Chap. iv. j THE ORBIT AND EYE. 39 



In paralysis of the sixth nerve there is con- 

 vergent strabismus, with consequent diplopia, and an 

 inability to rotate the eye directly outwards. 



In paralysis of the first division of the fifth 



there is a loss of sensation in all the conjunctiva, except 

 such as covers the lower lid (supplied by the palpebral 

 branch of the infraorbital nerve), loss of sensation in 

 the globe, and in the skin supplied by the supratrochlear 

 and supraorbital nerves, and in the mucous and cuta- 

 neous surfaces supplied by the nasal nerve. No reflex 

 movements (winking) follow upon irritation of the 

 conj unctiva, although the patient can be made to wink 

 on exposing the eye to a strong light, the optic nerve 

 in this case transmitting the impression to the facial 

 nerve. Sneezing also cannot be excited by irritating 

 the mucous membrane in the anterior part of the nose. 

 Destructive ulceration of the cornea may follow this 

 paralysis, due partly to damage to the trophic branches 

 contained in the paralysed nerve, partly to the anaes- 

 thesia which renders the part readily injured, and 

 partly to the loss of the reflex effect of the sensory 

 nerves upon the calibre of the blood-vessels, whereby 

 the inflammation is permitted to go uncontrolled 

 (Nefctleship). 



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 



