of the propodus. In some taxa, the exopods are lost and the appendages are uniramous. There is a clear demarcation between the thorax and the six or seven-segmented abdomen.
Malacostraca | Tagmata
Fuxianhuiids possess specialized post-antennal appendages with serrated edges used for food processing. In most fuxianhuiids, the thorax tergites narrow posteriorly, terminating in either a swimming paddle or paired flukes with a tailspine. In members of Fuxianhuiidae the thorax is divided into two sections, the anterior wide opisthothorax and the posterior narrow limbless tail-like abdomen. Many specimens are known with exceptional soft tissue preservation, including preserved guts and neural tissue, which given their basal phylogenetic position makes them important in understanding the evolution of arthropoda as a whole.
Fuxianhuiida | Introduction
The third pereiopod or thoracic leg is particularly stout and has a curved propodus (penultimate joint) and powerful dactylus (claw); the fourth pereiopod is smaller; in males, these two legs have long, plumose setae (bristles). The basal segments of the first three pleopods or abdominal legs are much enlarged. The abdomen ends in a short telson, cleft for three quarters of its length, which is flanked by uropods to form a tail fan.
Nototropis falcatus | Description
Ventrally, a large plate has been interpreted as a hypostome. The head shield overlaps a tapering series of 12–17 trunk tergites, which lead into a set of limb-bearing segments comprising the thorax. The limbs are simple in form, consisting of a smooth oval exopod and a stout, annulated endopod. There is no one-to-one correspondence between the thoracic tergites and the limbs, but, rather, there appear to be two or three limbs per tergite. Behind the thorax is a narrower abdominal region, consisting of 14 tergites, that bears no appendages. The abdomen is terminated by a telson-like spine.
Fuxianhuia | Description
Coelurosaurian theropods are the notable exception to the pattern of body size increases.
Tetanurae | Body Size
It extended far dorsally and was joined to the backbone by one or more specialized sacral ribs. The hind legs were somewhat specialized in that they not only supported weight, but also provided propulsion. The dorsal extension of the pelvis was the ilium, while the broad ventral plate was composed of the pubis in front and the ischium in behind. The three bones met at a single point in the center of the pelvic triangle called the acetabulum, providing a surface of articulation for the femur.
Tetrapod | Girdles
The anterior thorax consists of eleven segments, each bearing a pair of appendages, called thoracopods or pereiopods. None of the thoracopods are modified into maxillipeds for feeding. The posterior thorax consists of 16–25 segments, incompletely separated to form "rings". Each ring may consist of as many as six fused segments and bear up to six pairs of appendages (there are 54–66 limbs altogether). Most of the thoracic appendages resemble each other, but the first eleven pairs are best developed. There is a slight tendency to regional specialization and the first pair of legs is unlike the rest. It is an elongated, cheliped-like structure with a sensory function, while all the other appendages aid in feeding, respiration, and locomotion.
Triops longicaudatus | Thorax
The head is incapable of rotating laterally. Two pairs of antennae are set at the front of the head. The eyes are usually well developed and the mouthparts do not form a suctorial cone or proboscis. The thorax or pereon is smooth or slightly sculptured and sometimes spinose or rugose. A flexion occurs between it and the abdomen or pleon, so from a lateral view, the front part of the animal is arched up. The pereiopods are held close to the head, while the pleopods are attached to the pleon, making it appear no appendages on the pereon.
Arcturidae | Description
The thorax consists of six short but wide segments, the outline of which is a continuation of the cheeks. The axis is narrow, less than ⅓× as wide as each of the ribs (or pleurae) to its sides. The tailshield, termed pygidium, is small, approximately wide triangular, with the axis narrow triangular, reaching the border. The axial rings and ribs become less conspicuous further to the back.
Trinucleidae | Description
Between the ungues a median unguitractor plate supports the pretarsus. The plate is attached to the apodeme of the flexor muscle of the ungues. In the Neoptera the parempodia are a symmetrical pair of structures arising from the outside (distal) surface of the unguitractor plate between the claws. It is present in many Hemiptera and almost all Heteroptera. Usually the parempodia are bristly (setiform), but in a few species they are fleshy. Sometimes the parempodia are reduced in size so as to almost disappear. Above the unguitractor plate the pretarsus expands forward into a median lobe, the arolium. Webspinners (Embioptera) have an enlarged basal tarsomere on each of the front legs, containing the silk-producing glands.
