DISSECTION OF THE HEAD AND NECK. 205 



edge of the great comu, and the pharyngeal artery passing beneath 

 it. 



The Palato-pharyngeus has already been in part dissected with the 

 muscles of the soft palate. See page 203. 



The Pterygo-pharyngeus. This muscle arises from the pterygoid pro- 

 cess, from which point its fibres diverge to the upper and lateral aspect 

 of the forepart of the pharynx. At its lower edge its fibres are parallel 

 to, and with difficulty separated from, those of the palato-pharyngeus. 

 Its outer surface is constantly covered by a layer of fatty elastic tissue. 



The Hyo-pharyngeus, migin — thjToid or heel process of the hyoid 

 bone. 



The Thyro-pharyngeus, m'igin — thyroid cartilage. 



The Crico-pharyngeus, origin — cricoid cartilage. 



These three muscles succeed one another in the order named, the first- 

 mentioned being the most anterior. They pass upwards over the side of 

 the pharynx, and terminate on the middle line of its roof. 



The Stylo-pharyngeus. This is a thin, strap -like muscle arising 

 from the inner surface of the great cornvi of the hyoid bone near its 

 upper extremity. It descends to the pharynx, and expands on it at the 

 outer edge of the pterygo-pharyngeus. 



The Small Stylo-pharyngeus. This muscle is not constant, though 

 freqviently present. It is a delicate, worm-like muscle arising from the 

 inner surface of the great comu, about an inch above its lower extremity. 

 It passes upwards on the pharynx at the anterior edge of the hyo- 

 pharyngeus. 



The Aryteno-pharyngeus. This muscle will not be seen at present. 

 It is a small slip arising from the arytenoid cartilage, and passing to the 

 pharynx at its junction with the oesophagus. 



Action of the Pharyngeal Muscles. — The stylo-pharyngeus dilates the 

 anterior part of the pharynx for the reception of the bolus. All the 

 other muscles are constrictors, grasping in succession the bolus, and 

 carrying it on to the oesophagus. 



The Cerato-hyoid {Hyoideus jmrvus of Percivall) (Plate 33). This, 

 muscle is most conveniently dissected at this stage, and it is therefore 

 here described although not belonging to the pharynx. It is a 

 small flat muscle occupying the angle between the small and the thyroid 

 cornu of the hyoid bone. It arises from the posterior edge of the 

 small cornu, and from the great cornu immediately above the inter- 

 comual articulation. It is inserted into the upper edge of the thyroid 

 cornu. The lingual artery, in crossing down to the base of the tongue, 

 passes over the muscle. 



Action. — To elevate the thyroid cornu and with it the larynx. 



The Pharyngeal Artery. This is a small branch of the submaxillary 

 which passes beneath the great cornu, crossing either outwardly or 



