Handout on parietal bone : brief and easy description

Parietal bone

1.       Anatomical points:

·   Superior border is longest, thickest and serrated,

·   Superior border  lies in median plane

·    ** Anterior  inferior angle is acute and internally marked by groove for anterior  division of middle meningeal vessel 

2.       Morphological type : Flat bone

3.       Structure of bone : inner and outer table(compact bone )  and middle diploe (spongy bone)

4.       Ossification : intra membranous ossification

5.       Development : neural crest

6.       Parts:  identify

·         four borders:

a)       superior border : longest, thickest and serrated and internally marked by a sulcus known as sagittal sulcus which lodges superior sagittal sinus , Granular pit present side of sagittal sulcus which lodge arachnoid granulation

b)      inferior border irregular and serrated and internally marked by posterior division of middle meningeal artery (at the middle of inferior border )

c)       anterior and posterior border are straight and serrated

·         superior border is articulated with opposite parietal bone formed sagittal suture

·         Anterior border is articulated with frontal bone formed coranal suture

·         Posterior border is articulated with occipital bone formed lambdoid  suture

·         Inferior border is articulated with

a)      Greater wing of sphenoid bone

b)       Squamous part of temporal bone

c)        Petrous part of temporal bone .

·         What is pterion ?

·         Ans : union between four bones

a)      Frontal bone

b)      Anterior inferior angle of parietal bone

c)       Greater wing of sphenoid

d)      Squamous part of temporal bone  

e)      What is the importance of pterion ?

f)       Internal surface of pterion is lodged by anterior division of middle meningeal artery 

·         Four angles :

a)      Anterior superior angle forms bregma

b)      Posterior superior angle forms Lambda ( in children it is called pesterior frontanelle )

c)       Anterior inferior angle forms pterion and internally marked by groove for anterior division of middle meningeal artery

d)      Posterior inferior angle forms asterion and internally a groove present which lodges sigmoid sinus

External Surface of parietal bone :

·         parietal tuberosity : maximum transverse diameter of skull measures by these points

·         Superior and inferior temporal line

Internal surfaces of parietal bone :

·         impression of sulci and gyri of cerebrum

·         impression of anterior division of middle meningeal artery at internal surface of anterior inferior angle

·         impression of posterior division of middle meningeal artery at middle of inferior border

·         sagittal sulcus near the superior border

·         sulcus for sigmoid sinus near the posterior inferior angle

7.       Identify the groove for middle meningeal vessels: identify, origin of middle meningeal vessels,

8.       Through which opening, middle meningeal vessel is enter into cranial cavity? 

Ans: Foramen spinosum