126 



A MANUAL OF ANATOMY 



The spheno-parietal suture connects the posterior part of the 

 superior border of the great wing of the sphenoid with the antero- 

 inferior angle and anterior part of the inferior border of the parietal 

 bone. Its direction is from behind forwards. Posteriorly it is 

 continuous with the parieto-squamosal suture, and anteriorly with 

 the spheno-frontal suture. The spheno-parietal suture, like the 

 parieto-squamosal, is a squamous suture. The region of the spheno- 

 parietal suture coincides with the pterion. The spheno-parietal 

 suture may be very short, or entirely absent, in which latter case 

 the lower and posterior part of the frontal bone articulates directly 

 with the squamous part of the temporal bone, thus excluding the 

 antero-inferior part of the parietal bone from any articulation with 

 the great wing of the sphenoid. In such cases the pterion is 

 situated at the posterior end of the spheno-fronal suture. In all 

 cases the guide to it is the lower end of the posterior border of the 



Abnormal. Normal. 



Fig. 79. — Sutures of Right Lateral Surface of Skull. 



S.P., Spheno-parietal; S.F., Spheno-frontal; P.S., Parieto-squamosal; 

 X, Pterion; C, Coronal; S.S., Spheno-squamosal. 



external angular process of the frontal bone, the pterion being 

 situated about i| inches behind it, and about 2 inches above the 

 zygomatic arch. The pterion indicates the situation of the antero- 

 lateral or sphenoidal fontanelle of early hfe. In this region a Wormian 

 bone, called the epipteric bone, is sometimes met with. 



The fronto-squamosal suture is not constant. When present, it 

 connects the lower and posterior part of the frontal bone with the 

 upper and anterior portion of the squamous part of the temporal 

 bone. Its direction is vertical, and it is usually continuous with 

 the terminal part of the coronal suture. It excludes the antero- 

 inferior part of the parietal bone from any articulation with the 

 great wing of the sphenoid. 



The spheno-frontal suture, which is a squamous suture, connects 

 the superior border of the great wing of the sphenoid bone with the 

 lower part of the lateral aspect of the frontal bone. Posteriorly it 

 is continuous with the spheno-parietal suture, and in cases where. 



