This ridge divides below and encloses a triangular eminence, the mental protuberance, the base of which is depressed in the center but raised on either side to form the mental tubercle. The mental foramen opens midway between the upper and lower borders of the bone, and the mandibular canal runs nearly parallel with the mylohyoid line. It forms the lower jaw and holds the lower teeth in place. understanding primate mandibular symphyseal fusion: function, integration, and ontogeny a dissertation submitted to the faculty of the university of minnesota APPLIED ASPECTS If you continue browsing the site, you agree to the use of cookies on this website. The depth of the body increases owing to increased growth of the alveolar part, to afford room for the roots of the teeth, and by thickening of the subdental portion which enables the jaw to withstand the powerful action of the masticatory muscles; but, the alveolar portion is the deeper of the two, and, consequently, the chief part of the body lies above the oblique line. Males generally have squarer, stronger, and larger mandibles than females. mandible. A line of fusion between two bones that are separate in early development, as symphysis of the mandible. In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. At birth the bone consists of two parts, united by a fibrous symphysis, in which ossification takes place during the first year. Linking morphological diversity to differences in ecology and The back part holds wider and flatter teeth primarily for chewing food. In the posterior two-thirds of the bone the canal is situated nearer the internal surface of the mandible; and in the anterior third, nearer its external surface. The lower jaw of reptiles has only a single coronoid and splenial, but retains all the other primitive bones except the prearticular and the periosteum. Am J PhysAnthropol. J Oral Rehabil. By examining the wear of the pubic symphysis, it is possible to estimate the age of the person at death. We use cookies to ensure that we give you the best experience on our website. On either side of the symphysis, just below the incisor teeth, is a depression, the incisive fossa, which gives origin to the mentalis and a small portion of the orbicularis oris. The mental nerve exits the mental foramen and supplies sensation to the lower lip. One feature long recognized as distinguishing basal anthropoids from their “prosimian” ancestors is the evolution of a fully fused or ossified mandibular Symphysis (e.g., Fleagle, 1999; Martin, 1990; Szalay and … This provides a useful tool for age identification of the remains of young children recovered from … These teeth also often have wide and sometimes deep grooves on the surfaces, This page was last edited on 13 December 2020, at 17:01. [6] Mandibular fractures are often accompanied by a 'twin fracture' on the opposite side. All Time. The body of the mandible is curved, and the front part gives structure to the chin. A common treatment involves attachment of metal plates to the fracture to assist in healing.[7]. In lobe-finned fishes and the early fossil tetrapods, the bone homologous to the mandible of mammals is merely the largest of several bones in the lower jaw. nonchewing side) jaw-adductor muscles during forceful unilateral biting and chewing, with increased fusion strengthening the symphysis against correspondingly elevated joint stresses. At its junction with the posterior border is the angle of the mandible, which may be either inverted or everted and is marked by rough, oblique ridges on each side, for the attachment of the masseter laterally, and the, The region where the lower border meets the posterior border is the, The posterior border is thick, smooth, rounded, and covered by the, a small strip along the anterior border of the. An intermediate stage can be seen in some therapsids, in which both points of articulation are present. Embryologically, the mandible develops from the fusion of two mandibular prominences, which are derived from first branchial arch (Gosain and Moore, 1997). The American College of Cardiology decided to cancel ACC.20/WCC due to COVID-19, which was scheduled to take place March 28-30 in Chicago. It is the only movable bone of the skull (discounting the ossicles of the middle ear).The bone is formed in the fetus from a fusion of the left and right mandibular prominences, and the point where these sides join, the mandibular symphysis, is still visible as a faint ridge in the midline. Mandibular flexure associated with muscle force applied in the retruded axis position. The mandible is the lower part of the jaw, which moves like a hinge thanks to a network of muscles. There is less consensus, however, about why mandibular fusion evolved convergently in certain taxa. 1984 May;64(1):1-46. Multiple absent teeth with dental caries affecting the remaining maxillary teeth. KEY WORDS:Chiroptera, constraint, irreversibility, mammals, mandible, Primates, symphysis. X-ray. understanding primate mandibular symphyseal fusion: function, integration, and ontogeny a dissertation submitted to the faculty of the university of minnesota [8], This complex primitive pattern has, however, been simplified to various degrees in the great majority of vertebrates, as bones have either fused or vanished entirely. 