File:Bailey130.jpg

Fig. 130. Ventral view of developing sternum of human embryo of 30 mm

(beginning of 3rd month).

Ruge, Kollmann's Atlas.

The sternum, according to Hanson's recent contribution, originates independently of the ribs. On each side, some distance from the midventral line, the sternal band or bar arises as a mesenchymal condensation in the body wall. These bars then approach the midventral line and fuse with each other to form a single cartilaginous structure. Meanwhile the ventral ends of the first seven ribs extend far enough to come into contact with and join the sternal bar (Fig. 130). Before the two bars have united a medial unpaired rudiment appears opposite their anterior ends to form the presternum with which the paired rudiments subsequently unite. The presternal component, with which the clavicles articulate, probably represents the ventral part of the primitive vertebrate shoulder girdle.

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Reference

Bailey FR. and Miller AM. Text-Book of Embryology (1921) New York: William Wood and Co.

Cite this page: Hill, M.A. (2024, April 27) Embryology Bailey130.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Bailey130.jpg

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