 Good day everybody. Dr. Sanjay Sanyal, professor, department chair. This is going to be a demonstration of the pirotid region. This is the supine cadaver. This is the right side. I'm standing on the right side and the camber person is also on the right side. What are the boundaries of the pirotid region? Anteriorly, this is the mesetra muscle and this structure that we see here, this is the ramus of the mandible. Posterior superiorly, we have the external artery meatus. Posteriorly, we have the mastoid process and the sternocleidomastoid muscle that we can see here. Superiorly, we have the zygomatic arch. So this is the boundary of the pirotid region. The pirotid fascia is called the pirotidomestetric sheath. It's a very tough structure which was enclosing the pirotid gland, the mesetra muscle and the sternocleidomastoid here. This pirotidomestetric sheath is derived from the investing layer of deep cervical fascia and it completely invoices all these structures. It forms the stallow mandibular ligament. This pirotidomestetric sheath is so tough that if there's any swelling of the pirotid gland, it is intensely painful because of the stretching of the sheath and it is supplied by these nerve fibers that we can see here. These are the fibers of the great auricular nerve which carry pain sensation from the sheath. Now, let's take a look at the parts of the pirotid gland. This portion of the pirotid gland that we can see here, this is the superficial part. This is flat and this is the one which is related to these structures that I mentioned here. There is a deeper portion of the gland which is more wedge-shaped and that is here. And this deep portion of the gland is related to where my finger has gone in. That is the styloid process and the three muscles attached to the styloid process. So these are the two parts and these two parts of the gland are separated by a plane which I'm going to show you a little later. Now, let's take a look at these extra structures that we can see here. This is the pirotid duct, also called the Stensen's duct. This arises from the front of the pirotid gland and it goes over the mesetor muscle and then it pierces this muscle that we can see here. This is the buccinator muscle and when I press, you can see the mouth is moving. It opens opposite the crown of the upper second molar tooth. Sometimes, above the pirotid duct, we can see some extra accessory pirotid gland and we can see it in this cadaver. This is called Sosia parotidis. In this, we can also see another bit of accessory gland located here, just above this portion. So these are accessory. Additionally, this cadaver also has some extra lobules of the pirotid gland located here. Now, let's take a look at the structures which are passing through the pirotid gland. We will go from deep to superficial. So for that, let me just reflect this pirotid gland and we can see this structure here. This is the first structure. This is the continuation of the external pirotid artery and we can see the external pirotid artery is entering into the pirotid gland by dividing into two major terminal divisions. This is the first one. This is the maxillary artery, which enters into the intratemporal fossa and the smaller terminal division is this one here. This is the superficial temporal artery. So this is the continuation of the superficial temporal artery. It supplies the structures of the scalp in the temporal region. It runs in this fascia here. This is called the temporal parietal fascia or the superficial temporal fascia. It divides and supplies the frontal and the parietal parts of the scalp. This is the first structure. The next structure that we can see passing through the pirotid gland is this one here. This is the retromandibular vein. Now, if you take a close look, the retromandibular vein is going inside a space here. This is referred to as the fascia venous plane of Peti and this is used as a surgical landmark to do dissection of the pirotid gland while doing a pirotidectomy without sacrificing the fascia nerve. This retromandibular vein is formed by the union of the superficial temporal vein and the maxillary vein. The superficial temporal vein and the small vein is coming from the intra-temporal region. That is the maxillary vein and that is how the retromandibular vein is formed. The superficial temporal vein also runs with the superficial temporal artery. But here in this case, we can see that it is thrombosed and my finger is tracing the thrombose branches of the superficial temporal vein here. They also run in the temporal parietal fascia. So this is the next structure which is going through the pirotid gland. This retromandibular vein then runs on top of the sternocular mastoid and it meets with the vein from behind the ear called the posterior auricular vein and it forms the external jugular vein which will then open into the subclavian vein near the venous angle. Other structures which go through the pirotid gland are these which I had already mentioned. This is the branch of the great auricular nerve C23 which supply the pirotid sheath and which carry pain fibers and they also supply the skin over the pirotid gland. The next structure which passes through the pirotid gland is this one here. This is the auriculotemporal nerve. The auriculotemporal nerve carries secretor motor fibers to the pirotid gland which came from the glossopharyngeal nerve, tympanic nerve, glissopitrosal nerve and synapse in the aortic ganglion and they supply secretor motor fibers and after that the auriculotemporal nerve which is a branch of the mandibular nerve continues and supplies sensation to the skin of the temporal region. Last but definitely not the least is this structure which I have lifted up here. This is the facial nerve. The facial nerve emerges from the stalomastoid foremen between the mastoid process and the stalate process and we can see two branches of the facial nerve. One is this one here and the other is this one here which I have lifted up and it enters into the pirotid gland from above down and it runs lateral to the retromandibular vein. It breaks up into a plexus here inside the pirotid gland which is referred to as the pest and serenus and from here it divides into two divisions a temporal facial and a cervical facial. Temporal facial gives temporal and psychomatic branches. Cervic facial gives buccal, marginal mandibular and cervical branches and we can see some of the branches here which supplies the platysma muscle. So these are the branches of the facial nerve which go through the pirotid gland. Before I conclude let me mention some important clinical correlations. Pirotid duct, strictures and pirotid duct stones can occur and in which case there will be swelling and pain of the pirotid region and it is diagnosed by a test known as pirotid xylography. We can relate the pirotid duct at its opening opposite the crown of the upper second molar tooth and inject a contrast medium. Breamorphic adenoma of the pirotid gland is also a well-known entity in which case we may have to do a pirotid rectum either a superficial or a complete pirotid rectum. We have to be careful to protect the facial nerve which I showed a little while back and in order to protect the facial nerve we have to dissect in the facial venous plane of petty using the retro mandibular vein as our landmark. Pirotid surgery is the most common cause of facial nerve injury and if the facial nerve is injured then the muscles on the face on that side will be paralyzed. So these are some important clinical correlations pertaining to the pirotid gland. Thank you very much for watching. Dr. Sanjay Sanyal Sanyagot, Mr. Kendal Kamborbatch is the camera person if you have any questions or comments please put them in the comment section below. Have a nice day.