the breastbone is commonly cut open (a sternotomy) to benefit access to the pectoral contents while performing cardiothoracic surgery.

Overview
A breastbone (Figs. 1 to 3) is an longer, planate bone, forming a middle part of the prior wall of the thorax. Its upper prevent supports a clavicles (Collar bones), and its margins articulate by owning a gristle of the 1st seven pairs of ribs. It consists of iii area, known as from either above down, a manubrium, a system or even gladiolus, & a xiphoid process; in early life a immune system consists of quadruplet segments or even sternebrœ. Inside its natural position a inclination of the bone is oblique from either above, downwards & send on. These are slightly bulging before & concave behind; broad above, becoming narrowed at a point in which a manubrium joins a person, when which it once again widens a little to in the image below the middle of the system, then narrows to its moo extremity. Its typical length in the adult is astir Seventeen cm, and is like hanker in the male than in the female.

Manubrium
("manubrium sterni") A manubrium is the wide, upper section of the breastbone. By having a quadrangular shape, wider superiorly & narrower inferiorly, it articulates by owning the clavicles and a 1st 2 ribs.

Surfaces
Its prior surface, bulging in diameter, concave from either above downwards, is smooth, & affords attachment in either side to the sternal origins of the Pectoralis major & Sternocleidomastoideus. Periodically a ridges limiting a attachments one muscles may be distinct. Its tail surface, concave & smooth, affords attachment in either side to the Sternohyoideus & Sternothyreoideus.

image:Gray116.png Figure Two : Tail surface of breastbone.

image:Gray117.png Figure Three : Lateral border of breastbone.

Borders
A superior even border is a thickest & presents at its center a jugular or presternal notch; in either side of the notch is an oval-shaped articulary surface, directed upward, feebleminded, & lateralward, for articulation sustaining the sternal prevent of the collarbone. a inferior border, ellipse & rough, is covered around the newly state by using a thinly layer of gristle, for articulation by owning the immune system. the lateral borders come apiece marked above by the depression for the 1st costal cartilage, & in the image below by the little facet, which, sustaining the similar facet on the upper angle of the person, forms a notch for the reception of the costal cartilage of the 2nd rib. Between a depression for a number 1 costal cartilage & the demi-facet for the 2nd occurs as narrow, curving edge, which slopes from either above down & medialward.

Body
("corpus sterni; gladiolus") A immune system, substantially hanker, narrower, & thinly than a manubrium, attains its greatest breadth approximately a moo prevent.

Surfaces
Its prior surface is about flat, directed upward & send on, & marked by trey thwartwise ridges which cross a bone opposite a third, for, & fifth articulary depressions. Xviii It affords attachment in either side to the sternal origin of the Pectoralis major. At a junction of a third & quaternary pieces of the person is now & then seen an opening, the sternal hiatus, of variable size and form. A tail surface, slightly concave, is besides marked by deuce-ace transversal lines, less distinct, still, than people before; from either its lower berth sectiin, on either side, a Transversus thoracis will require origin.

Borders
A superior border is ellipse & articulates sustaining a manubrium, a junction of a 2 forming the sternal angle (angulus Ludovici 19). A inferior border is narrow, & articulates by having a xiphoid run. To each one lateral border [Fig. Trine], at its superior angle, has the little facet, which by having the similar facet on the manubrium, forms the cavity for the gristle of the 2nd rib; in the image below this come quaternity angular depressions which receive the gristle of the third, for, fifth, & sixth ribs, when the inferior angle has the little facet, which, by using a corresponding a single on the xiphoid run, forms a notch for the gristle of the seventh rib. These articulary depressions come separated by the series of curving interarticular intervals, which diminish inside length from either above downwardly, & correspond to the intercostal spaces. Virtually all of a gristle belonging to a true ribs, every bit is seen from either a foregoing description, articulate sustaining the breastbone at the lines of junction of its primitive component segments. This is swell seen inside numbers of of a moo brute, within which the area of the bone remain ununited yearn than in human.

