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see ribrib,
one of the slender, elongated, curved bones that compose the chest cage in higher vertebrates. Ribs occur in pairs, and are found in most vertebrates; however, in some lower vertebrates, including fishes, they run along the entire length of the backbone.
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the complex of skeletal elements in terrestrial vertebrates and man that unite, along the midline of the body, the ventral ends of the true ribs and parts of the pectoral girdle and to which the sternal muscles are attached.

The sternum is a derivative of the ribs and first appeared in terrestrial vertebrates when a strengthening of support for the pectoral girdle was required in connection with the progressive evolution of the forelimbs. In amphibians and reptiles the sternum is usually cartilaginous; in the latter, only a few ribs are attached, forming the thorax. In birds the sternum is osseous; in flying birds there is a median process, the keel, to which the powerful pectoral muscles are attached. In mammals the sternum consists of three sections: the manubrium, the corpus sterni, and the xiphoid process. In man the sternum, or breastbone, is an unpaired flat bone that forms the middle part of the anterior wall of the thorax.


The bone, cartilage, or series of bony or cartilaginous segments in the median line of the anteroventral part of the body of vertebrates above fishes, connecting with the ribs or pectoral girdle.


1. (in man) a long flat vertical bone, situated in front of the thorax, to which are attached the collarbone and the first seven pairs of ribs
2. the corresponding part in many other vertebrates
3. a cuticular plate covering the ventral surface of a body segment of an arthropod
References in periodicals archive ?
sterna muestra reclutamientos en colectores artificiales durante todo el ano, coincidiendo con la estrategia de reproduccion continua, por lo que Marquez et al.
sterna realizo desoves parciales practicamente todo el ano, lo que fue confirmado por Monteforte (2005), quien registro la actividad reproductiva continua de esta especie en Bahia de La Paz, Mexico, observando dos ciclos de desove y reclutamiento en colectores durante verano e invierno, aspecto que se observaria en las especies perleras netamente tropicales como Pinctada albina (Lamarck, 1819), P.
sterna de los bancos silvestres durante el periodo de 1997-99 (n=233 ostras) siendo recolectadas al azar mediante buceo con Hooka o compresor en las inmediaciones del estero San Luciano.
sterna comprendidos en la franja costera del estero de Mulege y de la bahia de Loreto.
In general, the sex ratio of the Pteria sterna population living in the Ojo de Liebre lagoon was found at 1:1 (P > 0.
sterna is one of the smallest species of the Pteriidae family, organisms of this species are believed to ripen at small sizes (Saucedo & Monteforte 1997).
A half-brother to Derby winner Dr Devious, Archway was standing at Castle Hyde Stud for Ir1,250gns in 1996, when Sterna Star visited him.
The product of Sterna Star's initial visit to Archway was a foal that both Patrick and Louise felt was destined for big things.
sterna II and III (2+2 and 2+2) and are characterized by lacking the pso on all subcoxae 1's, but can be easily distinguished by different pso formulas (32/01(2)2/331(2)32 dorsally and 2/000/0000 ventrally in the new species, 32/022/33332 dorsally and 2/000/0001 ventrally in P.
sterna I, II and on upper anal valve (psx formula 0/000/110001m) (Fig.
Moreover, the total numbers of seabirds were due to two species: Sterna hirundo, which accounted for 40% of all seabirds (of which 81% were tallied in a single period), and Phalacrocorax brasilianus, with 33% of the individuals.
sterna I-IV: 2212, PAO with 14-16 vesicles, mvo present .