Coronal CT of the sinuses

1. A Crista galli.

2. B Right infraorbital foramen.

3. C Right inferior turbinate.

4. D Hard palate.

5. E Right infraorbital nerve, artery or vein.

‘Crista galli’ is Latin for ‘crest of the cock’. It is a midline ridge of bone that projects from the cribriform plate of the ethmoid bone. The falx cerebri attaches here, and the olfactory bulbs lie on either side. The infraorbital foramen transmits the infraorbital nerve, artery and vein, which can be damaged or compressed in orbital blowout fractures. The infraorbital nerve is a branch of the maxillary nerve, which is the second division of the trigeminal nerve (CN V).

There are three turbinates; superior, middle and inferior. They function to control the flow of air and ensure that even air humidification and warming takes place over an increased surface area. The osteomeatal complex is a functional entity that includes the middle turbinate, uncinate process, bulla ethmoidalis, hiatus semilunaris and ethmoid infundibulum. It is the common pathway for drainage and ventilation of the frontal, maxillary and ethmoid sinuses.

MR angiogram of the neck

1. A Right vertebral artery.

2. B Right common carotid artery.

3. C Right internal thoracic artery.

4. D Left common carotid artery.

5. E Left vertebral artery.

The paired vertebral arteries are branches of the first part of the subclavian arteries and course through the transverse foramen of each cervical vertebra from C6 to C1. After C1, the vertebral arteries pass through the suboccipital triangle and enter the foramen magnum.