Can you identify the pituitary gland? Note its relationship to the sphenoid sinusCan you identify the midbrain, pons and medulla on this mid-sagittal sequence.PonsMedullaPituitaryS

Can you identify the corpus callosum and the cerebellum?Corpus callosumcerebellum

This is a coronal T1 weighted sequence through the brain.Can you identify the lateral ventricles?What are these glandular structures noted laterally (red arrows)?

Parotid glands

What is this bony structure (red arrow)? See the adjacent muscular attachments.What are these circular low signal structures (yellow arrows). Hint flowing blood can look like low signal, sometimes called flow voids.Cavernous carotidsMandible

What is this large are of signal void, in the middle of the image (arrows)?Sphenoid sinusHint, air produces no signal.

What is this muscular structure (yellow arrows)?This is the tongue. Do you see the areas of high signal in the muscle. We always see fat (high signal on T1) in the tongue

Can you identify the maxillary sinuses?Hint, air filled sinuses will produce no signal Can you identify the maxillary sinuses?Hint, air filled sinuses will produce no signal Can you identify the nasal turbinates?

Now lets take a look at the orbits. Try and pick out the optic nerve, superior rectus, superior oblique, medial, lateral and inferior rectus extra-ocular muscles. The inferior oblique muscle is note seen on these images.Blue=optic nerve, White=inferior rectusRed=medial rectus, Yellow=superior obliqueGreen=superior rectus, Pink=lateral rectusReview the innervation of the these muscles. Which 2 muscles are not innervated by the oculomotor nerve (III)

Superior oblique trochlear nerve (IV)Lateral rectus Abducens nerve (VI)

What is the signal void over the orbits (arrow)?Frontal sinuses

These are coronal contrast enhanced images, do you see the carotid arteries in the cavernous sinuses.Note the venous blood in the sinuses is slow flowing and in bight on these images but the blood in the carotid arteries is fast flowing and it shows up as signal void.Cavernous sinusesCarotids

Now we are out of the cavernous sinus. Do you see the abnormal enhancing lesion in this case?

Can you identify the mandible?What are the muscles attached to the inside and the outside of the mandible?

Masseter muscle

Medial pterygoid muscle

Do you see the right parotid gland?Why dont you see the left parotid gland? (was he born without one)Unlikely, his head is just tiled in the MRI scanner so the left one is out of the plane

Can you identify the air filled spaces (areas of signal void) on this image?

Mastoid air cells NasopharynxMaxillary Sinuses

What is this blood filled normal venous structure?Transverse sinuses

What extra-ocular muscles do you see on this image?

Inferior rectus on the right (yellow arrow)Lateral rectus on the left (red arrow)

Do you see any areas of abnormal enhancement?

This is the lesion, adjacent to the cavernous extending to the orbital apex

What extra-ocular muscles can you identify on the right?Do you see the optic nerve?Medial rectus blue arrowLateral rectus red arrowOptic nerve pink arrow

Can you identify the frontal sinuses and the sylvian fissures.Frontal sinuses pink arrowsSylvian fissures blue arrows