DISSECTION OF THE ORBIT 337 



finally sinks into the upper or orbital surface of the superior 

 oblique muscle not far from its origin. 



GlandulaLacrimalis. The lacrimal gland is a small, flattened 

 and distinctly lobular structure of oval form, which is placed 

 transversely in the antero-lateral part of the orbit. It con- 

 sists of two parts or groups of lobules a superior and an 

 inferior imperfectly separated from each other. The glandula 

 lacrimalis superior, which constitutes the main mass of the gland, 

 lies in the orbital cavity. Its lateral convex surface is lodged 

 in a hollow upon the medial aspect of the zygomatic process 

 of the frontal bone, and it is bound to the lateral part of the 

 orbital arch by short fibrous bands which proceed from the 

 periosteum. The deep or medial surface is slightly concave, 

 and rests upon the levator palpebrae superioris and lateral 

 rectus, which intervene between it and the eyeball. The 

 glandula lacrimalis inferior lies below and anterior to the 

 superior part, from which it is partially separated by the ex- 

 panded tendon of the levator palpebrse superioris. It projects 

 into the base of the upper eyelid, and rests upon the con- 

 junctiva which lines the under aspect of the lid. This portion 

 of the gland has been already examined in the dissection of 

 the eyelids (p. 138). Even in the undissected subject it can 

 be seen through the conjunctiva when the upper eyelid is 

 fully everted. 



The lacrimal gland secretes the tears, and its ducts 

 (three to five from the superior part and three to nine from 

 the inferior part) open upon the under surface of the upper 

 eyelid in the neighbourhood of the fornix (Fig. 64). 



Musculus Levator Palpebra Superioris. This muscle rests 

 upon the upper surface of the rectus superior. Posteriorly, 

 it is narrow and pointed, but it expands as it passes above 

 the eyeball to reach the upper eyelid. It arises from the under 

 surface of the roof of the orbit immediately anterior to the 

 optic foramen, and in the anterior part of the orbital cavity 

 it widens out into a broad membranous expansion, the con- 

 nections of which have been described already (p. 136). The 

 lateral and medial margins of this expansion are fixed to the 

 rim of the orbital opening, in close proximity to the liga- 

 mentum palpebrale mediale and the raphe palpebralis lateralis. 

 By these attachments excessive action of the muscle upon the 

 upper eyelid is in a measure checked. 



Dissection. Divide the frontal nerve and throw the ends anteriorly and 



VOL. II 22 