Arthropod leg | Tarsus
In these orders, there is also typically a small sclerite attached to the mesonotum that covers the wing base, called the tegula. In one group of insects, the Hemiptera, the dorsal surface of the thorax is typically formed primarily of the prothorax, but also in part by the enlarged posterior portion of the mesonotum, called the scutellum; in the Coleoptera, the scutellum may or may not be visible, usually as a small triangular plate between the elytral bases, thus similar in position to the Hemipteran scutellum. In Diptera and Hymenoptera the mesothoracic scutellum is also distinct, but much smaller than the mesoscutum.
Mesothorax | Introduction
Hardened plates in the exoskeleton are called sclerites. Sclerites may be simple protective armour, but also may form mechanical components of the exoskeleton, such as in the legs, joints, fins or wings. In the typical body segment of an insect or many other Arthropoda, there are four principal regions. The dorsal region is the tergum; if the tergum bears any sclerites, those are called "tergites". The ventral region is called the sternum, which commonly bears sternites. The two lateral regions are called the pleura (singular pleurum) and any sclerites they bear are called pleurites.
Arthropod cuticle | Morphology
The thorax or chest is a part of the anatomy of humans, mammals, other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the creature's body, each of which is in turn composed of multiple segments. The human thorax includes the thoracic cavity and the thoracic wall. It contains organs including the heart, lungs, and thymus gland, as well as muscles and various other internal structures. Many diseases may affect the chest, and one of the most common symptoms is chest pain.
Thorax | Introduction
The thorax constitutes a large portion of the insect's body. As in all insects, it is composed of three segments: the prothorax, mesothorax, and metathorax. Each section "contains one pair of legs, however, the wings are found only on the mesothoracic and metathoracic segments."
Idolomantis diabolica | Thorax
The thorax has at least 20 segments. The tail shield (or pygidium) is small.
Nepeidae | Introduction
Antennae, head, thorax and abdomen much as in the male.
Prosotas nora | Description
In primitive tetrapods, such as "Trematops", the tarsus consists of three rows of bones. There are three proximal tarsals, the tibiale, intermedium, and fibulare, named for their points of articulation with the bones of the lower limb. These are followed by a second row of four bones, referred to as the centralia (singular: centrale), and then a row of five distal tarsals, each articulating with a single metatarsal. In the great majority of tetrapods, including all of those alive today, this simple pattern is modified by the loss and fusion of some of the bones. In reptiles and mammals, there are normally just two proximal tarsals, the calcaneus (equivalent to the amphibian fibulare) and the talus (probably derived from a fusion of multiple bones).
Tarsus (skeleton) | Other animals
In general, however, they have three pairs of thoracic legs, each ending in two claws. The abdomen often has adhesive discs on the last two segments.
Neuroptera | Anatomy and biology
Arthropods comprise the largest phylum in the animal kingdom with over a million known invertebrate species. Insects possess segmented bodies supported by a hard-jointed outer covering, the exoskeleton, made mostly of chitin. The segments of the body are organized into three distinct parts, a head, a thorax and an abdomen. The head typically bears a pair of sensory antennae, a pair of compound eyes, one to three simple eyes (ocelli) and three sets of modified appendages that form the mouthparts. The thorax has three pairs of segmented legs, one pair each for the three segments that compose the thorax and one or two pairs of wings.
Anatomy | Arthropod anatomy
The thorax is segmented into the two discernible parts, the pro- and pterothorax. The pterothorax is the fused meso- and metathorax, which are commonly separated in other insect species, although flexibly articulate from the prothorax. When viewed from below, the thorax is that part from which all three pairs of legs and both pairs of wings arise. The abdomen is everything posterior to the thorax. When viewed from above, most beetles appear to have three clear sections, but this is deceptive: on the beetle's upper surface, the middle section is a hard plate called the pronotum, which is only the front part of the thorax; the back part of the thorax is concealed by the beetle's wings.
Beetle | Thorax
The articulating middle part of the body (or thorax) has 12 segments. The axis is convex, and less than ½× as wide as each of the so-called pleurae to its sides. Segments pointed sideways with a rounded front (a shape called falcate). The tailshield (or pygidium) is about ½× as wide as the cephalon, almost twice as wide as long, excluding the two, widely spaced spines. These are at an angle of approximately 30° with the rest body. The axis in the pygidium is 1¼× longer than wide, with almost parallel sides, almost reaching the rear margin, with 3 or 4 axial rings; 3 sets of interpleural grooves and pleural furrows ending at distance of the margin.
