Petalia is an anatomic description of cerebral asymmetry where one of the cerebral hemispheres protrudes towards the other hemisphere and thereby causes an impression on the inner surface of the skull 1, 2.

Terminology

The typical configuration in contemporary humans is the combination of a right frontal lobe petalia and a left occipital lobe petalia i.e the right hemisphere protrudes anteriorly beyond the left, and the left hemisphere extends posteriorly beyond the right. CT and MRI studies show that these petalias are more prominent in right handers. The opposite pattern is seen in left-handedness.

A related term, Yakovlevian counterclockwise torque, is a geometric torsion in hemispheres secondary to their asymmetries, where generally the wider right frontal cortex makes a displacement to left and concomitantly the left occipital pole makes a bending towards the right side, also known as occipital bending.  Some studies have shown that petalia and occipital bending has some functional significance and these are more common among patients with psychiatric diseases like major depressive disorder 3, schizophrenia 4, and bipolar affective disorder5 in comparison to healthy controls., Occipital petalia is also as a predictive imaging sign for transverse sinus dominance 3,7.

Share article

Article information

rID: 70145
Section: Anatomy
Synonyms or Alternate Spellings:

Support Radiopaedia and see fewer ads

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.