734 



NOSE. 



of the facial artery, for they are usually larger 

 than the angular artery, which is given off as a 

 branch from one of them. They chiefly supply 

 the skin and muscles; they form a complete 

 network over the nose, and those of one side 

 anastomose freely in the middle line with those 

 of the other. Many of their branches also 

 pass between the cartilages or turn in at the 

 nostrils and supply the anterior part of the 

 mucous membrane. 



The veins of the nose, so far as they are 

 known, are associated with its arteries. Their 

 communication with the veins within the skull 

 has been already mentioned. The anastomosis 

 is chiefly effected by means of the branches of 

 the ethmoidal and spheno-palatine veins, which 

 communicate with branches opening into the 

 longitudinal and coronary sinuses. 



The lymphatic vessels of the nose have not 

 been particularly examined. Cloquet says 

 their principal trunks accompany the blood- 

 vessels and go to the jugular ganglia. 



Developement of the nose. The develope- 

 ment of the nasal cavities lays, as it were, the 

 foundation for the construction of the face.* 

 They are first formed as a kind of canal, whose 

 lateral walls are chiefly composed by the ante- 

 rior and lateral frontal processes of Reichert 

 those processes which grow out from the sides 

 of the covering of the first cerebral vesicle 

 ( Stirnkappe), in front of the first visceral arch. 

 This canal has on its outer side and behind it 

 the rudimental substance for the upper jaws, 

 (the superior maxillary processes of Reichert,) 

 and above it the base of the skull and the 

 origins of the first pair of visceral arches thence 

 arising. As the upper jaws grow with a rapi- 

 dity far exceeding that of the growth of the 

 frontal processes, they come at last to form 

 alone the lateral walls of this canal, while the 

 frontal processes form its inner walls ; and, 

 together with those changes, the canal becomes 

 deeper, and its external apertures, which at 

 first lay at the sides of the head between the 

 two ftontal processes of each side, approach 

 the median line, and assume a lower position. 

 After this, as the upper jaw of each side, con- 

 tinuing to grow inwards, approaches that of 

 the opposite side, they at length unite to form 

 the palate, and thus separate the common ca- 

 vity, which at first existed, into an oral and a 

 nasal cavity. 



Of the parts just mentioned, the anterior 

 frontal process is regarded by Reichert as the 

 basis in which the nasal bone is developed ; 

 and the lateral frontal, or naso-frontal process 

 as the basis for the lachrymal bone. The supe- 

 rior maxillary bone appears to be developed in 

 the part named after it; the intermaxillary bone 

 in a portion of the anterior frontal process, or 

 its junction with the superior maxillary pro- 

 cess; the palate bone and the pterygoid pro- 

 cesses in the upper pait of the first visceral 

 arch. 



The formation of the parts within the nasal 

 cavities is, he says, thus effected : within the 



* Reichert, Ueber die Visceral-bogen, Miiller's 

 Archiv. 1837, pp. 144 and 159. This account is 

 drawn from the developement of the Pig. 



formative substance enclosed between the walls 

 of the one rudimental cavity two cartilages 

 form ; one of these is the prolonged cartila- 

 ginous body of the first cephalic vertebra which 

 forms the septum of the nasal cavities, and may 

 be traced without any breach of continuity to 

 their outer orifice, where it ends membranous 

 in the adjacent formative mass. The other 

 cartilage is double, and appears somewhat 

 later than the preceding, on each side of which 

 it lies close to the lower part of the first ce- 

 phalic vertebra, with an arched surface directed 

 outwards to the eye. Each of these second, or 

 lateral cartilages becomes the cellular portion 

 of the ethmoid bone, the lamina papyrucea, 

 and may be easily separated from the vertebra 

 and its visceral arch, from which its formation 

 is entirely distinct. Even for some time after 

 they are ossified this separation may be effected 

 without injury to the surrounding parts ; but at 

 a later period they completely coalesce. The 

 ossification of the septum takes place later than 

 that of the other bones of the face. In all 

 Mammalia it makes progress from the base of 

 the skull downwards and forwards, and in all a 

 part of the septum in front and below is left 

 unossified ; so that divisions are produced 

 which had originally no existence. The vomer, 

 Reichert thinks, is formed separately when the 

 palatine portions of the superior maxillary 

 bones meet together. 



The olfactory nerve is originally, like the 

 optic and auditory nerves, a kind of vesicular 

 or tubular prolongation from the medullary 

 tube which constitutes the cerebro-spinal axis 

 of the embryo. According to Valentin,* it 

 proceeds from the most anterior part of this 

 tube, that is, from the foremost of the three 

 embryonic cerebral vesicles; but, according to 

 Reichert, from the lower and front part of the 

 side of the second of them. Von Baerf found 

 the olfactory nerves presenting this vesicular 

 form in the chick during the third day of in- 

 cubation; they projected from the lower surface 

 of each hemisphere into the formative tissue 

 of the skull, and exhibited a small round pel- 

 lucid surface bordered by a dark circle. Rathke 

 observed similar appearances in the sheep and 

 adder. The interior of the vesicle is lined, 

 according to Valentin, by a delicate ciliary 

 epithelium. Anteriorly it appears to terminate 

 at the end of the olfactory bulb ; posteriorly it 

 is continuous with the anterior part of the 

 lateral ventricles of the cerebrum. 



The early developement of the human nose 

 has not been particularly studied, but is pro- 

 bably very similar to that just described from 

 observations in the lower animals. In a well- 

 formed embryo an inch in length, I have found 

 the nasal cavities of proportionally large size. 

 On their lateral walls they present distinct traces 

 of the rudiments of the two lower turbinated 

 bones in prominent horizontal folds of the lining- 

 membrane. The palate is at this time formed 

 only anteriorly and at its sides ; its middle por- 

 tion is widely open, exposing to the view from 



* Soemmering, 1. c. p. 404. 

 t Quoted in Bisclioff, Entwickelungsgeschichte 

 (Soemmering, Vom Baue, &c. B. viii.) 



