 Dr. Sanjay Sanyal, Professor Department Chair. We are going to demonstrate the accessory structures of the eye. We have dissected out the skin over the orbit and the eyelids and you can see muscles here which are surrounding the eyeball. This is the orbicularis oculi. These are the orbital parts of the orbicularis oculi. This and on the lid we have the palpibril part of the orbicularis oculi. On the medial side of the eye, there is a tough ligament structure which is known as the medial palpibril ligament or the medial canthal ligament which is caused by the fusion of the two tarsal plates. And similarly on the lateral side there is another ligament which is called the lateral palpibril ligament or the lateral tarsal ligament. Orbital fibers of the orbicularis oculi they take attachment on the medial side and they go all the way around and they come and get attached again to the medial canthal ligament. The palpibril fibers they take attachment from the medial canthal ligament and they circle and they get attached to the lateral canthal ligament. So both the upper and the lower. The orbital fibers are responsible for closing the eyelid tightly and the palpibril fibers are responsible for closing the eyelids gently. This is the palpibril fissure, the space between the upper and the lower eyelid. The portion above the palpibril fissure is supplied by the temporal branch of the facial nerve and the portion below is supplied by the zygomatic branch of the facial nerve. When we have paralysis of the facial nerve branch then the lower eyelid falls down like this and therefore there is overflow of tears and that is known as epifuria and this is known as ectropion. Similarly the person will not be able to close his eyelids and therefore they will be rolling up of the eyeball and that is known as Bell's Phenomenon. Now let's come to the layers of the eyelid. If you pick up the eyelid here you will feel that it's got a tough structure and that is known as the fibrous skeleton of the eyelid and it is composed of a fibrous structure called the tarsal plate. The tarsal plate is attached to the superior orbital margin through the orbital septum and inferiorly it's attached to the inferior orbital margin through the orbital septum. On the outer surface we have the skin here and you can see the skin is so thin it is loosely attached and this is the place where we have collection of blood and fluid in echymosis and in edema. Then I've already described to you the palpibril muscles. Then we have the tarsal plate. Attached to the inner margin of the tarsal plate we have a series of glands and they are known as the tarsal glands or the Bebovian glands and they release a secretion on the late margin and finally we have a layer of conjunctiva which is called the palpibril conjunctiva. So these are the layers of the eyelid. On the free margin of the eyelid we can see these eyelashes. These are known as the cilia and there are some glands which are related to the cilia which are known as the ciliary glands or the Zeiss glands. Inflammation of the Zeiss glands produce what is known as stye also known as hodulum external. While inflammation of the tarsal glands or the Bebovian glands produces what is known as chelation or hodulum internal. These are some of the finer points about the eyelid and the muscles of the eyelid. There is one more muscle which is called the levator palpibril superioris which we will dissect out later but it is not visible in this dissection. Let's take a look at how the tears are drained. If I close both the eyelids then the space between the eyelid and the eyeball is called the congenital sac. The robe has gone into this space here. This is the superior congenital formings and this is the inferior congenital formings. The lacrimal gland is located deep in this region. So the tears come out from here. They drain the surface of the eye and then they go to the medial canthus of the eye and then they drain through the lacrimal lake here. So this is the flow of drainage of tears and for this to happen the eyelid has to blink approximately 15 to 20 times every minute and failure to do so will lead to dryness of the eye and will lead to corneal abrasion. When we are talking about the drainage of tears, if you take a close look at the upper eyelid near the medial canthus there is a small elevation. This is known as the superior lacrimal papilla and at the tip there is a small opening that is the lacrimal punctum and my probe has gone into the punctum. In the medial canthus of the lower eyelid, we will see yet another small elevation which is known as the inferior lacrimal papilla and at the tip there is another opening that is the inferior lacrimal punctum. From each of these punctum, one small duct will go like this medially towards the canthus that is known as the superior lacrimal canaliculus and the inferior lacrimal canaliculus and both of them will then converge behind the medial palpable ligament in a small sac called the lacrimal sac and from there the fluid will then drain into the inferior nasal mediators. The passage from the lacrimal sac to the inferior nasal mediators is known as the nasal lacrimal duct. The superior and or the inferior lacrimal canaliculi can get blocked by epithelial debris or otherwise and then the patient will complain of overflow of tears and therefore as a small OPD procedure we do what is known as lacrimal syringe and for that we identify the superior and the inferior punctum and we cannulate it and we inject it with seline. Once we inject it we should ideally go through the lacrimal canaliculi into the lacrimal sac and from there the fluid should come out into the nose. That process is called lacrimal syringine and it is used as a diagnostic as well as a therapeutic procedure in case of blocked nasal lacrimal passage. This is the phase two of our dissection of the orbit and eyeball. We have completely removed the orbicularis oculi muscle from the orbit. Once we reflect the orbicularis oculi we notice that on the medial side both of them are attached to one tough ligament. This is known as the medial palpable ligament. This is formed by the fusion of the two tarsal plates and likewise on the lateral side also we can see the lateral palpable ligament much more clearly which is attached to the lateral orbital margin. So these two ligaments provide attachment to the peculiaris oculi. Now let me reflect superior fibres and after separating the eyeball from the orbit what are the structures we notice? We have removed most of the periorbital fascia and the retrobulbar fat and we notice this structure here. This is the lacrimal gland. This is the orbital part of the lacrimal gland and we can see this muscle here. This is the levator palpable braze superioris muscle which is splitting it into an orbital part and we can see the palpable part of the lacrimal gland here. This is the one which is in relation to the lig.