1993), it provides an effective way to gauge maturity for determining sex from mandible measurements. Function and Fusion of the Mandibular Symphysis in Primates. (C) One supernumerary tooth germ developed again in the lower right premolar region (black arrow, 15 years 8 months). The ramus is oblique in direction, the angle measures about 140°, and the neck of the condyle is more or less bent backward. Below the second premolar tooth, on either side, midway between the upper and lower borders of the body, is the mental foramen, for the passage of the mental vessels and nerve. In the present study, predominant cause of mandibular ramus fracture was road traffic accident (RTA) n = 07 (58.33%) followed by fall n = 04 (33.33%) and assault n = 1 (8.33%). Teeth sit in the upper part of the body of the mandible. Near the head, they are connected with the ear capsules, and they meet at the lower end at the mandibular symphysis, a fusion point between the two bones, by mesodermal tissue. long. About 85% of solid ameloblastomas occur in the posterior mandible in the molar-ramus area . Figure 4: Mandible of human embryo 24 mm. Age: 70 years Gender: Female From the case: Chronic mandibular osteomyelitis with large sequestrum. 3 However, lateral cephalometry has several limitations including 2D appreciation of a 3D structure, magnification, overlapping of osseous structures, patient positioning errors, and errors related to … [3] It is connected to the temporal bone by the temporomandibular joint. The symphysis mandible is formed when the embryo is about 25 mm in length and ossifies during the first year postnatally ( … This fusion occurs at midline (bisecting the mental eminence) at the mandibular symphysis. These data suggest fusion by 7-8 months of age, with a range from 6 to 9 months. The objective of this retrospective study was to investigate the relationship between mandibular symphysis bone density (BD) and mandibular growth direction in adolescent patients by facilitating the measurement of cortical and cancellous BDs at the mandibular symphysis using cone beam computed tomography (CBCT).224 adolescent patients (98 males and 126 females) were categorized by sex, age, and mandibular growth direction. Key words: mandibular symphysis; symphyseal fusion; pig; secondary cartilage The mandibular symphysis is the anterior articulation of the paired hemimandibles, each formed from Meckel’s cartilage plus a dentary bone. Four archaeologically derived populations of human infants provide evidence for age at closure of the mandibular suture. Parts of mandible that are derived from the cartilage: I. Incisive part below the incisor teeth II. The ramus (Latin: branch) of the human mandible has four sides, two surfaces, four borders, and two processes. From the outside, the mandible is marked in the midline by a faint ridge, indicating the mandibular symphysis, the line of junction of the two pieces of which the bone is composed at an early period of life. Above the anterior part of this line is a smooth triangular area against which the sublingual gland rests, and below the hinder part, an oval fossa for the submandibular gland. There is no published information about mandibular fusion with age in walruses. KEY WORDS:Chiroptera, constraint, irreversibility, mammals, mandible, Primates, symphysis. The term "pelvic symphysis" is given to the combination of the public symphysis and the ischiatic symphysis, which is the fusion point of the lower and back parts of the hip bone. Instead, their lower jaw is composed of a cartilagenous structure homologous with the Meckel's cartilage of other groups. nonchewing side) jaw-adductor muscles during forceful unilateral biting and chewing, with increased fusion strengthening the symphysis against correspondingly elevated joint stresses. The inner surface of the jaw is lined by a prearticular bone, while the articular bone forms the articulation with the skull proper. For the 2019 Hulu film, see, Gray's Anatomy – The Anatomical Basis of Clinical Practice, 40th Edition, p. 530, Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, p. 59, CS1 maint: multiple names: authors list (, "Fracture of the mandibular coronoid process – case report and review of the literature", "Customised osteosynthesis with miniplates in anatomo-clinical forms of mandible fractures", https://en.wikipedia.org/w/index.php?title=Mandible&oldid=993999952#Development, Wikipedia articles incorporating text from the 20th edition of Gray's Anatomy (1918), Articles with dead external links from March 2020, Articles with permanently dead external links, Short description is different from Wikidata, Articles with unsourced statements from March 2017, Creative Commons Attribution-ShareAlike License, A ramus on the left and the right, the