Tho"rax (?), n. [L., fr. Gr. &?;.]
1. (Anat.) The part of the trunk between the
neck and the abdomen, containing that part of the body cavity the walls of
which are supported by the dorsal vertebræ, the ribs, and the
sternum, and which the heart and lungs are situated; the chest.
&fist; In mammals the thoracic cavity is completely separated from the
abdominal by the diaphragm, but in birds and many reptiles the separation
is incomplete, while in other reptiles, and in amphibians and fishes, there
is no marked separation and no true thorax.
2. (Zoöl.) (a) The
middle region of the body of an insect, or that region which bears the legs
and wings. It is composed of three united somites, each of which is
composed of several distinct parts. See Illust. in Appendix. and
Illust. of Coleoptera. (b) The
second, or middle, region of the body of a crustacean, arachnid, or other
articulate animal. In the case of decapod Crustacea, some writers include
under the term thorax only the three segments bearing the
maxillipeds; others include also the five segments bearing the legs. See
Illust. in Appendix.
3. (Antiq.) A breastplate, cuirass, or
corselet; especially, the breastplate worn by the ancient Greeks.
Tho"rax (?), n. [L., fr. Gr. &?;.]
1. (Anat.) The part of the trunk between the
neck and the abdomen, containing that part of the body cavity the walls of
which are supported by the dorsal vertebræ, the ribs, and the
sternum, and which the heart and lungs are situated; the chest.
&fist; In mammals the thoracic cavity is completely separated from the
abdominal by the diaphragm, but in birds and many reptiles the separation
is incomplete, while in other reptiles, and in amphibians and fishes, there
is no marked separation and no true thorax.
2. (Zoöl.) (a) The
middle region of the body of an insect, or that region which bears the legs
and wings. It is composed of three united somites, each of which is
composed of several distinct parts. See Illust. in Appendix. and
Illust. of Coleoptera. (b) The
second, or middle, region of the body of a crustacean, arachnid, or other
articulate animal. In the case of decapod Crustacea, some writers include
under the term thorax only the three segments bearing the
maxillipeds; others include also the five segments bearing the legs. See
Illust. in Appendix.
3. (Antiq.) A breastplate, cuirass, or
corselet; especially, the breastplate worn by the ancient Greeks.