Tricrepicephalus | Description
The thorax of most anostracans has 13 segments (19 in "Polyartemiella" and 21 in "Polyartemia"). All but the last two are very similar, with a pair of biramous phyllopods (flattened, leaf-like appendages). The last two segments are fused together, and their appendages are specialised for reproduction. Most anostracans have separate sexes (gonochorism), but a few reproduce by parthenogenesis. The abdomen comprises 6 segments without appendages, and a telson, which bears two flattened caudal rami or "cercopods".
Anostraca | Thorax and abdomen
Similarly, in the Tetrigidae, the pronotum is extended backward to cover the flight wings, supplanting the function of the tegmina.
Prothorax | Introduction
The free cheeks curve strongly downwards and have prominent borders, particularly to the side and the back, and these bear long tube- or blade-like genal spines. The articulating middle part of the body (or thorax) consists of 9 or 10 segments. The axis is extremely convex and the side-lobes (or pleurae) are narrow. The tailshield (or pygidium) is convex and its axis is prominent and has 2-4 rings. The most backward piece may bear a long spine. The seam of the exoskeleton (or doublure) is narrow.
Telephinidae | Description
In tetrapod anatomy, "leg" is used to refer to the entire limb. In human medicine the precise definition refers only to the segment between the knee and the ankle. This lower segment is also called the "shank", and the front (anterior) of the segment is called the "shin" or "pretibia". In bipedal tetrapods, the two lower limbs are referred to as the "legs" and the two upper limbs as "arms" or "wings" as the case may be.
Leg | Tetrapod legs
If pygidial spines are lacking, the margin is gradually rounded. The thorax has 12 segments.
Dikelocephalus | Introduction
The first pair of pereiopods (legs) is armed with a large, asymmetric pair of claws. The larger one is the "crusher", and has rounded nodules used for crushing prey; the other is the "cutter", which has sharp inner edges, and is used for holding or tearing the prey. Depending on whether the crusher claw is on the left side or right side of its body determines whether they are left or right handed.
American lobster | Thorax
Palpebral lobes are short and of variable length. Hypostoma in some species is fused with the rostral plate, e.g. in "Paradoxides davidis" Salter (1863, "op. cit."), a character that distinguishes the genus from all other trilobites, except in some Cambrian Corynexochida such as "Oryctocephalus" and "Fieldaspis". Thorax consists of 19-21 segments; axis about as wide as each of the pleurae, excluding pleural spines which curve backwards and slightly increase in length towards posterior. Spines on rear thoracic segment twice as long, oftem more, than associated pleurae and extending well beyond the pygidium. Pygidium is small with one or two axial rings and may be partially or completely fused to the last thoracic segment.
Paradoxides | Description
During moulting, the exoskeleton generally splits between the head and thorax, which is why so many trilobite fossils are missing one or the other. In most groups facial sutures on the cephalon helped facilitate moulting. Similar to lobsters and crabs, trilobites would have physically "grown" between the moult stage and the hardening of the new exoskeleton.
Trilobite | Terminology
They are called pleopods. There is one final pair called uropods, which, with the telson, form the tail fan.
Decapoda | Anatomy
The oval abdomen is longer than it is wide and has a generally teardrop shape. The thorax hosts two sets of horn-like protrusions, giving it an uneven outline with the larger "horns" placed to the rear.
Pseudogarypus synchrotron | Description
The thorax has 17 to 23 segments, gradually diminishing in size. The pleural spines are long and sickle-shaped. The tailshield (or pygidium) is very small and subquadrate in shape.
Nevadella | Description
Tardigrades lack several Hox genes and a large intermediate region of the body axis. In insects, this corresponds to the entire thorax and the abdomen. Practically the whole body, except for the last pair of legs, is made up of just the segments that are homologous to the head region in arthropods. All adult tardigrades of the same species have the same number of cells (see eutely). Some species have as many as 40,000 cells in each adult, while others have far fewer.
Tardigrade | Anatomy and morphology
In the tetrapod, the front of the skull lengthened, positioning the orbits farther back on the skull.
Tetrapod | Skull
The thorax is barely wider than the head and the forelegs are smaller than the mid and hindlegs. The abdomen is wider than the thorax, and it bears six spiracles on each side. Nymphs have a head that has a broadly rounded anterior margin and lacks a lateral notch anterior to the antennae. Its thorax is slightly wider than its head, with gently convex lateral margins. The most basal segment, or coxae, are subtriangular. Their abdomen has nine rows of two-dorsal central abdominal seta and one fairly long dorsal lateral abdominal seta.
Lemurpediculus verruculosus | Morphology
In most tetrapods, the articular bone forms the lower portion of the jaw joint. The upper jaw articulates at the quadrate bone.
