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body division found in certain animals. In humans and other mammals it lies between the neck and abdomen and is also called the chest. The skeletal frame of the thorax is formed by the sternum (breastbone) and ribs in front and the dorsal vertebrae in back. Within the thoracic cavity are the heart, lungs, and esophagus. The chest and abdominal cavities are separated by a muscular structure, the diaphragm. In insects and other arthropods the thorax is a body division consisting of several segments lying between the head and abdomen, to which are attached legs or other appendages.



the upper (in humans) or anterior (in most vertebrates) part of the trunk.

The shape of the thorax is determined by its skeleton—the chest and pectoral girdle—and by the muscles arranged on its surface. In arthropods the thorax is the section between the head and the abdomen. In primitive crustaceans (for example, Phyllopoda) the segments of the thorax are numerous and not constant in number; they bear nonspecialized appendages, equipped simultaneously for swimming, chewing, and breathing (gills). In higher crustaceans the number of segments of the thorax is reduced to between four and eight and becomes constant; part of the segments fuse with the head and their appendages become maxillipedary. In Arachnida and Xiphosura the segments of the thorax bear four pairs of gressorial legs and are usually merged with the head into a cephalothorax. In insects the thorax consists of three segments (prothorax, mesothorax, and metathorax), to each of which is attached a pair of legs; in higher insects one pair of wings each is attached to the mesothorax and metathorax in the adult stage.


The chest; the cavity of the mammalian body between the neck and the diaphragm, containing the heart, lungs, and mediastinal structures. Also known as thoracic cavity.
(invertebrate zoology)
The middle of three principal divisions of the body of certain classes of arthropods.


1. the part of the human body enclosed by the ribs
2. the corresponding part in other vertebrates
3. the part of an insect's body between the head and abdomen, which bears the wings and legs
References in periodicals archive ?
As far as the thorax width is concerned, it was minimum 0.
5: Showing frequency of Injuries in different parts of the Thorax and Management offered.
Indeed, this is reflected in the response of the 2 trainees who thought that the sheep chest model did not resemble the human thorax.
Some parts of liver, stomach, spleen and intestines were also visible in the thorax.
Radiographic findings in cases of hypoplasia are similar and characterized principally by almost total absence of aerated lung in one hemi thorax.
Grey or brown flies with at least 3 dark longitudinal stripes on thorax.
These patients will often exhibit subcutaneous emphysema in the neck and upper thorax.
Thorax black with gray pollen except postalar callus, pteropleuron mostly and postero-upper corner of mesopleuron brownish yellow.
This pocket atlas presents sectional anatomy of the thorax, heart, abdomen, and pelvis, with computed tomography (CT) and magnetic resonance (MR) images on one page and color diagrams on the other.
This suggests that these cues are mainly located in the head, even though additional signals can be also found on the thorax, because the recognition is lost in treatments where only the gaster was tested.
The bumblebee has a brown thorax, a dark abdomen and a white tip
Stuart Physical Therapy in Leavenworth completed "Visceral Manipulation 4-The Thorax," a continuing education course taught through the Barral Institute in Seattle in November.