290 MUSCLES OF THE HEAD AND NECK. 



meets its neio-hbour of the opposite side. In its upper part it is 

 placed above the concave margin of the superior constrictor. 



The circumflexiis or tensor palati arises from the navicular fossa 

 at the root of the internal pterygoid plate, from the outer side of the 

 Eustachian tube, from the spine of the sphenoid, and the edge of the 

 tympanic plate of the temporal bone. It descends perpendicularly, 

 resting on the internal pterygoid plate, between it and the internal 

 pterygoid muscle, and ends in a tendon which, turning round the 

 hamular process, where a synovial bursa) smooths its passage, extends 

 horizontally inwards, and terminates in the forepart of the aponeurosis 

 of the solt palate and the under surface of the palate bone. 



Nerves. — The muscles of this group receive their nerves from various 

 sources, some of which are not yet sufficiently detennined. The stylo-pharjni- 

 geus receives a branch from the glosso-pharyngeal ; the constrictors are supplied 

 from the same and from the pharjTigeal plexus. The tensor palati receives a 

 branch from the otic ganglion of the fifth nerve, the levator palati and azygos 

 uvulae from the facial through the petrosal nerve of the Vidian, and the palato- 

 glossus and palato-phariy-ngeus from the palatine branches of Meckel's ganglion. 



Actions. — Tlie muscles of the pharj-nx and soft palate are so arranged as to 

 accomplish, in conjunction with those of the tongue and hyoid bone, the action 

 of deglutition— that is to say, the propulsion of food into the oesophagus without 

 any jjortion being jjermitted to pass into the nasal cavity or larynx, while the 

 tongue near the fauces is thrown upwards and backwards by the stylo-glossi 

 muscles, and the larynx is drawn upwards and forwards under it by muscles 

 attached to the hyoid-bone, and by the stjdo-pharyngeus muscle, so as to be both 

 closed by the epiglottis and overlapped by the tongue, the palato-glossi muscles 

 constrict the fauces and shut off the bolus from the mouth. The soft palate is 

 raised and made tense by its superior muscles; the palato-pharyngei, being 

 approximated, nearly touch one another (the uvula lying in the small interval 

 between them), and prevent the passage of the food towards the upper part of 

 the pharynx or the posterior nares. while at the same time they form an inclined 

 surface for its guidance into the lower part of the pharynx. The food being 

 thus thrown into the grasp of the constrictors of the pharynx, those muscles 

 contract from above downwards and force it into the tube of the gullet below. 

 The Eustachian tube, according to most anatomists, is opened during degluti- 

 tion by the contraction of the levator palati and salpingo-pharjTigeus muscles. 

 It should, however, be mentioned that a different view is taken by Cleland, who 

 ] I olds — and with him, to some extent, Lusclika agrees — that the tube is closed 

 during deglutition by the thickening which takes place during the contraction 

 •of the levator i^alati, pressing up the membranous floor of the canal against 

 the firm upper and outer wall, so as comijletely to obliterate the opening. The 

 salpingo-pharyngeus. when present, assists the palato-pharjTigeus and sui:)erior 

 constrictor in elevating the pharjTix. (See Joum. of Anat., vol. iii., p. 97.) 



SUBCUTANEOUS MUSCLE OF THE NECK. 



The platysma myoides is a pale-coloured thin sheet of muscular 

 fibres, superficial to the deep cervical fascia, and extending over the 

 front and sides of the neck and lower portions of the side of the ftice. 

 Its fibres rise by thin bands from the clavicle and acromion, and from 

 the fascia covering the upper part of the deltoid, pectoral, and trapezius 

 muscles : thence they proceed upwards and inwards over the clavicle 

 and the side of the neck, gradually narrowing and approaching the 

 muscles of the opposite side. The greater number of the fibres are 

 inserted into the outer surface of the lower jaw from the symphysis to 

 the attachmeni of the masseter : the inner fibres mingle with those of 