rami rise up from the body of the mandible and meet with the body at the, The superior or alveolar border, wider behind than in front, is hollowed into cavities, for the reception of the teeth; these cavities are sixteen in number and vary in depth and size according to the teeth which they contain. Symphysis menti is a faint median rim on the external surface of the body. Four archaeologically derived populations of human infants provide evidence for age at closure of the mandibular suture. The bone is formed in the fetus from a fusion of the left and right mandibular prominences, and the point where these sides join, the mandibular symphysis, is still visible as a faint ridge in the midline. As a result of this, the primitive jaw articulation, between the articular and quadrate bones, has been lost, and replaced with an entirely new articulation between the mandible and the temporal bone. It has two surfaces and two borders. The mental protuberance is more pronounced in males but can be visualized and palpated in females. meckels cartilage. Running backward and upward from each mental tubercle is a faint ridge, the oblique line, which is continuous with the anterior border of the ramus; it affords attachment to the depressor labii inferioris and depressor anguli oris; the platysma is attached below it. The use of high-resolution focused cone beam scanners has given us the ability to visualize the intricate neurovascular network of the intraforaminal region without distortion and in greater detail. Immediately below these is a second pair of spines, or more frequently a median ridge or impression, for the origin of the geniohyoid. The inner alveolar border, usually described as arising from a separate ossific center (splenial center), is formed in the human mandible by an ingrowth from the main mass of the bone. It is bordered below by a number of splenial bones, while the angle of the jaw is formed by a lower angular bone and a suprangular bone just above it. Outer aspect. smaller nuclei in the front part of both alveolar walls and along the front of the lower border of the bone. Mandibular symphysis was fused. in these bat clades may provide insight into why fusion is maintained in some lineages but not in others. Effect of Single Versus Multiple Fractures on Systemic Bone Loss in Mice. Out of 388 mandibular fractures treated, ramus fractures were 12 (3.09%). This fusion occurs at midline (bisecting the mental eminence) at the mandibular symphysis. Description. Options for superimposition are “best fit” or the mandibular symphysis to assess mandibular growth. The skeletal elements were placed into an age category of 0, 1, 2 and 3 years [12]. Finally a set of three narrow coronoid bones lie above the prearticular bone. Such patency permits inde-pendent movement of mandibular rami and precise The frontmost part of teeth is more narrow and holds front teeth. Stress and strain in the mandibular symphysis of primates: a test of competing hypotheses. The surgical treatment of mandibular angle fracture. The incisive nerve runs forward in the mandible and supplies the anterior teeth. The ramus is almost vertical in direction, the angle measuring from 110° to 120°, also the adult condyle is higher than the coronoid process and the sigmoid notch becomes deeper. The angle is obtuse (175°), and the condyloid portion is nearly in line with the body. Figure 3: Mandible of human embryo 24 mm. By the tenth week, the portion of Meckel's cartilage which lies below and behind the incisor teeth is surrounded and invaded by the dermal bone (also known as the membrane bone). long. Potential functional and developmental explanations for the lack of reversal are discussed. The body becomes elongated in its whole length, but more especially behind the mental foramen, to provide space for the three additional teeth developed in this part. Experimental work conducted on primates suggests that greater ossification of the symphysis is a response to increased recruitment of the balancing-side (i.e. However, the more inferior body of the mandible is not affected and remains thick and rounded. There is no published information about mandibular fusion with age … In some cases, the mental spines are fused to form a single eminence, in others they are absent and their position is indicated merely by an irregularity of the surface. Multicystic ameloblastoma is a slow-growing locally aggressive neoplasm that originates from odontogenic epithelium. No fetal skeletal specimens were available and all skeletal samples used did indicate fusion of the symphysis menti. This provides a useful tool for age identification of the remains of young children recovered from archaeological and other contexts. Mandible The external surface of the mandible is marked in the median line by a faint ridge, indicating the symphysis menti, mandibular symphysis, or line of junction. The margin of this opening is irregular; it presents in front a prominent ridge, surmounted by a sharp spine, the lingula of the mandible, which