So that as you look at the surrounding structures, you wanna see the frontal sinus medially

  the ethmoid, and then the sphenoid.

▼去除眶顶即暴露眶骨膜。其内部填满了脂肪。对于穿行于脂肪内的结构我们需要掌握，但同样需要了解一点，即在眶内进行手术时，需要尽可能保留这些脂肪，因为去除脂肪，将使得眶内的肌肉和神经形成疤痕化，从而影响眶内结构的功能。

眼眶手术，神经外科对其作出的一项革新是自动牵开器的应用，这可在术中保留解剖层面的同时保护眶内脂肪而维持重要结构的功能。

And then if you remove the orbital roof you see the periorbita, and inside of this it's filled with fat.And we wanna understand the structures passing through that fat,and also understand that when we're doing orbital surgery，you wanna preserve that fat as much as possible,because if you lose that fat,then the muscles and nerve become scar together and the orbit doesn't function very well.  So for working in the orbit,one of the innovations of brain surgery which are self-retaining retractors become very important in maintaining those surgical planes for surgery while preserving the fat that makes the orbit function as well as it does. 

  Here we see the superior orbital fissure,

   the optic canal

  the sinuses along the medial wall that are routes to the orbit,

  or the lateral orbital wall that provides the route for the lateral orbitotomy.

one of these is the trochlear nerve.

 You can divide the annular tendon here between superior oblique and levator. But if you make an incision, you wanna preserve trochlear nerve.

  And we'll talk about a number of other structures that cross from lateral to medial. Another one is the superior ophthalmic vein that crosses above the optic nerve

  as does the ophthalmic artery.

  And here we're back at the orbital apex.We've divided between the superior and lateral rectus here.You can open the orbital apex from laterally.

  Here we see the frontal branch of V1 pass to the orbit outside the annular tendon.

  But the nasociliary nerve, the branch of V1,passes through the annular tendon,and it's a number of...one of the structures that passes above the optic nerve.

   We see the 6th nerve pass through the annular tendon to the lateral rectus.

  And here's the lacrimal nerve, that passes up to the area of lacrimal gland.

  Here's the ophthalmic artery, which in 90% of cases will pass above the optic nerve from lateral to medial,but in about 10-15% of cases you'll find the ophthalmic artery below the nerve.

  Just another picture we've divided the annular tendon between the lateral rectus that we've folded laterally here.We see the abducens nerve entering it,

  the nasociliary crossing above here the optic nerve,

  as does the frontal branch and the trochlear nerve here.

  Here we see one of the long ciliary branches that carries sympathetics to the globe.

  But here we see the inferior division of the oculomotor nerve that gives rise to the motor, parasympathetic root of the ciliary ganglion in this area.

  And we'll talk a little bit more about that, but you wanna understand the osseous wall as well as the complex anatomy inside the orbit.

  Just when we take off the orbital roof,and open the periorbita,

  the first nerves that we see are trochlear nerve to superior oblique,

  the frontal branch gives rise to supratrochlear and supraorbital,

  and then laterally the lacrimal nerve.

  And then as we go deeper we see the superior ophthalmic vein that passes above the optic nerve.

  And then adjacent it, other structures that pass above the nerve, the nasociliary nerve,and the ophthalmic artery.

  Here we see another nerve that passes below the optic nerve. What is that nerve? That's the branch of the inferior division inferior division of 3rd nerve

  Here we see this branch to the medial rectus again that passes below the optic nerve to reach the medial rectus, the branch of the inferior division.

▼动眼神经下支 支配 内直肌（下图）

   One of the important bits of anatomy, very critical to dealing here at the lateral part of the orbital apex is the origin of the central retinal artery.

  And it's commonly the first branch of the ophthalmic artery before it crosses above the nerve.

  And here just a picture of the central retinal artery. The artery enters through the sheath and then passes forward to the globe. and the center of the optic nerve.

  And just losing that tiny little branch, just get a little bleeding, a little bipolar, and a tiny artery and it's lost and the patient can end up with a blind eye.

▼因此需要特别注意保护视网膜中央动脉，特别在眶尖外侧部、视神经外下侧进行操作时。

  So it's very important to think about saving the central retinal artery in here below and lateral to the optic nerve along the lateral part of the orbital apex.

  As you approach the orbit, and working from the optic canal 

  you can divide the annular tendon mediallybetween the levator and superior oblique.

