X PC anatomy: origin, main trunk and distal branches Where to look for the lesion?

X PC (VAGUS NERVE): functions MIXED NERVE: parasympathetic nerve supplying regions of head and neck and thoracic and abdominal viscera. Additional components : Taste from epiglottis. Sensory nerve to external ear. Visceral sensation from thoracic and abdominal viscera. Motor: soft palate, pharyngeal and laryngeal muscles.

X PC: segments INTRAAXIAL. CISTERNAL. SKULL BASE. EXTRACRANEAL. EXTRACRANEALES BRANCHES IN HEAD AND NECK.

A) INTRACRANEAL SEGMENTS INTRAAXIAL: Nucleus ambiguus, solitary tract nucleus, dorsal vagal nucleus in upper and middle medulla. They exit at postolivary sulcus. CISTERNAL: Travels anterolaterally between the IX and XI nerves. SKULL BASE: Posterior pars vascularis of jugular foramen( JF).

Axial diagram through the medulla with principal nuclei associated with vagus nerve function. Cisternal portion of low cranial nerves (IX-XI) and skull base entrance is also shown. Imaging Anatomy. Hansberger

Cisternal segment. Anatomic correlation

Posterior fossa T 2* axial plane

B) EXTRACRANEAL SEGMENTS o EXTRACRANIAL - Exits from JF to the nasopharyngeal carotid space. - Descends along posterolateral aspect of the internal carotid artery (ICA) into the thorax. -Anterior to aortic arch with the left and subclavian artery on the right. -Plexus around the esophagus and major blood vessels to the heart and lungs and finally in abdomen to viscera and GI tract. o EXTRACRANEAL BRANCHES TO HEAD AND NECK: auricular, pharyngeal, superior and inferior laryngeal nerves or recurrent nerves (RN).

Diagram shows X CN ( triangles) and RN (arrows) gross anatomy in cervical and thoracic segments. Consecutive axial diagrams corresponding to anterior figure levels. Glazer et al;Extralaryngeal causes of vocal cord paralysis CT.

Axial diagram of the nasopharyngeal carotid spaces shows X CN posterior to the ICA and jugular vein with IX and XI CN. Imaging Anatomy. Hansberger

Axial diagram through the infrahyoid neck at the level of the thyroid gland demonstrates vagus trunk as the only remaining CN in carotid space and RN in the tracheoesophageal groove. Imaging Anatomy. Hansberger

Anatomical correlation

Vagus trunk: anatomical correlation Left vagus trunk (star) in the posterolateral aspect of ICA

Right recurrent The tight vagus nerve (star) descends posterior to the ICA. It reflexes under the subclavian artery and ascends as the recurrent (curved arrow) posteriorly back to larynx. Cervical plexus Larynx RBCVRBCA RSCA RBCV right brachiocephalic vein RBCA right brachiocephalic artery RSCA right subclavian artery

Vagus trunk (arrow) and left recurrent (curved arrow)‏

Left recurrent Vagus trajectory anterior to the aortic arch, left recurrent nerve exit (arrows). Posterior trajectory in aortopulmonary window and ascent parallel to the trachea. aortaaorta pulmonary artery aorta LBCV RSCA thyroid RSCA right subclavian artery LBCV left brachiocephalic vein