206 THE FCETUS. 



is formed by the conjunction of the two parietal bones at their supe- 

 rior edges. The fronto-parictal, coronal, transverse or anterior 

 suture crosses the one above mentioned at right angles, at the place 

 where its two halves unite. The occipito-parietal, lambdoidal, pos- 

 terior or occipital suture seems to be only a bifurcation of the 

 sagittal: as the squamous, or temporo-parietal sutures are con- 

 cealed under a thick layer of soft parts, they hardly deserve to be 

 mentioned in a work on midwifery. 



529. The lambdoidal suture, so called from its resemblance to 

 the Greek A is perhaps the most frequent cause of error, as it may 

 be mistaken for the fron to- parietal. It differs from it, however, be- 

 cause its iwo branches, which are oblique to each other and to the 

 sagittal suture, really form two distinct and independent sutures, while 

 the two moieties of the anterior suture are only continuations of each 

 other, and constitute but one and the same line. 



530. There are usually found at the points where these sutures 

 cross or terminate, certain membranous spaces called fontanels or 

 fountains of the brain. 



The anterior or frontal fontanel, which is sometimes called the 

 bregmatic fontanel, because it in fact answers to the bregma, forms 

 the common point of union of four bony angles, viz. the superior angles 

 of the two portions of the frontal bones, and the two antero-superior 

 angles of the parietal bones; it is larger or smaller accordingly as these 

 angles are sharper or rounder; it is of a lozenge shape, and generally 

 extends much farther between the two portions of the coronal than 

 of the parietal bones. 



The posterior, or occipital fontanel, which forms a part of the 

 summit of the head, is situated at the spot where the sagittal loses 

 itself in the lambdoidal suture; it is always very narrow, and in 

 some subjects scarcely distinguishable; its triangular shape pre- 

 vents it from being mistaken for the one before mentioned; but as 

 a middle suture sometimes divides the occipital bone into two 

 pieces, and as the superior angle of this bone is sometimes wanting, 

 it must be remembered that only three branches issue from this fon- 

 tanel, or if there should be four, the two lateral branches proceed 

 obliquely towards the mastoid processes, and do not cross the other 

 at right angles, as is the case at the anterior fontanel. This is the 

 most important fontanel, since it indicates the presence of the sum- 

 mit of tbe head. 



The inferior or lateral fontanels, four in number, two on each 

 side, are found at the points of termination of the anterior and pos- 

 terior sutures, and are of no use in the practice of midwifery. 



531. The head is further divided into five regions or ovals: one 



