34 



UOXES OF THE HEAD. 



ment to the rectus capitis lateralis muscle ; and superiorly a deep groove 

 for the lateral sinus l^efore it terminates in tbc jugular notch. 



The basilar ijrocess, or basi-occipital, projects forwards and 

 upwards into tlie middle of the base of the skull. It increases in thick- 

 ness and diminishes in breadth towards its extremity. Inferioriy it 

 gives attachment to the rectus capitis anticus major and minor muscles 

 and the fibrous band of the pharynx. Its superior surface presents a 

 smooth depression, the basilar groove, which su|>ports the medulla 

 olilongata, and close to each lateral margin a slight grooved mark, 

 which indicates the place of the inferior petrosal sinus. 



THE PARIETAL EONES. 



The parietal "bones form a considerable part of the roof of the' skull. 

 They have the shape of quadrilateral plates, convex externally, concave 

 internally. They are a little broader al)ove than below, and the anterior 

 inferior angle is the most projecting. They articulate witii each other 

 in the middle line, with the frontal bone anteriorly, the occipital 

 posteriorly, and the temporal and sphenoid below. 



On the outer .airfare, near its middle, a more marked convexity 

 exists forming the jmrmal eminence. Below this is a curved line, 



Fig. 29. 



Fig. 29. — External surface 



OP THE RIGHT PARIETAL. 



Bone. (A. T.) I 



1, posterior superior angle ; 

 2, anterior superior angle ; 3, 

 posterior iufei'ior angle ; 4, 

 anterior inferior angle, articu- 

 lating with the great wing of 

 the sphenoiil bone ; from 1 to 

 2, superior border in the 

 sagittal suture ; from 2 to 4, 

 anterior bonier in the coronal 

 suture ; from 1 to 3, posterior 

 border in the laml)doidal su- 

 ture ; from 4 to 6, margin of 

 the squamous suture ; from 3 

 to 6, the additamentum su- 

 turaj squamospe; 5, the tem- 

 poral or semicircular line above 

 which is the parietal eminence ^ 

 8, parietal foramen. 



the parietal part of 

 * the temporal ridge, 



bounding a surface 

 somewhat flatter than the rest, 2^^annm iemporale, which forme part of 

 the temporal fossa. Near the posterior and upper angle, is ili3 small 

 parietal foramen. 



The concave inner surface is marked by shallow depressions corre- 

 sponding Avith the convolutions of the brain, and by narrower furrows 

 branching upwards and backwards from the lower border for the middle 

 meningeal vessels. The largest of these grooves running from the 

 anterior inferior angle is sometimes converted into a canal for a short 

 distance. A slight depression along the inner part of the superior 

 border, forms with the one of the opposite side, the groove of the 



