All the following statements regarding an exact pa projection of the skull are true excepta the orbitomeatal line is perpendicular to the ir. b the petrous pyramids fill the orbits. c the midsagittal plane (msp) is parallel to the ir. d the central ray is perpendicular to the ir and exits at the nasion.

C. the midsagittal plane (MSP) is parallel to the IR.

Explanation:

All the statements regarding an exact PA projection of the skull are true except that the midsagittal plane (MSP) is parallel to the IR. The skull PA view is a non-calculated PA radiograph of the skull. This view gives a review of the whole skull as opposed to endeavoring to feature any one locale. The PA view diminishes the radiation portion to the eyes contrasted and the AP see less amplification of the facial bones contrasted and the AP view cover of facial bone structures makes it harder to assess the sinuses than with a calculated view.

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?