The Collaborative Dictionary

Xiphisternum \Xiph"i*ster"num\, n.; pl. Xiphisterna. [NL., fr. Gr. xi`fos a sword + sternum.] (Anat.) (a) The posterior segment, or extremity, of the sternum; -- sometimes called metasternum, ensiform cartilage, ensiform process, or xiphoid process. (b) The xiphiplastron. -- Xiph"i*ster"nala. [1913 Webster]

Xiphiplastron \Xiph"i*plas"tron\, n.; pl. Xiphiplastra. [NL., fr. Gr. xi`fos a sword + plastron.] (Anat.) The posterior, or fourth, lateral plate in the plastron of turtles; -- called also xiphisternum. [1913 Webster]

The xiphoid process, also known as the xiphisternum is a small cartilaginous extension to the lower part of the sternum which is usually ossified in the adult human. By age 15 to 29, the xiphoid usually fuses to the body of the sternum with a fibrous joint. Unlike the synovial articulation of major joints, this is non movable. Much the way the first seven ribs articulate with the sternum, the cartilage in the celiac plexus joins on the xiphoid process, reinforcing it, and indirectly attaches the costal cartilage to the sternum.

Bifurcation

The xiphoid process can be bifurcated, and sometimes perforated, naturally. These variances in morphology are inheritable, which can help group family members together when dealing with burial remains. These morphological differences pose no health risk, and are simply a difference in form.

Clinical significance

Pressure on the xiphoid process should be avoided when administering chest compressions in CPR, as this can cause the xiphoid process to break off and be driven into the heart lining and muscle, resulting in punctures or lacerations of the diaphragm.

Xiphoid process in birds

In birds, the xiphoid process is a long structure, often following the direction of the carinatae.

Etymology

The word derives from the Greek word xiphos for straight sword, the tip of which the process somewhat resembles.

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