Articular bone | In amphibians and reptiles
The prothorax is the simplest and smallest of the three segments while the mesothorax is the most developed. Between the head and thorax is the membranous neck or "cervix". It comprises a pair of lateral cervical sclerites and is composed of both cephalic and thoracic elements. Between the head and the thorax is a tufted scale called the pronotum. On either side is a shield-like scale called a scapula. In the Noctuoidea, the metathorax is modified with a pair of tympanal organs.
External morphology of Lepidoptera | Thorax
The scutellum (Latin for 'little shield', the hard extension of the thorax covering the abdomen in hemipterans) is triangular and does not cover the leathery middle section of the forewing but is often partially covered by the prothorax. The tarsi (the final segments of the legs) have 2 to 3 segments. They are most reliably distinguished from pentatomids by having six exposed abdominal spiracles instead of five.
Tessaratomidae | Description
Like in many early trilobites, the thorax of "Paradoxides" consists of so-called nonfulcrate segments, that allow the animal to roll, providing protection from front, rear, top, and bottom, while leaving access to the soft ventral side of the animal from each of the sides. Complete specimens of "Paradoxides" have been found with the librigenae and fused rostral-hypostomal plate. In moulting, the body was arched above the substrate, with the anterior border at the front and posterior pleural spines dug into sediment. Stretching the body would then result in rupturing the sutures in the cephalon and flipping off the librigenae including the rostral-hypostomal plate.
Paradoxides | Behaviour
Most Artiopods are broadly similar in morphology to trilobites, possessing a dorsoventrally compressed body, with a trunk composed of between 6 and 19—generally 10 to 12—articulated segments, most of which contain wide pleurae. These pleurae are absent in the posteriormost segment, which bears a pair of non-walking appendages, and may be absent in the two or three posteriormost segments in rare cases. The appendage-bearing segment is fused to the telson in certain members of Artiopoda, including some aglaspidids, which may have secondarily lost the appendages.
Artiopoda | Description
In typical early tetrapod posture, the upper arm and upper leg extended nearly straight horizontal from its body, and the forearm and the lower leg extended downward from the upper segment at a near right angle. The body weight was not centered over the limbs, but was rather transferred 90 degrees outward and down through the lower limbs, which touched the ground. Most of the animal's strength was used to just lift its body off the ground for walking, which was probably slow and difficult. With this sort of posture, it could only make short broad strides. This has been confirmed by fossilized footprints found in Carboniferous rocks.
Tetrapod | Locomotion
The articulated middle part of the body (or thorax) has 7-11 segments (9 in "A. wheeleri"), with rounded tips. The tailshield (or pygidium) is about 30% of the body length, is semi-circular in shape, with a wide flat border, and an entire margin.
Asaphiscus | Description
The seven free segments of the thorax each bear a pair of unbranched pereopods (limbs). In most species these are used for locomotion and are of much the same size, morphology and orientation, giving the order its name "Isopoda", from the Greek "equal foot". In a few species, the front pair are modified into gnathopods with clawed, gripping terminal segments. The pereopods are not used in respiration, as are the equivalent limbs in amphipods, but the coxae (first segments) are fused to the tergites (dorsal plates) to form epimera (side plates). In mature females, some or all of the limbs have appendages known as oostegites which fold underneath the thorax and form a brood chamber for the eggs.
Isopoda | Description
The body of an amphipod is divided into 13 segments, which can be grouped into a head, a thorax and an abdomen. The head is fused to the thorax, and bears two pairs of antennae and one pair of sessile compound eyes. It also carries the mouthparts, but these are mostly concealed. The thorax and abdomen are usually quite distinct and bear different kinds of legs; they are typically laterally compressed, and there is no carapace. The thorax bears eight pairs of uniramous appendages, the first of which are used as accessory mouthparts; the next four pairs are directed forwards, and the last three pairs are directed backwards.
Amphipoda | Anatomy
The fossils of the moults of trilobites can often be told from the fossils of the actual animals by whether the librigena are present. (The librigena, or cheek spines, detach during moulting.) In ptychopariids, short bladelike genal spines are often present on the tips of the librigena. The thorax is large and is typically made up of eight or more segments. The thorax is usually much longer than the pygidium, which is usually small. In some species the pygidium is outlined with a flat border.
Ptychopariida | Introduction
In some species, this region is modified and assumes a different name. The thorax is a tagma composed of three sections, the prothorax, mesothorax and the metathorax. The anterior segment, closest to the head, is the prothorax, with the major features being the first pair of legs and the pronotum. The middle segment is the mesothorax, with the major features being the second pair of legs and the anterior wings. The third and most posterior segment, abutting the abdomen, is the metathorax, which features the third pair of legs and the posterior wings. Each segment is dilineated by an intersegmental suture.
