370 HEAD AND NECK 



the pharynx also is placed the pharyngeal plexus ot nerves, 

 which supplies its walls with motor and sensory twigs. An- 

 teriorly^ the pharyngeal wall is interrupted by the openings of 

 the nasal cavities, mouth, and larynx ; and it is from the 

 structures which lie in proximity to these apertures that it 

 derives its principal attachments. Thus from above down- 

 wards it is attached on each side (a) to the medial pterygoid 

 lamina ; (b) to the pterygo-mandibular raphe; (c) to the side 

 of the tongue ; (d) to the inner aspect of the mandible ; (e) 

 to the hyoid bone ; (/) to the thyreoid cartilage ; (g) to the 

 cricoid cartilage. Above, it is attached to the basis cranii. 

 These various attachments will be studied more fully when 

 the constituent parts of its walls are dissected. 



It should be noted that an altogether false idea of the natural form of 

 the pharynx is obtained when it is examined in its present stuffed condition, 

 and removed from the vertebral column. When seen in transverse sections 

 of the frozen body it will be noted that, with the exception of its upper or 

 nasal part, which remains patent under all conditions, the anterior wall is 

 more or less nearly approximated to the posterior wall, and below the 

 opening of the larynx it presents the appearance of a simple transverse 

 slit. 



Pharyngeal Wall. The wall of the pharynx consists of 

 four well-marked strata. These are from without inwards : 

 (i) bucco-pharyngeal fascia; (2) pharyngeal muscles; (3) 

 pharyngeal aponeurosis ; (4) mucous membrane. The 

 muscular layer, which is composed of the three constrictor 

 muscles, with the stylo-pharyngeus and pharyngo-palatinus 

 on each side, must now be dissected. 



For this purpose place the preparation so that the chin rests upon a 

 block and the pharynx hangs downwards with its posterior surface 

 towards the dissector. The constrictor muscles should now be carefully 

 cleaned, in the direction of the muscular fibres, by removing the bucco- 

 pharyngeal fascia, which covers them. 



Bucco-pharyngeal Fascia. This is a coating of fibrous 

 tissue which ensheaths both the buccinator and the pharyn- 

 geal muscles. 



Venae Pharyngese. Upon the posterior wall and lateral 

 borders of the pharynx the dissector should notice numerous 

 veins joined together in a plexiform manner. These con- 

 stitute the pharyngeal venous plexus, which collects blood 

 from the pharynx, soft palate, and prevertebral region. It 

 communicates with the pterygoid plexus and the cavernous 

 sinus. Two or more channels lead the blood from it to the 



