340 



MUSCLES AND FASCI-E. 



tongue back into the mouth. The whole length of these two muscles acting 

 along the middle line of the tongue will draw it downwards, so as to make it 

 concave from side to side, forming a channel along which fluids may pass 

 towards the pharynx, as in sucking. The Hyo-glossi muscles draw down the 

 sides of the tongue, so as to render it convex from side to side. The Linguales, 

 by drawing downwards the centre and apex of the tongue, render it convex 

 from before backwards. The Palato-glossi draw the base of the tongue up- 

 wards, and the Stylo-glossi upwards and backwards. 



5. PHAKYNGEAL REGION. 



Constrictor Inferior. Constrictor Superior. 



Constrictor Medius. Stylo-pharyngeus. 



Palato-pharyngeus. 



Dissection (Fig. 223). In order to examine the muscles of the pharynx, cut through the 

 trachea and oesophagus just above the sternum, and draw them upwards by dividing the loose 



areolar tissue connecting the pharynx with the 



Fig. 223. Muscles of the Pharynx. External front of the vertebral column. The parts being 

 View. drawn well forwards, apply the edge of the saw 



immediately behind the styloid processes, and 

 saw the base of the skull through from below 

 upwards. The pharynx and mouth should then 

 be stuffed with tow, in order to distend its 

 cavity and render the muscles tense and easier 

 of dissection. 



The Inferior Constrictor, the most 

 superficial and thickest of the three 

 constrictors, arises from the side of the 

 cricoid and thyroid cartilages. To the 

 cricoid cartilage it is attached in the 

 interval between the crico-thyroid 

 muscle, in front, and the articular facet 

 for the thyroid cartilage behind. To 

 the thyroid cartilage, it is attached to 

 the oblique line on the side of the 

 great ala, the cartilaginous surface be- 

 hind it, nearly as far as its posterior 

 border, and to the inferior cornu. 

 From these attachments, the fibres 

 spread backwards and inwards, to be 

 inserted into the fibrous raphe in the 

 posterior median line of the pharynx. 

 The inferior fibres are horizontal, and 

 continuous with the fibres of the oeso- 

 phagus ; the rest ascend, increasing in 

 obliquity, and overlap the Middle Con- 

 strictor. The superior laryngeal nerve 

 passes near the upper border, and the inferior, or recurrent laryngeal, beneath 

 the lower border of this muscle, previous to their entering the larynx. 



Relations. It is covered by a dense cellular membrane which surrounds the 

 entire pharynx. Behind, it is in relation with the vertebral column and the 

 Lougus Colli muscle ; laterally, with the thyroid gland, the common carotid 

 artery, and the Sterno-thyroid muscle ; by its internal surface, with the Middle 

 Constrictor, the Stylo-pharyugeus, Palato-pharyngeus, and the mucous mem- 

 brane of the pharynx. 



The Middle Constrictor is a flattened, fan-shaped muscle, smaller than the pre- 

 ceding, and situated on a plane anterior to it. It arises from the whole length 