Insect | Segmentation
At the end of the pleon is the tail fan, comprising a pair of biramous uropods and the telson, which bears the anus. Together, they are used for steering while swimming, and in the caridoid escape reaction. In crabs and some other carcinised decapods, the abdomen is folded under the cephalothorax.
Decapod anatomy | Telson
The metathorax is the posterior of the three segments in the thorax of an insect, and bears the third pair of legs. Its principal sclerites (exoskeletal plates) are the metanotum (dorsal), the metasternum (ventral), and the metapleuron (lateral) on each side. The metathorax is the segment that bears the hindwings in most winged insects, though sometimes these may be reduced or modified, as in the flies (diptera), in which they are reduced to form halteres, or flightless, as in beetles (coleoptera), in which they may be completely absent even though forewings are still present. All adult insects possess legs on the metathorax.
Metathorax | Introduction
Joining the head to the thorax is a short neck. The thorax in all insects consists of three segments. These segments are clearly visible along the back of the wētā. Each segment of the thorax bears a pair of legs. The wētā does not have wings attached to its thorax.
Deinacrida elegans | Thorax
Even in an agnostid, with only 2 articulating thoracic segments, the process of enrollment required a complex musculature to contract the exoskeleton and return to the flat condition.
Trilobite | Volvation
The shoulder girdle was disconnected from the skull, resulting in improved terrestrial locomotion. The early sarcopterygians' cleithrum was retained as the clavicle, and the interclavicle was well-developed, lying on the underside of the chest. In primitive forms, the two clavicles and the interclavical could have grown ventrally in such a way as to form a broad chest plate. The upper portion of the girdle had a flat, scapular blade (shoulder bone), with the glenoid cavity situated below performing as the articulation surface for the humerus, while ventrally there was a large, flat coracoid plate turning in toward the midline. The pelvic girdle also was much larger than the simple plate found in fishes, accommodating more muscles.
Tetrapod | Girdles
The following orders are represented in the formation; Ephemeroptera, Odonata, Plecoptera, Blattodea, Orthoptera, Hemiptera, Neuroptera, Coleoptera, Hymenoptera, and Diptera.
Tiaojishan Formation | <a href="Arthropod">Arthropod</a>s (excluding <a href="crustacean">crustacean</a>s)
The mesothorax is the middle of the three segments in the thorax of an insect, and bears the second pair of legs. Its principal sclerites (exoskeletal plates) are the mesonotum (dorsal), the mesosternum (ventral), and the mesopleuron (lateral) on each side. The mesothorax is the segment that bears the forewings in all winged insects, though sometimes these may be reduced or modified, as in beetles (Coleoptera) or Dermaptera, in which they are sclerotized to form the elytra ("wing covers"), and the Strepsiptera, in which they are reduced to form halteres. All adult insects possess legs on the mesothorax. In some groups of insects, the mesonotum is hypertrophied, such as in Diptera, Hymenoptera, and Lepidoptera), in which the anterior portion of the mesonotum (called the mesoscutum, or simply "scutum") forms most of the dorsal surface of the thorax.
Mesothorax | Introduction
The pectoral (shoulder) girdle was robust. The cleithrum was long and blade-like, the scapulocoracoid was shaped like a reversed B, and the interclavicle was lozenge-shaped as in other early tetrapods and stem-tetrapods. The clavicles were unusually shaped, with a curved lower portion continuous with a tapering upper blade. The angle of curvature at the lower portion ranges from 45 degrees in the smallest specimen (UMZC 1285), to ~ 30 degrees in the holotype. The humerus (forearm bone) is flat and irregularly shaped, similar to the "L-shaped" humeri of most early tetrapods and stem-tetrapods (particularly "Baphetes"), but not the thinner, hourglass-shaped humeri of temnospondyls and amniote relatives.
Eucritta | Postcranial skeleton
In more derived tetrapods the dermal part of the girdle was gradually reduced and the scapulocoracoid split into a dorsal scapula and a ventral coracoid.
Shoulder girdle | Other animals
In females, the eleventh pair of legs is modified into brood pouches. The many legs posterior to the eleventh pair move the spent feeding and respiratory currents away.
Triops longicaudatus | Thorax
While most early tetrapods have slanted haemal spines which are positioned between the vertebrae, the haemal spines of nectrideans are completely vertical in orientation and fused to the pleurocentra, directly opposite the neural spines. Both the neural spines and haemal spines of the tail are characteristically fan-shaped. As a whole, nectrideans have rather short bodies and long and paddle-like tails, designed for swimming.
