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,
Carotid body body is sent to the cardiorespiratory centers in the medulla oblongata via the afferent branches of the glossopharyngeal nerve. The afferent fibres of the aortic body chemoreceptors are relayed by the vagus nerve. These centers, in turn, regulate breathing and blood pressure, with hypoxia causing an increase in ventilation. A paraganglioma is a tumor that may involve the carotid body and is usually benign. Rarely, a malignant neuroblastoma may originate from the carotid body. Innervated by glossopharyngeal nerve (cranial nerve IX). Carotid body The carotid body ("carotid glomus" or "glomus caroticum") is a small cluster of chemoreceptors and supporting cells