SUTURES OF THE SKULL. 175 



perior angle of the occipital. In childhood, and occasionally in the adult, when 

 the two halves of the frontal bone are not united, it is continued forwards to 

 the root of the nose. This suture sometimes presents, near its posterior ex- 

 tremity, the parietal foramen on each side ; and in front, where it joins the 

 coronal suture, a space is occasionally left, which incloses a large Wormian 

 bone. 



The Coronal Suture (fr onto -parietal] extends transversely across the vertex of 

 the skull, and connects the frontal with the parietal bones. It commences at 

 the extremity of the great wing of the sphenoid on one side, and terminates at 

 the same point on the opposite side. The dentations of this suture are more 

 marked at the sides than at the summit, and are so constructed that the frontal 

 rests on the parietal above, whilst laterally the frontal supports the parietal. 



The Lambdoid Suture (occipito-parietaT) so called from its resemblance to the 

 Greek letter A, connects the occipital with the parietal bones. It commences 

 on each side at the mastoid portion of the temporal bone, and inclines upwards 

 to the end of the sagittal suture. The dentations of this suture are very deep 

 and distinct, and are often interrupted by several small "Wormian bones. 



The sutures at the side of the skull are also three in number; the spheno- 

 parietal, squamo-parietal, and masto-parietal. They are subdivisions of a single 

 suture, formed between the lower border of the parietal, and the temporal and 

 sphenoid bones, and which extends from the lower end of the lambdoid suture 

 behind, to the lower end of the coronal suture in front. 



The Splieno-parietal is very short ; it is formed by the tip of the great wing 

 of the sphenoid, which overlaps the anterior inferior angle of the parietal 

 bone. 



The Squamo-parietal, or squamous suture, is arched. It is formed by the 

 squamous portion of the temporal bone overlapping the middle division of the 

 lower border of the parietal. 



The Masto-parietal is a short suture, deeply dentated, formed by the posterior 

 inferior angle of the parietal, and the superior border of the mastoid portion of 

 the temporal. 



The sutures at the base of the skull are, the basilar in the centre, and on 

 each side, the petro-occipital, the masto-occipital, the petro-sphenoidal, and the 

 squamo-sphenoidal. 



The Basilar Suture is formed by the junction of the basilar surface of the 

 occipital bone with the posterior surface of the body of the sphenoid. At an 

 early period of life, a thin plate of cartilage exists between these bones ; but in 

 the adult they become fused into one. Between the outer extremity of the 

 basilar suture, and the termination of the lambdoid, an irregular suture exists, 

 which is subdivided into two portions. The inner portion, formed by the union 

 of the petrous part of the temporal with the occipital bone, is termed the petro- 

 occipital. The outer portion, formed by the junction of the mastoid part of the 

 temporal with the occipital, is called the masto-occipital. Between the bones 

 forming the petro-occipital suture, a thin plate of cartilage exists ; in the masto- 

 occipital is occasionally found -the opening of the mastoid foramen. Between 

 the outer extremity of the basilar suture and the spheno-parietal, an irregular 

 suture may be seen, formed by the union of the sphenoid with the temporal 

 bone. The inner and smaller portion of this su'ture is termed the petro-sphe- 

 noidal; it is formed between the petrous portion of the temporal and the great 

 wing of the sphenoid ; the outer portion, of greater length, and arched, is 

 formed between the squamous portion of the temporal and the great wing of 

 the sphenoid ; it is called the squamo-sphenoidal. 



The cranial bones are connected with those of the face, and the facial bones 

 with each other, by numerous sutures, which, though distinctly marked, have 

 received no special names. The only remaining suture deserving especial con- 

 sideration, is the transverse. This extends across the upper part of the face, 



