Step 2 - Dissection of the Orbit

Dorsal Approach (cont.)

1. This deeper dissection of the orbit shows the optic nerve, superior oblique muscle, nasociliary nerve and lacrimal artery.
   

2. Laterally you should also identify the lacrimal nerve (branch of ophthalmic), the lateral rectus muscle and the lacrimal gland.   Medially you should look for the trochlear nerve where it enters the superior oblique muscle, the nasociliary nerve, anterior ethmoidal nerve and artery and medial rectus muscle. Anteriorly and medially note how the superior oblique muscle curves back through the trochlea of the superior oblique muscle (not easy to identify) to attach to the eye.
   HINT: To demonstrate the trochlea saw partially through the frontal bone on either side of the orbit and carefully remove this piece of frontal bone by gently tapping on it with the hammer. If the tap is fortuitous, the trochlea will be exposed.

3. Deeper structures that can be identified include the inferior rectus and inferior oblique muscles. Lateral to the optic nerve look for the ciliary ganglion and the short and long ciliary nerves , but they will be difficult to confirm.