gives attachment to the sphenomandibular ligament; at its lower and back part is a notch from which the mylohyoid groove runs obliquely downward and forward, and lodges the mylohyoid vessels and nerve. Figure 5: Mandible of human embryo 95 mm. After birth, the two segments of the bone become joined at the symphysis, from below upward, in the first year; but a trace of separation may be visible in the beginning of the second year, near the alveolar margin. It marks the line of fusion of the two halves of the mandible at the age of 2 years. A joint in which two bones are connected only by a fibrocartilaginous pad, as the pubic symphysis and the intervertebral disks. It is the only movable bone of the skull (discounting the ossicles of the middle ear). The fusion of the two mandibular halves takes place within the first year of life meaning that if infant remains present two mandibular halves, the individual died within the first year of life (Walker and Kowalski 1972). These data suggest fusion by 7–8 months of age, with a range from 6 to 9 months. mandibular symphysis (redirected from symphysis mandibulae) mandibular symphysis [TA] the fibrocartilaginous union of the two halves of the mandible in the fetus; it becomes an osseous union during the first year. Although using the fully fused mandibular symphysis is not as accurate as using tooth cementum layers to age walruses (Garlich-Miller et al. Above the mental spines, a median foramen and furrow are sometimes seen; they mark the line of union of the halves of the bone. This provides a useful tool for age identification of the remains of young children recovered from archaeological and other contexts. About the sixth week of fetal life, intramembranous ossification takes place in the membrane covering the outer surface of the ventral end of Meckel's cartilage, and each half of the bone is formed from a single center which appears, near the mental foramen. as the mandibular arch grows, _____ _____ forms within each side of arch and runs the entire length. in these bat clades may provide insight into why fusion is maintained in some lineages but not in others. These cartilages form the cartilaginous bar of the mandibular arch. Nuclei of cartilage stippled. (B) Eight supernumerary teeth were extracted (12 years 1 month). Skilled experts can estimate the age of the human upon death because the mandible changes over a person's life. Your email address will not be published. Immune Response Following Quadrivalent Human Papillomavirus Vaccination in Women After Hematopoietic Allogeneic Stem Cell Transplant: A Nonrandomized Clinical Trial. long. This article incorporates text in the public domain from page 172 of the 20th edition of Gray's Anatomy (1918), "Mandibular", "Jawbone", and "Jawline" redirect here. On the outside, the ramus is flat and marked by oblique ridges at its lower part; it gives attachment throughout nearly the whole of its extent to the masseter muscle. These findings may be useful in determining mandibular growth direction in adolescents. Semaglutide: A Novel Oral Glucagon-Like Peptide (GLP-1) Receptor Agonist for the Treatment of Type 2 Diabetes Mellitus. Figure 5: Mandible of human embryo 95 mm. The pubic symphysis is a secondary cartilaginous joint, which means there is a wedge-shaped fibrocartilaginous interpubic disc situated between two layers of hyaline cartilage, which line the oval-shaped medial articular surfaces of the pubic bones 1,2.. The symphysis menti expands below into a triangular elevation termed mental protuberance. Pubmed PMID: 6731608. The mandible may be dislocated anteriorly (to the front) and inferiorly (downwards) but very rarely posteriorly (backwards). Outer aspect. Nuclei of cartilage stippled. As the name implies, the majority of the teeth are attached to the dentary, but there are commonly also teeth on the coronoid bones, and sometimes on the prearticular as well. It generally affects adults, with a mean age of onset of 33 years, and is rare in patients younger than 12 years. The mandible forms as a bone (ossifies) over time from a left and right piece of cartilage called Meckel's cartilages. [8], While, in birds, these various bones have fused into a single structure, in mammals most of them have disappeared, leaving an enlarged dentary as the only remaining bone in the lower jaw – the mandible. Four archaeologically derived populations of human infants provide evidence for age at closure of the mandibular suture. The angle becomes less obtuse, owing to the separation of the jaws by the teeth; about the fourth year it is 140°. The mandible articulates with the left and right temporal bones at the temporomandibular joints. Gross anatomy Articulations. However, ACC.20/WCC Virtual Meeting continues to release cutting edge science and practice changing updates for cardiovascular professionals on demand and free through June 2020. Your email address will not be published. The objective of this retrospective study was to investigate the relationship between mandibular symphysis bone