FRONTAL AND ORBITAL REGION. 1*7 



the inner angle of the frontal bone, the nasal process of the 

 superior maxillary, and the tendon of the tarsal cartilages ; 

 encircling the orbit, it is inserted into the same point from 

 which it arose, thus making a sphincter muscle. At the 

 inner angle of the orbit certain ascending fibres of the 

 orbicularis, springing from the tendon of the tarsal carti- 

 lages, expand fan-shaped, are inserted into the inner half 

 of the eyebrow, and have received the name of depressor 

 supercilii. 



The CORRUGATOR SUPERCILII lies beneath the upper half 

 of the orbicularis palpebrarum, which must be dissected up 

 in order to expose it. It is usually confounded with the 

 orbicularis, and not always to be satisfactorily separated 

 from' it. It arises from the inner part of the superciliary 

 ridge, and is inserted into the under surface of the orbicu- 

 laris and frontalis muscles, being about an inch in length. 

 Upon the frontal bone, beneath the muscles last dissected, 

 will be found the divisions of the supra-orbital nerve, a 

 branch of the fifth cranial pair; these emerge from the 

 supra-orbital notch, and after supplying the muscles which 

 lie over it, are distributed to the epicranium and integu- 

 ment of the forehead. This nerve is accompanied by the 

 supra-orbital branch of the ophthalmic artery, a branch 

 of the internal carotid ; emerging at the supra-orbital fora- 

 men, it divides and is distributed like the nerve. 



The EYELIDS consist of two cartilages, one for the upper 

 and one for the lower lid, that of the upper being the 

 largest ; they are covered externally by muscles and integu- 

 ment, and along their free border the eyelashes are inserted ; 

 both are semi-lunar in shape, and attached to the edge of 

 the orbit by a membrane called the ligamentum palpebrse. 

 A small fibrous band, called the tendo oculi, arising from the 

 anterior margin of the lachrymal canal and dividing into 

 processes, one for each cartilage, fixes them internally ; a 

 fibrous band also attaches them to the margin of the orbit 

 externally. They are invested internally by a mucous mem- 

 brane called the conjunctiva ; this is continuous with that 

 covering the eyeball, from which it is reflected, and on both 

 surfaces is movable and vascular ; over the cornea it is thin 

 and transparent, and in the state of health no vessels are 

 traceable in that part. On the ocular surface of the carti- 

 lages may be seen numerous parallel and somewhat tortu- 

 ous lines, indicating the Meibomian glands, which open 

 along the free edges of the eyelids. The lachrymal canal 



2* 



