. Cunningham's Text-book of anatomy. Anatomy. 110 the seventh and eighth, which are usually the longest, are from two and a half to three times the length of the first and twelfth ribs respectively. The shafts are curved so as to adapt them to the form of the thoracic wall. More acute in the upper members of the series, where the shafts are shorter, the curve opens out in the middle and lower parts of the thorax, where the diameters of that cavity are greater. The curve, however, is not uniform. Including the whole length of the bone, it will be seen to be most accentuated towards
. Cunningham's Text-book of anatomy. Anatomy. 110 the seventh and eighth, which are usually the longest, are from two and a half to three times the length of the first and twelfth ribs respectively. The shafts are curved so as to adapt them to the form of the thoracic wall. More acute in the upper members of the series, where the shafts are shorter, the curve opens out in the middle and lower parts of the thorax, where the diameters of that cavity are greater. The curve, however, is not uniform. Including the whole length of the bone, it will be seen to be most accentuated towards the posterior part, where, in correspondence with the point at which the bend is most pronounced, there is a rough ridge placed obliquely across the outer surface of the shaft for the attachment of the Head Neck Tubercle slips of the ilio-cos- talis muscle; this is the angulus costae. The distance between the angle and the tubercle is greatest on the eighth rib; above that, the width between these two points gradually decreases until, in the case of the first rib, the two coincide. Below the level of the eighth rib the distance slightly diminishes in con- formity with the general narrowing of the thorax below that level. Towards the anterior extremity of the rib where the digitations of the serratus anterior and external oblique muscles are attached to its outer surface the curve of the shaft is somewhat more pronounced, and is referred to as the anterior angle. Combined with this curve, there is in many of the ribs a twist. This may best be understood if the student will take a strip of stiff paper and bend it in the form of the curve of the rib. If, after he has done this, he pulls down the anterior end and turns up the posterior end of the strip, he will have imparted to the strip of paper a twist similar to that met with in the rib. This appearance is best seen in the middle members of the series, notably in the seventh and eighth ribs, above and below which it gradually be
Size: 2611px × 957px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
