3 io HEAD AND NECK 



Lateral Wall of the Nasal Cavity. The lateral wall of 

 each nasal cavity is rendered uneven by the projection of 

 the three conchae (O.T. turbinal bones). 



The part which the different bones take in the formation of the lateral 

 wall of the cavity of the nose must in the first place be studied in a 

 sagittal section through the macerated skull, and the dissector should 

 constantly refer to such a preparation during the dissection. Anteriorly, it 

 is formed by the lateral cartilage, the alar cartilage, the nasal bone, and the 

 frontal process of the maxilla. More posteriorly the lacrimal, the ethmoid, 

 and the inferior concha, and a portion of the body of the maxilla, 

 enter into its construction ; whilst still more posteriorly are the perpen- 

 dicular part of the palate bone and the medial pterygoid lamina of the 

 sphenoid. Placed in relation to the lateral aspect of the lateral wall are 

 the ethmoidal air-cells, which intervene between the upper part of the 

 nasal cavity and the orbit, whilst, at a lower level, the great air sinus 

 of the maxilla, the maxillary sinus, is situated immediately to the lateral 

 side of the nasal cavity (Fig. 115). 



Turning now to the dissection, the dissector will see that 

 the lateral wall is separable into three areas or districts. 

 They are (i) the vestibule; (2) the atrium meatus medii ; 

 (3) the region of the conchse and the intervening meatuses. 



Vestibulum Nasi. The vestibular part (Fig. 116, e, e') 

 of the lateral wall is a depression of a somewhat oval form 

 placed immediately above the aperture of the nostril. It is 

 partially divided into an upper and lower portion by a short 

 ridge, which projects forwards from its posterior boundary ; 

 and in the whole of its extent it is clothed by ordinary integu- 

 ment. From the skin a number of stout, stiff hairs, termed 

 vibrisscz, project (Fig. 1 1 6, 5 ). The vibrissae which spring 

 from the anterior part of the region incline backwards, whilst 

 those which are implanted into the posterior part are directed 

 forwards ; in that manner a sieve-like arrangement is provided 

 at the anterior aperture of the nose. The vestibular part of 

 the lateral wall is placed opposite the corresponding area on 

 the septum nasi, and the two together constitute an ampullated 

 entrance to the nasal cavity. The capacity and shape of the 

 vestibule are influenced to a certain extent by the contraction 

 of the nasal muscles. 



Atrium Meatus Medii. The atrium of the middle meatus 

 of the nasal cavity (Fig. 116, s) is placed above, and slightly 

 posterior to, the vestibular district, and it receives its name from 

 the fact that it lies immediately anterior to the middle meatus. 

 It is slightly hollowed out and concave, and at its upper part, 

 near the nasal bone, a feeble elevation termed the agger nasi 



