The Cervico-Facial divides up into-(1) buccal, (2) superior mandibular, and (3) inferior mandibular, all supplying muscles of expression; the latter branch supplies also the platysma muscle.

Fig. 72. - Nerves of Head and Face. 1, Sterao-cleido-mastoid; 2, Trapezius.

9. The Glosso-Pharyngeal nerve emerges from the surface of the medulla oblongata, and passes through the jugular foramen with the pneumogastric and spinal accessory nerves. It passes down between the internal carotid artery and the jugular vein, then between the internal and external carotid arteries, and passes inwards to reach the tongue. The nerve supplies the stylo-pharyngeus muscle and the mucous membrane of the tongue and pharynx.

10. The Pneumogastric or Vagus nerve emerges from the surface of the medulla oblongata, and passes through the jugular foramen with the glosso-pharyngeal and spinal accessory nerves. The nerve lies in the carotid sheath lying between the artery and the jugular vein. It then enters the thorax behind the large veins (on the right side it crosses the subclavian artery, on the left it lies between the common carotid and subclavian arteries and crosses the arch of the aorta). As the nerves cross the arteries they each give off the recurrent laryngeal branches-the one hooking round the subclavian artery, and the other round the arch of the aorta. The nerve then passes behind the root of the lung, where it breaks up into branches to form the posterior pulmonary plexus, from which it sends two branches to join with similar ones from the other nerve to form a plexus in front of the oesophagus. A branch from the left nerve then passes down in front of the oesophagus, one from the right behind the oesophagus, and terminates by supplying the stomach and other abdominal organs.

The pneumogastric nerve suppliesIn the neck - laryngeal and cardiac branches.

In the thorax - laryngeal, pulmonary, and oesophageal branches.

In the abdomen - stomach and branches to the coeliac, splenic, renal, and hepatic plexuses.

11. The Spinal Accessory nerve is formed in two parts-one in the medulla oblongata, the other from the spinal cord-the two roots unite to form one trunk, which passes through the jugular foramen with the glosso-pharyngeal and pueumogastric nerves. It passes down in the carotid sheath, and ends by supplying sterno-mastoid and trapezius.

12. The Hypoglossal nerve emerges from the surface of the medulla oblongata and passes through the anterior condyloid foramen. It then passes down the neck on the outer side of the internal carotid artery, and hooks round the occipital artery to reach the tongue, the intrinsic muscles of which it supplies.