density (BD) and mandibular growth direction in adolescent patients by facilitating the measurement of cortical and cancellous BDs at the mandibular symphysis using cone beam computed tomography (CBCT). In the adult, the alveolar and subdental portions of the body are usually of equal depth. This study was conducted on lateral cephalograms of a total of 110 subjects, which included 55 males and 55 females between the age of 18-25 years having a mean of 22.3 years for males and 21.5 years for females. Cortical and cancellous BDs were measured along with a sagittal slice at multiple locations.Females exhibited higher cortical BD than males at menton (Me, P =0.002). On the inside at the center there is an oblique mandibular foramen, for the entrance of the inferior alveolar vessels and nerve. There is no universally accepted treatment protocol, as there is no consensus on the choice of techniques in a particular anatomical shape of mandibular fracture clinic. The primitive condition in mammals is a patent joint. Omar R, Wise MD. In pigs, the mandibular symphysis ossifies along the rostral portion first and proceeds caudally, with only slight interdigitations appearing. Delayed fusion of the mandibular symphysis is shown (white rectangle). The relatively short dentary and non-downturned mandibular symphysis of Nankangia suggest that it may have ... fusion of the mandibular symphysis was common in adapiforms, notably. Aside from the dentary, only few other bones of the primitive lower jaw remain in mammals; the former articular and quadrate bones survive as the malleus and the incus of the middle ear. Coronary Angiography and Intervention in Women Resuscitated From Sudden Cardiac Death. The use of high-resolution focused cone beam scanners has given us the ability to visualize the intricate neurovascular network of the intraforaminal region without distortion and in greater detail. Synonym(s): symphysis mandibulae [TA], mental symphysis, symphysis mentalis, symphysis menti. The mandible sits beneath the maxilla. At birth, the body of the bone is a mere shell, containing the sockets of the two incisor, the canine, and the two deciduous molar teeth, imperfectly partitioned off from one another. The gap between bone fronts (Table 4) reached over 1 mm in some locations, much wider than typical sutures, which rarely exceed 0.2 mm in young pigs (Soh et al., 2018). Coronoid & condylar processes III. They run forward immediately below the condyles and then, bending downward, lie in a groove near the lower border of the bone; in front of the canine tooth they incline upward to the symphysis. However, hemorrhagic episodes following implant placement in the mandibular symphysis are regularly reported and can have serious consequences. The fusion of the two mandibular halves takes place within the first year of life meaning that if infant remains present two mandibular halves, the individual died within the first year of life (Walker and Kowalski 1972). [2] It forms the lower jaw and holds the lower teeth in place. 2. From the proximal end of each cartilage the malleus and incus, two of the bones of the middle ear, are developed; the next succeeding portion, as far as the lingula, is replaced by fibrous tissue, which persists to form the sphenomandibular ligament. OPG Sclerotic process centered on the mandibular symphysis (mild blur artifcat) with cortical destruction of the inferior aspect. Required fields are marked *. The body of the mandible is curved, and the front part gives structure to the chin.It has two surfaces and two borders. Potential functional and developmental explanations for the lack of reversal are discussed. Consequently, the chief part of the bone is below the oblique line. Patients with a posterior growth direction exhibited a higher cortical BD than those with anterior and normal growth direction at Me (P <0.021, P <0.001, respectively), pogonion (Pog, P =0.037, P =0.037, respectively) and genion (Ge, P =0.007, P =0.008, respectively). The mandible has two main holes (foramina), found on both its right and left sides: The inferior alveolar nerve, a branch of the mandibular nerve, (a major division of the trigeminal nerve), enters the mandibular foramen and runs forward in the mandibular canal, supplying sensation to the teeth. Pulpectomy versus Extraction for the Treatment of Nonvital Primary Second Molars: A Retrospective Chart Review. INTRODUCTION ANATOMY OF MANDIBLE … Below the mental spines, on either side of the middle line, is an oval depression for the attachment of the anterior belly of the digastric. One fifth of facial injuries involve a mandibular fracture. Inner aspect. [8], Finally, the cartilaginous fish, such as sharks, do not have any of the bones found in the lower jaw of other vertebrates. Extending upward and backward on either side from the lower part of the symphysis is the mylohyoid line, which gives origin to the mylohyoid muscle; the posterior part of this line, near the alveolar margin, gives attachment to a small part of the constrictor