 So this is a demonstration of the Infrahyde and the suprahyde strap muscles the neck and a few structures in the anti-survival region This is the right side of the cadaver. This is the left side of the cadaver on this side We have reflected the sternocleidomastoid on the right side left side is still intact So let's take a look at what are the infrahyde strap muscles that we can see here This is the sternohyoid It has been partially cut while they were doing the embalming of the cadaver So it extends from the manabrium sterni all the way to the hyoid bone So this is the sternohyoid on the right side and this is the sternohyoid on the left side Which also has been partially damaged in the process of embalming So this is the superficial intra-hyoid strap muscle once we reflect This muscle we can see the second one This is the sternothyroid and this is it inserted onto an oblique line on the thyroid cartilage This is on the right side and when I lift this up we can see the sternothyroid on the left side That's the next deep and above the sternothyroid we have the next muscle that we can see here This is the thyroid hyoid which also starts from the oblique line of the cartilage and gets inserted on the hyoid And on the left side also we can see the thyroid hyoid And the final the most superficial of the strap muscle That we can see is this one This is the omohyoid And we can see the omohyoid has got two bellies The inferior belly of the omohyoid starts from the scapula There's an intermediate tendon here And this intermediate tendon is attached by means of a facial sling which we have retained And it is attached to the clavicle which we have reflected here And this is the superior belly of the omohyoid And we can see the superior belly of the omohyoid goes up and it gets attached to the Again to the hyoid bone So this is the omohyoid and this forms a boundary of many triangles that we have already seen on this side We can see a little bit because we have not reflected the sternocleomastoid We can see only the superior belly of the omohyoid getting inserted So these are the intrahyoid strap muscles The intrahyoid strap muscles are located in the muscular triangle or the so-called omotracheal triangle And they are all covered by the muscular part of the retracal pressure Now in this connection there is a very important clinical correlation The muscular part of retracal fascia They all get attached to the manubrium sternum because these muscles also get attached to the manubrium sternum So therefore there is no space potential space or otherwise between the muscular part of the retracal fascia and the thoracic cavity On the other hand There is another part of the retracal fascia which covers the thyroid gland here And we can see a little bit of the thyroid gland under here. This is the thyroid gland And the trachea that is called the visceral part of retracal fascia And the visceral part of retracal fascia extends all the way down into the anterior and to the superior media sternum So there is a potential space And my finger has gone into that potential space. It has gone into the superior media sternum So therefore infection in the visceral pre tracheal space From the neck Can travel into the anterior and to the superior media sternum where my finger is gone in So this is one root of spread of infection from the neck to the chest Next thing which I wanted to point out to you is that this intra-iron strap muscles. They are all supplied by branches of the Absorcer vicaris and we can see some of the neuro vascular partials which we have retained here These are the branches which are supplied the point to be remembered is that all these nerves They all come the muscles from below up and they supply the deep aspect of the muscles When we are doing a thyroid surgery We have to cut these strap muscles And we have to reflect them only then we can expose the full thyroid which is here Because the nerve supply is from below up if we cut these strap muscles lower down We will denovate the upper part of the muscle So therefore these muscles should be cut as high as possible So that the minimum portion of the muscle is denoved What is the function of the infrared strap muscles the infrared strap muscles as the term implies They either depress the higher bone or they fix the higher bone and by so doing they enable the supra higher muscles to work better And the action of the supra higher muscles is in deglutition and in mastication They help to lower the mandible and they also help in swallowing. So that brings me to the supra higher muscles that we can see here We cannot see all the supra higher muscles because the Submandibular salivary gland is very enlarged in this patient and we'll have to dissect it out But we can see some of the supra higher muscles for that We'll have to look on the under surface of the chin and if you look very closely here We can see one muscle here on this side Which I have lifted up and we can see the same muscle on this side also which I have lifted up This is the anterior belly of digastric This is the anterior belly of digastric on the left side and this is the anterior belly of digastric on the right side And we can see that both of them are meeting at an apex near the symphysis mentai And at the base this is the higher bone So therefore this is the submental triangle Which is shared by both the sides And the floor of the submental triangle is formed by this muscle here where my finger is located And that floor is the Mylohyde muscle with the median raffae in between So this is the submental triangle And what are the contents of the submental triangle? One content we can already see right now here in front of us This is these other Beginning the origin of the submental vein And we can see that there are not one but there are several The submental veins start in the submental region and they all travel down And as they travel down they have a communication with the facial vein and we can see that very clearly on the right side Not only that The submental veins and the lower part of the neck they form what is known as an anterior jugular vein on the right side And an anterior jugular vein on the left side and we can see that here We can see the right anterior jugular and the left anterior jugular These are all located in the muscular triangle or the omotracheal triangle and then In the suprasternal space of burns which is located here The two sides Establish a communication with each other and that is known as the jugular venous arch and we can see that here And then after that each anterior jugular vein Goes to the lateral cervical region and it opens into the external jugular vein But in this patient as I mentioned earlier, there is no external jugular vein So they open directly into the subcaven vein in this patient So this is the course of the anterior jugular vein and their formation So these are the structures that we can see here in the anterior cervical region Especially in the muscular triangle And the final point is that one of the most important contents of the muscular triangle or the omotracheal triangle is the thyroid gland And we can see the thyroid gland here, which is covered by the Visceral layer of the pre tracheal fascia Thank you very much for watching. If you have any questions, please put them in the comment section below Dr. Sanjay Sanyal signing out