306 HEAD AND NECK 



(O.T. organ of Jacob son), a tubular structure which is highly developed in 

 some of the lower animals. 



Construction of the Nasal Septum. Strip the muco- 

 periosteum from the exposed surface of the septum nasi, and 

 the parts forming the septum will be rendered visible. The 

 bulk of the partition is composed of the vomer and the per- 

 pendicular lamina of the ethmoid posteriorly, and of the 

 septal cartilage anteriorly. Small portions of other bones take 

 a minor part in its construction. Thus, above and posteriorly 

 there are the crest and rostrum of the sphenoid ; above and 

 anteriorly are the nasal spine of the frontal bone and the crest 

 of the nasal bones ; whilst below there is the crest of bone 

 formed by the apposition of the palatal processes of the 

 palate and maxillary bones of opposite sides. 



Cartilago Septi Nasi. The septal cartilage fills up the 

 wide angular gap which intervenes between the vomer and the 

 perpendicular lamina of the ethmoid, and it projects forwards 

 towards the point of the nose. It is a broad irregularly 

 quadrilateral plate. Its upper and posterior border is in ap- 

 position with the anterior border of the perpendicular lamina 

 of the ethmoid ; its lower and posterior border, much thickened, 

 is received into the groove in the anterior border of the vomer 

 and the nasal crest of the maxillae. The angle between the 

 two borders mentioned is prolonged backwards, for a varying 

 distance, in the form of a tongue-shaped cartilaginous process, 

 which occupies the interval between the two plates of the 

 vomer. The upper and anterior border of the septal cartilage 

 is in contact, above, with the suture between the two nasal 

 bones ; below that, it is related to the two lateral cartilages 

 of the nose, whilst still lower down it occupies the interval 

 between the medial parts of the two larger alar cartilages. 



Its connection with the lateral cartilage on each side is a very intimate 

 one ; indeed, below the nasal bones, the three cartilages are directly 

 continuous, but lower down they are separated by a fissure which runs 

 upwards for some distance on each side. The lower and anterior border is 

 very short ; it is free, and extends backwards to the anterior nasal spine. 

 The anterior angle of the septal cartilage is blunt and rounded, and does not 

 reach to the point of the nose, which is formed by the alar cartilages. 



The deviation of the septum nasi from the median plane will now (in all 

 probability) be seen to be due to a bulging of the vomer and perpendicular 

 lamina of the ethmoid to one side, along their line of union. It is not 

 developed until after the seventh year. 



Dissection. The septal cartilage and thin bony part of the 

 septum must now be removed piecemeal. The removal must 



