60 DISSECTION OF THE ORBIT. 



are to be traced forwards from it : and the junction of a filament of the 

 lachrymal nerve with the former is to be sought in the bone ; the outer 

 wall of the orbit may be cut away, bit by bit, to follow the temporal 

 branch to the surface of the head. 



The ternporo-malar or orbital branch of the superior maxillary nerve 

 (fig. 2G) arises in the spheno-maxillary fossa, and divides at the back of 

 the orbit into malar and temporal branches, which ramify in the face and 

 the side of the head with companion vessels. 



The malar branch (r. subcutaneus malse) is directed forwards through 

 a foramen in the malar bone: after emerging from its foramen, this 

 branch supplies the orbicularis, and communicates with the facial nerve, 

 (p. 48). 



The temporal branch ascends in a groove in the bone on the outer wall 

 of the orbit ; and being joined by a filament from the lachrymal nerve, 

 passes into the temporal fossa through a foramen in the malar bone : it is 

 then directed upwards between the temporal muscle and the skull, and 

 perforates the temporal fascia near the orbit (p. 23). 



Orbitalis muscle. At the lower and outer angle of the orbit a thin fleshy 

 layer is sometimes well seen. The fibres cross the spheno-maxillary fis- 

 sure, being attached to the edges, and are pierced by the malar branch of 

 the temporo-malar nerve. 



LACHRYMAL APPARATUS (fig. 13). The lachrymal glands, punota, 

 canals, and sac, constitute the apparatus by which the tears are formed, 

 and conveyed to the nose. The gland has been already described (p. 51 ). 



Dissection. A bristle should be introduced into each lachrymal canal 

 through the punctum of the eyelid. The lachrymal sac will appear by 

 removing the tensor tarsi and the areolar tissue from its surface, as it lies 

 on the os unguis. The prolongation from the ligamentum palpebrarum 

 over the sac should be defined. 



The puncta lachrymalia (*) are two small apertures, one for each lid, 

 by which the lachrymal canals receive the tears. Each is situate in the 

 free margin of the lid, about a quarter of an inch from the inner canthus, 

 and in the elevation of the papilla lachrymalis. 



Fig. 13. 



1. Puncta lachrymalia. 



3. Upper, and 3, Lower lachrymal canal. 



4. Caruncula lachrymalis. 

 fl. Lachrymal sac. 



6. Lachrymal duct. 



THE EYELIDS AND LACHRYMAI, APPARATUS. 



The lachrymal canals (fig. 13, 2 ftnd s ) lead from the puncta, and convey 

 the tears to the lachrymal sac; their situation is marked by the bristle- 

 inserted in them. In their course inwards the canals lie along the liga- 

 mentum palpebrarum, one ( 2 ) above and the other ( 3 ) below it, and they 

 are somewhat arched with the concavity towards each other. Internally 

 they open near together into thu lachrymal sac rather above its middle. 



