PREPAKATION OF PHARYNX. 123 



sympathetic nerves, are to be cut near the first rib, and all are to be sepa- 

 rated from the spine as high as the basilar process of the occipital bone ; 

 and without injuring, on the left side, the vessels and nerves near the 

 skull. 



For the division of the skull turn upwards the inner surface of the base, 

 and make the following incisions in the posterior fossa. On the right side 

 a cut, with the chisel, is to be carried along the line of union of the 

 petrous part of the temporal with the occipital bone. On the left side an- 

 other cut with the chisel is to be made in the same direction, but through 

 the occipital bone internal to the foramen jugulare and the inferior petrosal 

 sinus : this is to begin rather behind that foramen, and to end opposite the 

 one on the other side. The skull is to be sawn through vertically on the 

 left side close behind the mastoid part of the temporal bone, so that the 

 incision shall meet the outer end of the cut made with the chisel. 



Finally placing the skull again upside down, let the student chisel 

 through the basilar process of the occipital bone between the attachments 

 of the pharynx and the muscles of the spinal column, the instrument being 

 directed backwards. The base of the skull is now divided into two parts 

 (one having the pharynx attached to it, the other articulating with the 

 spine), which can be readily separated with a scalpel. 



The spinal column with the piece of the occipital bone connected with 

 it should be set aside, and kept for after examination. 



Dissection of the pharynx (fig. 28). Let the student take the anterior 

 part of the divided skull, and, after moderately filling the pharynx with 

 tow, fasten it with hooks on a block, so that the oesophagus may be pen- 

 dent and towards him. 



On the left side of the pharynx a different view from that of the right 

 side may be obtained of the cranial and sympathetic nerves near the skull 

 (p. 112), when some loose areolar tissue, and the styloid process with its 

 muscles, have been removed : if the lower ends of the nerves are fixed 

 with pieces of thread, a more satisfactory examination can be made of 

 them. 



Afterwards the dissector may proceed to remove the fascia from the 

 constrictor muscles of the right side (fig. 28), in the direction of the fibres 

 these radiating from the side to the middle line. The margins of the 

 two lower constrictor muscles (middle and inferior) are to be defined. 

 Beneath the lower one near the larynx, will be found the recurrent nerve 

 with vessels ; whilst intervening between the middle and superior, are the 

 stylo-pharyngeus muscle and the glosso-pharyngeal nerve. 



To see the attachment of the superior constrictor to the lower jaw and 

 the pterygo-maxillary ligament, it will be necessary to cut through the in- 

 ternal pterygoid muscle of the right side. Above the upper fibres of this 

 constrictor, and near the base of the skull, are two small muscles of the 

 palate (F and H) entering the pharynx : one tensor palati, lies between 

 the internal pterygoid plate and muscle ; and the other levator palati, is 

 farther in, and larger. 



The PHARYNX is situated behind the nose, mouth, and larynx. Its 

 extent is from the base of the skull to the cricoid cartilage of the larynx, 

 whore it ends in the oesophagus. In form it is somewhat conical, with the 

 dilated part upwards ; and in length it measures from five to six inches. 



Tlit! tube of the pharynx is incomplete TnTPPont, where it communicates 

 with the cavities above mentioned, but is quite closed behind. On each 

 side of it are placed the trunks of the carotid arteries, with the internal 



