THE MOUTH 



1349 



conjunctivae, into which the numerous ducts open, and it may be seen through the 

 conjunctiva on everting and raising the upper lid. 



The position of the lacrimal puncta should be noted; owing to their backward direction, 

 the lids must be previously everted. The puncta are kept open by a minute fibrous ring. 



Each is situated on a minute papilla at the junction of the medial and straight third of 

 the lid with the lateral curved two-thirds. Close to the medial angle, in addition to the puncta 

 and papillae, should be noted the caruncula lacrimalis, with its delicate hairs, and the phca 

 semilunaris, which corresponds to the third eyelid of certain birds. 



The lacrimal sac is a most important part of the lacrimal apparatus, from its 

 disfiguring diseases; it lies in a bony groove, between the nasal process of the 

 maxilla and the lacrimal bone. The medial palpebral ligament crosses it a little 

 above its centre (fig. 1095). Thus two-thirds of the sac are below the hgament, 

 and in suppuration the opening is made below it also. The angular artery ascends 

 on the nasal side of the sac. 



The manipulation of a probe along the lacrimal passages should thus be practised: — the 

 lower lid being drawn laterally and downward by the thumb, the probe is passed vertically into 

 the punctum, then turned horizontally and passed on till it reaches the medial wall of the sac. 

 It is then rotated somewhat forward, raised vertically, and pushed gently along the duct down- 

 ward, and a little lateralward and backward, till the floor of the nose is reached, the operator 

 aiming, as it were, for the site of the first molar tooth. The naso-lacrimal duct extends from 

 the lower end of the lacrimal sac to the inferior meatus of the nose and is about 1 . 2 cm (| in.) 

 in length. 



If the eyes are opened naturally, the greatest part of the cornea, behind it the iris, with the 

 pupil in the centre, on either side of the cornea some of the sclerotic, the semilunar fold, and 

 caruncle can be seen. 



THE MOUTH 



The lips. — When the whole thickness of the lip is incised the labial artery 

 will be found lying near the free margin, internal to the orbicularis muscle, and 



Fig. 1096. — Side of the Face \nd Mouth Cavity, showing the Three Salivary Glansd. 



Accessory parotl 



Duct of accessory 

 parotid 



Duct of parotid 



Bristle inserted 

 into duct 



Frenulum linguae. 



Major sublingual, 

 duct 



Sublingual gland 



Duct of submaxil 

 lary gland 



Mylo-hyoid muscle 



Anterior belly 

 ^ digastric muscle 



Parotid gland 



Masseter muscle 



Sterno-mastoid 

 muscle 



Posterior belly of 

 digastric muscle 



Lingual nerve 



Submaxillary 

 gland, 

 drawn backward 



Loop of fascia 



Hyoid bone 



Deep portion of submaxillary gland 



between it and the mucosa. There is a very free anastomosis between the 

 arteries of the opposite sides. 



If the tongue be raised, the under surface is seen to be smooth and devoid of 

 papillse. In the middle line is the frenulum. When division of this is really 

 required in tongue-tie, the scissors should be kept close to the bone, in order to 

 avoid the ranine vessels. 