  But you wanna preserve the trochlear nerve, and here it's been divided with the trochlear nerve preserved.

▼也可在总腱环外侧进行分离，以处理累及眶上裂的病变。但在上睑提肌和外直肌之间分离总腱环外侧时，需将眼上静脉留在外侧。

  You can also divide the annular tendon laterally if you're working with a lesion coming through the superior orbital fissure. But to divide the annular tendon laterally between levator and lateral rectus you wanna let the superior ophthalmic vein go laterally.

  It's quite a large vein, 

  and if you pull it medially with the levator, it blocks access to the orbital apex on the lateral side of the optic nerve.

  So it's better to let that vein go laterally, and let the levator without the vein be retracted medially.

  Here once you open between the levator and here 6th nerve going to lateral rectus, you see the division of the oculomotor into superior and inferior division.

  Those occur below the area of the anterior clinoid.

  the 4th nerve is passing medially.

  And here we see nasociliary nerve pass through the annular tendon above the optic nerve.

  here we see ciliary ganglion.

  Can anyone tell me what nerve that is? That's the sensory root, that's the nerve that carries corneal sensation.It doesn't synapse in the ciliary ganglion.

  But here's inferior division of III. This is the parasympathetic root, the motor root of the ciliary ganglion that controls the pupil.

  Here's just the approach along the medial orbital wall. Here, the trochlea of the superior oblique muscle

 diving in under the superior rectus and attaching to the lateral part of the globe.

  ophthalmic artery

  Here's lacrimal branch going to lacrimal gland that comes from V1.

  But, lacrimation starts back in the facial nerve in the posterior fossa, greater petrosal,to vidian nerve,

  From V2...the V2 gives off the zygomatic nerve that innervates some of the skin around the lateral orbit.

  those parasympathetic branches that get into the zygomatic branch of V2 jump to the lacrimal nerve

  the final pathway for lacrimation then comes through lacrimal nerve.

▼这是上述相关结构的概览，在颅中窝，眼神经的分支进入眶尖，上颌神经沿着眶底外侧走行，下颌神经进入颞下窝。

  you wanna see this all in the context of the adjacent structures,middle fossa,branches of V1 entering the orbital apex, V2 running along the lateral orbital floor, and then V3 here entering infratemporal fossa.

  But as you blow up all of this anatomy where there...there're multiple routes that intracranial pathology can extend to the orbit out of the sinuses, or along the foramen of the cranial nerves, or along the optic canal,to the orbit. And you wanna understand all of these complex relationships.

  then we do just a quick review of cavernous sinus behind with 3rd nerve passing below the anterior clinoid,

  here, 4th nerve, V1,abducens nerve,here passing through the superior orbital fissure

  V2 exiting here middle fossa to run along the floor of the orbit.

  Here we've removed the clinoid. And just under the clinoid here,we see the 4th nerve passing from lateral part of orbital apex,to the medial part to innervate the superior oblique.

  And here we see the division of the 3rd nerve into superior and inferior division, 

  this taking place below the anterior part of the anterior clinoid.

  Here we see another orbital apex, clinoid removed,

  optic canal.

  And then, lateral to the optic canal, we see some of the structures passing through the oculomotor foramen of the annular tendon,and other structures passing outside.

  Here now, we see we've removed the clinoid,the lateral wall of the superior orbital fissure.

  Here you see the oculomotor foramen

  the trochlear nerve passing above the orbital apex,

  frontal nerve passing outside the annular tendon.

 But 6th nerve and nasociliary nerve passing through the lateral edge of the the oculomotor foramen here at the orbital apex.

  Here we retract the frontal nerve.

  You see the nasociliary nerve

  and below it the 6th nerve going to the lateral rectus, 

  and here the division into superior and inferior divisions of 3rd nerve,

  and the trochlear nerve passing medially below the anterior part of the anterior clinoid that has been removed.

  Here we've divided the annular tendon laterally here,

  and we see superior division of 3rd nerve going to levator, superior rectus,

  inferior division going to inferior rectus,inferior oblique,

  giving rise also to the motor parasympathetic root of the ciliary ganglion.

  And here we see the sensory root of the ciliary ganglion that conveys corneal sensation through V1.

  And, some of the branches of nasociliary nerve that carry sympathetic function to the globe.