Nectridea | Vertebrae
The two lateral regions are called the pleura (singular: pleuron), and the ventral aspect is called the sternum. In turn, the notum of the prothorax is called the pronotum, the notum for the mesothorax is called the mesonotum and the notum for the metathorax is called the metanotum. Continuing with this logic, there is also the mesopleura and metapleura, as well as the mesosternum and metasternum. The tergal plates of the thorax are simple structures in apterygotes and in many immature insects, but are variously modified in winged adults. The pterothoracic nota each have two main divisions: the anterior, wing-bearing alinotum and the posterior, phragma-bearing postnotum.
Insect morphology | Thorax
As with most early trilobites, the Olenellina have an almost flat exoskeleton, that is only thinly calcified, and have crescent-shaped eye ridges. The suborder differs from all other trilobites by the lack of dorsal sutures in the head shield (or cephalon). There is a ventral mouth plate (or conterminant hypostome) with a very wide rostral plate extending between genal angles, with a perrostral suture (no connective sutures). The thorax may be composed of a prothorax that generally has 14 or 15 segments, and an opisthothorax that has between 0 and up to 34 segments. In segment 3, the areas right and left of the axis (or pleural lobes) are often enlarged, sometimes carrying large trailing pleural spines.
Olenellina | Description
The carapace grows from the thorax to cover the cephalothorax, and extends forwards between the eyes into a rostrum. This is only as long as the stalked eyes in Benthesicymidae, Luciferidae and Sergestidae, but considerably longer in Aristeidae. As well as the three pairs of maxillipeds, the thorax also bears five pairs of pereiopods, or walking legs; the first three of these end in small claws. The last two pereiopods are absent in Luciferidae and "Acetes", but much longer than the preceding pereiopods in "Hymenopenaeus" and "Xiphopenaeus". The thoracic appendages carry gills, which are protected beneath the carapace. The gills are typically branched, and so resemble trees, lending the group its scientific name, Dendrobranchiata, from the Greek words (', tree) and (', gills).
Dendrobranchiata | Thorax
The front segment of the thorax (prothorax) carries a pair of legs, and the synthorax carries the middle and rear legs and both pairs of wings. A dark stripe (humeral stripe) often follows the humeral suture, which runs from the base of the front wing towards the base of the middle leg. A paler antehumeral stripe is often found above the humeral stripe.
External morphology of Odonata | Thorax
In humans and other hominids, the thorax is the chest region of the body between the neck and the abdomen, along with its internal organs and other contents. It is mostly protected and supported by the rib cage, spine, and shoulder girdle.
Thorax | Structure
Phragmata (singular: phragma) are plate-like apodemes that extend inwards below the antecostal sutures, marking the primary intersegmental folds between segments; phragmata provide attachment for the longitudinal flight muscles. Each alinotum (sometimes confusingly referred to as a "notum") may be traversed by sutures that mark the position of internal strengthening ridges, and commonly divides the plate into three areas: the anterior prescutum, the scutum, and the smaller posterior scutellum. The lateral pleural sclerites are believed to be derived from the subcoxal segment of the ancestral insect leg. These sclerites may be separate, as in silverfish, or fused into an almost continuous sclerotic area, as in most winged insects.
Insect morphology | Thorax
The thorax, which develops from segments 2, 3, and 4 of the larva, consists of three invisibly divided segments, namely prothorax, metathorax, and mesothorax. The organs of insect locomotion – the legs and wings – are borne on the thorax. The forelegs spring from the prothorax, the forewings and middle pair of legs are borne on the mesothorax, and the hindwings and hindlegs arise from the metathorax. In some cases, the wings are vestigial. The upper and lower parts of the thorax (terga and sterna respectively) are composed of segmental and intrasegmental sclerites which display secondary sclerotisation and considerable modification in the Lepidoptera.
External morphology of Lepidoptera | Thorax
The abdomen ends in a telson and a pair of long, thin, multi-articulate caudal rami. The form of the telson varies between the two genera: in "Lepidurus", a rounded projection extends between the caudal rami, while in "Triops" there is no such projection.
Notostraca | Description
The spines are located at the tip. Tripods and tetrapods are very abundant. The tripods are true tripods. Tetrapods are similar to tripods in that they also possess stout actines and a raised centre. However, they have developed a fourth, apical, actine, which is shorter than the facial ones; it is conical and differs from the apical actine of the tetractines in that it is smooth.
