GREAT VESSELS AND NERVES OF NECK 303 



branch, which perforates the temporal fascia and anastomoses 

 in the temporal fossa with the deep temporal branches of the 

 internal maxillary. The course of this branch and also the 

 distribution of the terminal branches have been followed in 

 earlier stages of the dissection (pp. 266, 267). 



Dissection. Divide the posterior belly of the digastric immediately 

 below its origin, and turn it downwards and anteriorly towards the hyoid 

 bone ; then examine the stylo-pharyngeus muscle. It may be necessary to 

 cut the occipital and posterior auricular arteries in order to gain free access 

 to the deeper parts, but this should not be done unless it is necessary. 

 Care must be taken whilst cleaning the stylo-pharyngeus to avoid injuring 

 the glosso-pharyngeal nerve, which turns round its posterior border and 

 crosses its superficial surface. 



Musculus Stylopharyngeus. This is the longest of the 

 three slender muscles which spring from the styloid process. 

 It arises from its deep or medial surface close to its root, and 

 extends downwards and anteriorly to gain the side of the 

 pharynx, where it disappears under cover of the upper border 

 of the middle constrictor muscle. Whilst under cover of 

 the middle constrictor its fibres blend with those of the palato- 

 pharyngeus, and, with these, are inserted into the posterior 

 border of the corresponding lamina of the thyreoid cartilage. 

 Some of the fibres, however, are lost in the wall of the pharynx. 

 If the dissector removes the fascia at the posterior part of 

 the thyreo-hyoid space he will expose the lower fibres of the 

 middle and the upper fibres of the inferior constrictor, and 

 in the interval between them, on a deeper plane, the lateral 

 surface of the lower part of the stylo-pharyngeus. 



Dissection. Snip through the base of the styloid process with the bone 

 forceps, and throw it and the attached muscles downwards and anteriorly. 

 The upper parts of the internal carotid artery and the internal jugular vein 

 are now exposed, and the ascending pharyngeal artery can be followed to 

 the base of the skull. 



Arteria Pharyngea Ascendens. To expose this vessel the 

 dissector must push the external carotid anteriorly and clean 

 the interval between it and the internal carotid. The 

 ascending pharyngeal springs from the medial surface of the 

 external carotid close to its lower end and is its smallest 

 branch. It ascends along the lateral border of the pharynx, 

 lying between the stylo-pharyngeus laterally and the con- 

 strictors of the pharynx medially, first in a plane between the 

 external and internal carotid arteries, and then to the medial 

 side of the internal carotid. As it passes upwards it gives 



