510 ANATOMY IN A NUTSHELL. 



The external surface of the parietal bone has the following points: 



1. Parietal emineni e near the center of the bone where ossification com- 

 mences. 



2. TWO SEMICIRCULAR TEMPORAL RIDGES which are about two-fifths of an 

 inch apart ami arc continuous with the ridges on the frontal bone, and like 

 those on the frontal bone give attachment to the Temporal muscle and to the 

 temporal fascia. 



:!. The surface below these ridges gives attachment to part of the 

 Temporal muscle. 



4. The parietal foramen is near the superior border and transmits a 

 vein to the superior longitudinal sinus. Occasionally a branch of the occipital 

 artery passes through this foramen. This foramen is inconstant. 



The internal surface of the parietal hone is concave 1 and has the following 

 points: 



1. Eminences and depressions for the cerebral convolutions. 



2. Furrows for the middle meningeal artery. 



3. A oi;oo\ i.. which with its fellow. Lodges the superior longitudinal sinus. 

 There i- also a groove for the lateral sinus at the posterior inferior angle. 



The superior border is dentated and with its fellow forms a sagittal 

 suture, which is a synarthrosis joint. This border is the longest and thickest 

 of the four borders. 



The anterior border joins the frontal bone and helps to form the coronal 

 suture. 



Tin-; POSTERIOR BORDER joins the occipital bone and helps to form the 

 Lambdoid suture. 



Tin: [NFERIOR BORDER is divided into the following parts, (a) the anterior. 

 which is overlaped by the tip of the greater wing of the sphenoid, (b) the middle 

 part which i> overlaped by the squamous portion of the temporal bone, and 

 (c) the posterior pari which articulates with the mastoid process of the temporal 

 bone. 



Tin. INTERIOR SUPERIOR ANGLE is the point where the two parietal bones 

 meel the frontal hone. This is the location of the anterior fontanelle which 

 is called the -oft spol in the baby's head. 



Tin-: posterior superior axoi.k is the point where the two parietal bones 

 ami the occipital hone meet-. This is the location of the posterior fontanelle. 



Tin. posterior [NFERIOR vngle joins the mastoid process of the temporal 



hone. 



'I'm. INTERIOR [NFERIOR ANGLE joins the frontal hone and greater wing of 

 the sphenoid hone. 



OSSIFICATION. — This bone ossifies from one center. 



Artn i lation. It articulates with. (1) the opposite parietal bone. (2) the 

 occipital bone. (3) the frontal. (4) the temporal, and (5) the sphenoid, thus 

 making five bone-. 



Attachment of Mi s< les. This bone has but one muscle attached to it, 

 the Temporal. See page 508 



Blood Supply. Middle meningeal, occipital, supraorbital arteries. 



