 Hi there and welcome to our latest video this time on the Triangles of the Neck. These triangles were defined long ago when surgical dissection was the only way to investigate anatomy. These days they are less clinically relevant but they are still useful in discussing discrete anatomy and for simplifying the communication of pathology in some domains. The trick is to know thoroughly the origin path and insertion of a select handful of muscles and once you have them in your mind picturing the triangles becomes a breeze. So we'll start off with the anterior triangle. Its medial border is the midline of the neck. Its superior border is the mandible all the way back and the lateral border is the sternocleidomastoid muscle. Super simple as you can see think jawline, midline and then sternocleidomastoid. I'm going to highlight now the digastric muscle, Latin for two bellies which is very important for the next two internal triangles of the anterior triangle which we'll discuss. Let's talk about the submandibular triangle first, superior border of which is the mandible. The medial border is the anterior belly of the digastric and the lateral border is the posterior belly of the digastric. Inside the submandibular triangle is the submandibular gland. So we've now defined the anterior triangle borders and within that the submandibular triangle. We'll use the digastric again to mark a border of our next triangle, the submental. Again mandible, anterior belly of the digastric and then the hyoid bone. And I'm drawing in the midline of the neck as the medial border but this is actually considered one triangle across to the other anterior belly of the left digastric. Inside the submental triangle is the submental lymph nodes. Okay moving laterally now let's talk about the carotid triangle which again utilizes the posterior belly of the digastric, the sternocleidomastoid and then another muscle that we'll be hearing about a bit in this video, the omelhyoid. Inside the carotid triangle is the carotid sheath which contains the common carotid artery among other things, cranial nerve 12, the hypoglossal and the ancestor cervicalis which is a bunch of nerves that supply muscles in this area. Okay we've almost completed the components of the anterior triangle now we've got this one patch inferiorly that is yet to be filled and that's known as the muscular triangle. The borders of that being the hyoid bone, the omelhyoid again, the sternocleidomastoid and then the midline of the neck and in here we have the thyroid and the parathyroid glands. So that's the muscular triangle, the last of the internal triangles within the anterior triangle of the neck. Okay now let's move posteriorly and I'm going to highlight here that muscle we've mentioned a few times the omelhyoid. Let's define the borders of the posterior triangle, trapezius posteriorly, the sternocleidomastoid anteriorly and then a bit of the clavicle as well. The posterior triangle is divided into two discrete triangles separated by the omelhyoid muscle. The inferior portion of the posterior triangle is called the supraclavicular triangle, the borders of which are the omelhyoid, sternocleidomastoid and the clavicle and within here we find the supraclavicular lymph nodes. Last but not least we have the occipital triangle, ordered by the omelhyoid, trapezius and sternocleidomastoid and within there we'll find cranial nerve 11, the accessory nerve, supraclavion artery, external jugular vein and the trunks of the brachial plexus. That's the occipital triangle and that's it for the triangles of the neck. I hope you found that useful, make sure to hit subscribe and we'll see you next time.