Borojevia tetrapodifera | Description
The structure of the tibia in most other tetrapods is essentially similar to that in humans. The tuberosity of the tibia, a crest to which the patellar ligament attaches in mammals, is instead the point for the tendon of the quadriceps muscle in reptiles, birds, and amphibians, which have no patella.
Tibia | Other animals
In some of the eyeless genera ("Ductina") the suture coincides with the marginal suture, and thus appears to be absent. The part of the skeleton that is "tucked under" (the doublure) has no sutures crossing it to form a rostral plate. The thorax has 11 (rarely 10) segments, the side lobes (or pleurae) are furrowed, and the articulating facets distinct. The tailshield (or pygidium) is always smaller than the headshield (or cephalon), a situation called micropygous. In the Phacopidae a merger of the anterior and the two pairs of neighbouring lobes of the glabella forms a frontal lobe that expands forward and can be inflated and overhanging the frontal border.
Phacopidae | Description
"Taklamakania", "Pseudampyxina" and "Nanshanaspis" (Raphiophoridae) have 3 thorax segments, but with subtriangular cephalon and pygidium, genal spines, and "Taklamakania" with a frontal glabellar spine.
Eodiscina | Differences with some other simplified trilobites
The body consists of a head and thorax, separated by a slight constriction. Unlike many other crustaceans, the body is not clearly divided into segments. The abdomen is regressed or absent, whereas the adult gonads are relatively large. The head is the largest part of the body, and bears most of the appendages. Two pairs of well-developed antennae are used to swim through the water. In addition, there is a pair of mandibles and two pairs of maxillae. The thorax typically has two pairs of appendages, but these are reduced to a single pair, or entirely absent, in many species.
Ostracod | Body parts
In almost all modern arthropods, the trunk is further divided into a "thorax" and an "abdomen", with the thorax bearing the main locomotory appendages. In some groups, such as arachnids, the cephalon (head) and thorax are hardly distinct externally and form a single tagma, the "cephalothorax" or "prosoma". Mites appear to have a single tagma with no obvious external signs of either segments or separate tagmata. Tagmosis proceeded differently in different groups of arthropods, so that the tagmata are not derived from corresponding (homologous) segments, even though the same names may be used for the tagmata. Copepods (a kind of crustacean) provide an example.
Tagma (biology) | Tagmosis
The subphylum Hexapoda (from the Greek for "six legs") constitutes the largest number of species of arthropods and includes the insects as well as three much smaller groups of wingless arthropods: Collembola, Protura, and Diplura (all of these were once considered insects). The Collembola (or springtails) are very abundant in terrestrial environments. "Hexapods" are named for their most distinctive feature: a consolidated thorax with three pairs of legs (six legs). Most other arthropods have more than three pairs of legs.
Hexapoda | Introduction
The basic copepod body consists of a head, a thorax with six segments, ancestrally each with a swimming leg, and an abdomen with five appendageless segments. Except in parasitic species, the body is divided functionally into two tagmata, that may be called a "prosome" and a "urosome", with an articulation between them allowing the body to flex. Different groups of copepods have the articulation at different places. In the Calanoida, the articulation is between the thoracic and abdominal segments, so that the boundary between the prosome and urosome corresponds to the boundary between thoracic and abdominal segments. However, in the Harpacticoida, the articulation is between the fifth and sixth thoracic segments, so that the sixth thoracic segment is in the urosome (see the diagram).
Tagma (biology) | Tagmosis
The vertebra was described by Molnar (1981), and was considered an indeterminate theropod by Agnolin "et al." (2010).
Tahora Formation | Vertebrates
Neighbouring pleurae are displaced because of the large pleurae of the 3rd segment. The back thorax (or opistothorax) consists of about 10 progressively smaller segments with insignificant pleurae. Tail shield (or pygidium) not known.
Biceratops | Description
This further segmentation is usually best seen on the abdomen.
Beetle | Thorax
The trochanter articulates with the coxa but usually is attached rigidly to the femur. In some insects its appearance may be confusing; for example it has two subsegments in the Odonata. In parasitic Hymenoptera the base of the femur has the appearance of a second trochanter.
Arthropod leg | Trochanter
This notably contrasts with those of "Asaphestera", which had massive arrow-shaped ventral plates. As typical for many tetrapods, "Boii" also possessed an interclavicle which was positioned behind the clavicles at the center of the chest. However, the only remnant of this bone in the specimen is a large yet indistinct impression. A single arm bone was also present on the specimen, although paleontologists disagree whether it was a humerus (according to Frič, 1883) or a radius or ulna (according to Carroll, 1966). "Boii" possessed large scales, as preserved in the only known specimen. The scales of the back of the animal were tile-like with rounded corners.
