48 SURGICAL APPLIED ANATOMY. [Chap. iv. 



nerves upon the calibre of the blood-vessels, whereby 

 the inflammation is permitted to go uncontrolled 

 (Nettleship). 



In paralysis of the cervical sympathetic 



there is narrowing of the palpebral fissure from 

 some drooping of the upper lid, apparent recession 

 of the globe within the orbit, and some narrow- 

 ing of the pupil from paralysis of the dilator 

 muscle of the iris, which muscle is supplied by the 

 sympathetic. The drooping of the upper lid may be 

 explained by the fact that each eyelid contains a layer 

 of unstriated muscle fibre. That in the upper lid arises 

 from the under surface of the levator palpebrse, and 

 is attached to the tarsal cartilage near its upper mar- 

 gin (Fig. 11). This layer of muscle, which, when in 

 action', would keep up the lid, is under the influence of 

 the cervical sympathetic. The recession of the globe 

 is supposed by some to be due to paralysis of the 

 orbitalis muscle of H. Miiller. This muscle bridges 

 over the spheno-maxillary fissure, is composed of 

 unstriated fibres, and is innervated by the sympathetic. 

 Contraction of the muscle (as produced by irritation 

 of the cervical sympathetic in animals) causes pro- 

 trusion of the globe, while section of the sympathetic 

 in the neck produces retraction of the eye-ball (01. 

 Bernard). No changes are observed in the calibre 

 of the blood-vessels of the globe. 



The globe; the cornea. The thickness of the 

 cornea varies from 9 mm. in the central parts to 1 ! mm. 

 at the periphery. One is apt to be a little deceived as 

 to its thickness, and on introducing a knife into the 

 cornea, the instrument, if not entered at the proper 

 angle, may be thrust for some little distance among 

 the laminae of the part. In front the cornea is covered 

 by stratified epithelium. When this layer has been 

 removed by abrasion, a white deposit of lead salts may 

 take place in the exposed cornea! tissue in cases where 



