 Hello everyone, welcome back to another session in dentistry and more. So today we have a very important but a very small topic in human anatomy that is carotid sheath which is a frequently asked shop not in university exam. So let us learn about carotid sheath. Carotid sheath it is an anatomical term for the fibrous connective tissue that surrounds the vascular compartment of the neck. So it is a part of the deep cervical fascia of the neck. So deep cervical fascia of the neck which includes four layers that is the first layer superficial to deeper layer. So this is a superficial layer and this is the deepest layer. So superficial and deepest layer. The superficial layer is a first layer is a investing layer. The first layer is known as investing layer which surrounds the sternocleidomastoid and trapezius muscle. So it is sternocleidomastoid and trapezius that is the investing layer. The second layer is the current topic that is a carotid sheath. So which encompasses the vascular region of the neck. So this is the vascular region of neck. The second or our current topic that is carotid sheath. The third layer is known as pretracheal fascia which encloses the visceral regions. So the third layer is visceral region of neck. And the lastly the fourth facial layer is pre vertebral fascia which surrounds the vertebral regions of the neck. So the first layer investing layer which surrounds the sternocleidomastoid and trapezius muscle. So it is a superficial layer. The second layer is vascular component that is carotid sheath. The third layer is pretracheal which encloses the visceral regions of neck. And the fourth layer is pre vertebral fascia which surrounds the vertebral region of the neck. So the carotid sheath itself is an accumulation of three of the layers of deep cervical fascia. These layers includes the investing fascia, then the pretracheal fascia and the pre vertebral fascia. So carotid sheath has basically four major structures. Four structures in the carotid sheath. So which are the structures? The first one is common carotid artery and internal carotid artery. This is common carotid artery and internal carotid artery. Then there is internal jugular vein and there is vagus nerve which is a tenth cranial nerve and also deep cervical lymph nodes. So these are the four structures which is present in carotid sheath. And the carotid artery which lies, this is a medial site, this is lateral site anterior and posterior site. So the carotid artery lies medial to the internal jugular vein. And the vagus nerve which is posterior to these two vessels that is carotid artery and internal jugular vein. So this is at a posterior position, this is a medial position and lateral position. And in the upper part, this carotid sheath also contains glosopharyngeal nerve, glosopharyngeal nerve, the accessory nerve and hypoglasal nerve which pairs the fascia of carotid sheath. So these are at the upper part, at the upper part that is 9, 11 and 12. So these three nerves facing the carotid sheath at a upper position. So the carotid sheath basically fuses with pretracheal fascia and investing fascia under sternocleidomastoid. So it fuses with pretracheal and investing layer underneath sternocleidomastoid. And the answer cervicalis is present in carotid sheath over the internal jugular vein. So that was about carotid sheath, it is a very small topic. Only thing we need to learn the four basic layers of cervical fascia of neck. Investing layer, carotid sheath, the pretracheal fascia and pre-vertebral fascia. The first layer is enclosing sternocleidomastoid entropiesis, then the vascular component, visceral component and vertebral component from superficial to deep layer. And the main point is the four structures which is presented carotid sheath that is common and internal carotid artery, common carotid artery and internal carotid artery, then internal jugular vein, vagus nerve and deep cervical lymph nodes. And it fuses with pretracheal fascia and investing fascia under sternocleidomastoid. And also ancestral vagalis is present in carotid sheath over internal jugular vein. So that is about carotid sheath, I will come up with in your topic in the industry and more. Thank you.