Xiphoid Process
("processus xiphoideus; ensiform or xiphoid appendix") A xiphoid run is the smallest of the threesome pieces: these are thinly & longer, scomberesox saurus around structure within youth, however about ossified at its upper a portion in the adult.

A xiphoid run is an significant landmark. Its articulation sustaining a breastbone at a xiphisternal joint gives an approximation of the inferior border of the chest cavity's projection onto a prior immune system wall. A xiphoid run is at a approximate level of a upper border of the liver & the inferior border of the heart in the midplane of the immune system.

Surfaces
Its prior surface affords attachment in either side to the prior costoxiphoid ligament & the little a portion of the Rectus abdominis; its tail surface, to the tail costoxiphoid ligament & to occasionally of the fibers of the diaphragm & Transversus thoracis, its lateral borders, to the aponeuroses of the ab. Above, it articulates using the moo prevent of the system, & on the front of every superior angle presents a facet for a share of the gristle of the seventh rib; in the image below, by its pointed extremity, it gives attachment to the linea alba. A xiphoid run varies lot inside form; it can be broad & thinly, pointed, bifid, perforated, curving, or even even deflected well to 1 or more side.

Structure
a breastbone is composed of extremely vascular cancellate tissue, covered by a thinly layer of compact bone which is thickest in the manubrium between the articulary facets for the collarbone.

Ossification
A breastba single originally consists of 2 billfish blocks, placed one in either side of a median plane & attached by owning the gristle of the upper nine ribs of its have side. These 2 parallel bars fuse by owning every more along a middle line to form a billfish breastbone which is ossified from either hexad centers: 1 for the manubrium, 4 for the immune system, & 1 for the xiphoid process [Fig. Iv]. A ossific centers pop up inside a intervals between a articulary depressions for a costal cartilages, in a as a result choose: in a manubrium & foremost piece of the system, in the period of the sixth season; in the 2nd & third pieces of the immune system, when you took the seventh year of foetal life; in its 4th piece, in the period of the number one year fallowing birth; & in the xiphoid run, between the fifth & eighteenth years. A centers make their appearance at a upper area of the segments, & proceed bit by bit downwards. Twenty To these can be added a occasional being of ii little episternal centers, which make their appearance a single in either side of the jugular notch; it is probably tincture of the episternal bone of the monotremata & lizards. Now & again a few of a segments come formed from either other than a single center, the total and position of which vary [Fig. Vi]. So, a foremost piece might own ii, deuce-ace, or 6 centers. Once 2 are present, it is usually situated 1 above a additional, a upper existence a larger; a 2nd piece has rarely more than of these; a third, for, & fifth pieces come typically formed from either 2 centers placed laterally, a irregular union of which explains a uncommon occurrence of the sternal foramen [Fig. Septenary], or even of a vertical fissure which on occasion intersects this a share of the bone constituting the malformation called fissura sterni; these conditions come farther explained per manner where a rubbery breastbone is formed. Extrthe seldom however a upper prevent of the breastbone can be divided by a fissure. Union of the various centers of the system begins just about pubescence, & payoff from either following upward [Fig. Pentad]; per age of twenty-25 it is everthing united. A xiphoid run could turn into joined to a person prior to the age of 30, however this occurs extra often when 40; then agaaround, it every now and again remains ununited in age. Within advanced life a manubrium is once in a while joined to the system by bone. Whilst this will require place, nonetheless, a gaunt tissue is typically merely superficial, a central part of the intervening gristle remaining unossified.

image:Gray118.png Figure Four : Ossification of the breastbone.	image:Gray119.png Figure 5
image:Gray120.png Figure Sise : Peculiarities.	image:Gray121.png Figure 7

Articulations
A breastbone articulates in either side using a collarbone & upper 7 costal cartilages.

Fractures of the Sternum

Fractures of the breastbone are non commons, yet, it will effect from either traumthe like once a driver's chest is forced into a steering column around an accident. The fracture of the breastbone is commonly the comminuted fracture, meaning these are broken into pieces. A usual places of sternal fractures is at a sternal angle.