Fig. 53- Horizontal Section through the Head at the level of the Axis. 



One of a series of frozen sections through the head. 



The Vestibule of the Mouth and the Buccal Cavity have only been cut at their 

 lowest points, where the tongue is adherent to the floor of the mouth. Of the 3 saiivarv 

 glands (Sublingual, Submaxillary and Parotid) the last is of interest because it extends far 

 inwards, and, on the left side of the figure, even forwards under cover of the lower jaw. 

 The tip of the Uvula was cut by this section. 



The Tonsil is divided below its middle : it lies in a capsule which is closelv 

 connected with the muscles of the Pharynx. Very important are the parts around the 

 tonsil, in deciding the question of the source of furious haemorrhage in some cases of 

 tonsillotonn- ? We mentioned that the Tonsillar Branch of the Ascending Palatine Artery- 

 is far too small to cause serious haemoirhage. Of the large vessels, the Internal Carotid 

 which is said to have been wounded during the operation, lies ^5 inch away from the 

 tonsil. It could only be injured when a particular!}- clumsy surgeon cuts \ery deeph'. 

 This statement also holds good for the External Carotid. It is the Facial Arter}- which 

 lies \ery near the tonsil and may be injured (Merkel). This vessel arises from the Ex- 

 ternal Carotid at the level of the lower end of the tonsil, passes between the muscles 

 coming from the Styloid Process, describes an S-shaped cur\'e and runs along the circum- 

 ference of the tonsil. Serious haemorrhage may also be clue t'.i injurv of the Pharyngeal 

 Venous Plexus. 



Externally and behind the Tonsil the following structures are in close relation : 

 Internal Carotid Artery, Internal Jugular Vein, 9th, loth, nth. Crania! Nerves and Hypo- 

 glossal Nerve, all lying in one sheath which is attached above to the fibro-cartilage of the 

 posterior lacerated foramen. 



The Vertebral Artery having arisen from the Subcla\ian runs upwards, passing 

 through the foramen in the transverse processes of the upper 6 Cervical Vertebrae. Then 

 curving horizontally backwards — this part of its course is shewn on the left side of our 

 figure — it comes to lie under the Dura Mater which it pierces. (Cf. Fig. 15.) Il now 

 lies in the cranial cavity on the side of the bulb, and after running inwards it joins with 

 its fellow to form the Basilar Artery. 



General Remarks on the jugular \' e i n s. 



A large share of the venous blood is carried from the Head and the Neck to 

 the Heart by Veins which have a separate course and do not correspond exactly to any 

 artery. These veins are termed Jugular Veins. To the Internal Carotid corresponds 

 more or less the Internal Jugular; to the External Carotid, the External Jugular, formed 

 by the union of Temporal and Facial Veins. The Facial Vein ma}' also be continued 

 downwards as the Anterior Jugular Vein. There may further be a Posterior Jugular Vein 

 (cf. Fig. 6") at the anterior border of the Trapezius Muscle. 



The relation of these veins to the Sterno-Cleido-Mastoid is as follows: the Ex- 

 ternal Jugular crosses the outer surface of the muscle which, with its inner surface, covers 

 the Internal. Along the Anterior border runs the Anterior Jugular. The Posterior Jugular 

 is the least constant of these vessels. 



All these veins end under cover of the Sternomastoid, where the large L3'mphatic 

 Channels open into the Venous System. The Anterior Jugular Veins comnnmicate just 

 above the clavicle bv a transverse anastomotic branch. 