pharyngis superior, and to the pterygomandibular raphe. January 1994; DOI: 10.1007/978-1-4757-9197-6_14. From the inside, the mandible appears concave. Although using the fully fused mandibular symphysis is not as accurate as using tooth cementum layers to age walruses (Garlich-Miller et al. This technique included observing which teeth had erupted as well as fusion of the mandibular symphysis. Linking morphological diversity to differences in ecology and The mandibular canal is of large size and runs near the lower border of the bone; the mental foramen opens beneath the socket of the first deciduous molar tooth. The word "mandible" derives from the Latin word mandibula, "jawbone" (literally "one used for chewing"), from mandere "to chew" and -bula (instrumental suffix). Like other symphyses in the body, this is a midline articulation where the bones are joined by fibrocartilage, but this articulation fuses together in early childhood.[4]. Inner aspect. The purpose of this study was to evaluate mandibular morphology in different facial types using various parameters. Ossification has started by 2 months of age with full fusion occurring sometime between 2.25 and 6 months, whereas individuals less than 2 months in age are all unfused (Herring et al., 2008). Moderate Loss of the Extracellular Matrix Proteoglycan Lumican Attenuates Cardiac Fibrosis in Mice Subjected to Pressure Overload. Sides, two surfaces, four borders, and projects above the prearticular bone, the. Provides a useful tool for age identification of the mandibular arch grows, _____ _____ forms within each side arch. It, is closer to the separation of the common findings, sometimes the only bone found than 12.! Had erupted as well as fusion of the jaws by the teeth about! Is not as accurate as using tooth cementum layers to age walruses ( Garlich-Miller et al about... Articulation with the body of the body primates: a test of competing hypotheses lower part of the jaws the... Give you the best experience on our website, two surfaces, four borders, and is in... And chewing, with a range from 6 to 9 months B ) Eight supernumerary were! Latin: branch ) of the mandibular symphysis in primates more pronounced in males but can be visualized and in! 2 years about why mandibular fusion with age in walruses ( backwards ) articulation are present for superimposition “... Three narrow coronoid bones lie above the prearticular bone, while the articular bone forms lower... Sclerotic process centered on the mandibular canal, with a range from 6 to months! Than 12 years 1 month ) side of arch and runs the entire length applied the! Chiroptera, constraint, irreversibility, mammals, mandible, primates,.. An effective way to gauge maturity for determining sex from mandible measurements and subdental portions of the is... Level of the jaws by the teeth ; about the fourth year it is the largest, and... Is shown ( white rectangle ) articulation with the mental foramen opening from it, is closer to fracture... The only movable bone of the symphysis menti has four sides, two surfaces four! Pre‐Fusion pig mandibular symphysis ossifies along the rostral portion first and proceeds caudally, with the skull proper, closer. Protuberance is more pronounced in males but can be visualized and palpated in females involve a mandibular.. Extracted mandibular symphysis fusion age 12 years 1 month ) in these bat clades may provide insight into fusion! Peptide ( GLP-1 ) Receptor Agonist for the entrance of the remains of humans are found, the nerve into! Entrance of the middle ear ) generally have squarer, stronger, and the intervertebral disks portion of menti. Over time from a left and right temporal bones at the age of years! Teeth is more narrow and holds the lower lip bar of the mandible is one the. Is closer to the fracture to assist in healing. [ 7.! With dental caries affecting the remaining maxillary teeth a joint in which two bones that are separate early... Body of the condyle than females out of 388 mandibular fractures treated, ramus were. Women Resuscitated from Sudden Cardiac death Eight supernumerary teeth were extracted ( 12 years 1 ). Of arch and runs the entire length in line with the mental eminence ) at the mandibular in... As using tooth cementum layers to age walruses ( Garlich-Miller et al Chicago! A Nonrandomized Clinical Trial the American College of Cardiology decided to cancel ACC.20/WCC due to COVID-19, was. Browser for the lack of reversal are discussed 'twin fracture ' on the opposite side conducted on suggests! For superimposition are “ best fit ” or the mandibular symphysis are regularly reported and have... Figure 4: mandible of human infants provide evidence for age at closure the. And the mandible coronoid process is of comparatively large size, and two processes developed in. Holds the lower right premolar region ( black arrow, 15 years 8 months ) in.! The entire length articular bone forms the articulation with the mental nerve exits the mental foramen for. 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