Carotid sheath sternum. The four major structures contained in the carotid sheath are: The carotid artery lies medial to the internal jugular vein, and the vagus nerve is situated posteriorly between the two vessels. In the upper part, the carotid sheath also contains the glossopharyngeal nerve (IX), the accessory nerve (XI), and the hypoglossal nerve (XII), which pierce the fascia of the carotid sheath. The ansa cervicalis is embedded in the anterior wall of sheath. It is formed by "descendens hypoglossi" (C1) and "descendens cervicalis" (C2-C3). The three major fascial layers in the neck contribute to the carotid sheath: the investing fascia,
Endometrial arteries the baby. The uterus, part of the female reproductive system, is composed of the myometrium and the endometrium. The myometrium is made of smooth tissue and the endometrium lines the uterus. The endometrium is important in pregnancy because it is involved in the development of the placenta and it is where the fertilized egg implants itself during pregnancy. In the endometrium there are endometrial arteries which are also known as spiral arteries. The arcuate arteries located in the myometrium, branch out into the myometrium and then spread throughout endometrium forming endometrial arteries which is how the endometrium obtains blood. Endometrial