Boii (genus) | Other bones
"S. bullata" have black legs, translucent wings, and do not have a costal spine.
Sarcophaga bullata | Thorax
The thorax consists of 11-17 segments, with the 11th from the front bearing a backward directed spine on the midline.
Redlichia | Description
Some key events in the evolution of the arthropod body resulted from changes in certain Hox genes' DNA sequences. The trunks of arthropods comprise repeated segments, which are typically associated with various structures such as a pair of appendages, apodemes for muscle attachment, ganglia and (at least embryologically) coelomic cavities. While many arthropod segments are modified to a greater or lesser extent (for example, only three of the insect thorax and abdominal segments typically bear appendages), arthropodists widely assume that all of the segments were nearly identical in the ancestral state. However, while one can usually readily see the segmental organisation of the trunks of adult arthropods, that of the head is much less obvious.
Arthropod head problem | Background
In many groups of early tetrapods, each vertebra is formed by three parts: an intercentrum at the front, a pleurocentrum at the back, and a plate-like neural spine jutting out from the top of the vertebrae which may be positioned between the two or fused to the pleurocentrum. In nectrideans, only the pleurocentra are present, and the neural spines are completely fused to them. Their vertebrae also possess an extra set of joints connecting the vertebrae (apophyses), just above the typical set (zygapophyses). Furthermore, their caudal (tail) vertebrae also possess haemal spines which jut out from the bottom of each vertebrae.
Nectridea | Vertebrae
The thorax is broadened in females and elongate in males. The legs are long and slender and bear numerous small serrations; the femora may have four dark brown bands in females. The head is smooth and much longer than it is wide. The eyes are small. The antennae are brown and have 23 segments. The egg capsule is long.
Phasmotaenia lanyuhensis | Description
The typical thoracic leg of an adult insect is adapted for running, rather than for digging, leaping, swimming, predation or the like. The legs of most cockroaches are good examples. However, there are many specialized adaptations, including:
Arthropod leg | Variations in functional anatomy of insect legs
The thorax of "H. suis" is primarily for movement. The three pairs of legs are attached at the thorax. Each leg has large claws for grasping the hair of the host.
Haematopinus suis | Thorax
The thorax is the human chest, or division of an animal's body that lies between the head and the abdomen. Thorax may also refer to:
Thorax (disambiguation) | Introduction
In 1999, thoracic plates were reported to be present in the holotype of "Karenites". Thoracic plates are plates of bone on the underside of the rib cage that are typically found in reptiles, and unusual for mammal relatives like therocephalians. This bone was later reinterpreted as an interclavicle, part of the pectoral girdle common to all early therapsids.
Karenites | Description
They are made up of thousands of little receptors called ommatidia. The antennae are covered with many chemical receptors and act as sensory organs. "N. tomentosus" has a mandible for chewing its food. The thorax is the center of movement. It is separated into three different regions: the prothorax, the mesothorax, and the metathorax. It is heavily scleratized which provides extra support and acts as an anchor for moving parts. It is also divided into three different sections. The notum is the top most or dorsal area, the sternum is the lower or ventral side, and the pleuron is the sides where the legs are attached.
Nicrophorus tomentosus | Anatomy
With the move from water to land, the spine had to resist the bending caused by body weight and had to provide mobility where needed. Previously, it could bend along its entire length. Likewise, the paired appendages had not been formerly connected to the spine, but the slowly strengthening limbs now transmitted their support to the axis of the body.
Tetrapod | Axial skeleton
The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms "prosoma" and "opisthosoma" are equivalent to "cephalothorax" and "abdomen" in some groups.) The word "cephalothorax" is derived from the Greek words for head (, ') and thorax (, '). This fusion of the head and thorax is seen in chelicerates and crustaceans; in other groups, such as the Hexapoda (including insects), the head remains free of the thorax. In horseshoe crabs and many crustaceans, a hard shell called the carapace covers the cephalothorax.
Cephalothorax | Introduction
Palpi with second joint reaching above vertex of head. Third joint with a tuft of hair on the inner side. Antennae of male with long bristles and cilia. Thorax and abdomen smoothly scaled. Tibia naked. Forewings with veins 8 and 9 anastomosing (fusing) to form a short areole. Hindwings with vein 5 from middle of discocellulars. Cilia of both wings are crenulate (scalloped).
Tadaxa | Description