For positioning purposes, in the average adult skull, the difference between the OML and the IOML is approximately (select one):

a. 5 degrees

b. 7 degrees

c. 10 degrees

d. 12 degrees

b) 7 degrees

Explanation:

The brain scanning techniques like CT and MRI have the reference lines like IOML or Infraorbitomeatal line and OML or Orbitomeatal line. These lines act as the standard reference during the CT techniques based on X-Rays.

The OML line passes through the centre of the external auditory meatus and the canthus of the eye whereas the line drawn between the external acoustic meatus to the infraorbital margin. These lines are used to adjust the positions of the cranium or the skull during the Radio-imaging process. The difference formed between these lines approximately lies between 7-8 degrees.

Thus, 7 degrees is the correct answer.