128 SPECIAL ANATOMY. 



external (red) layer upon the borders of the orbits covers corrugator 

 super cil. parts of frontalis, temporal., zygomalicus and levator 

 labii alseq. nasi. Origin: the internal angle of the eyes, lig. 

 paJpebrale internum. Insertion : the same, only rather farther 

 towards the nose. The internal layers of the superior and the 

 inferior eyelids are separated from one another. Action : the in- 

 ternal layer closes the eye and presses tin* bulb a little backwards. 

 The external shortens at the same time the fissure between the 

 lids, and corrugates the skin at the internal angle. Horner's 

 muscles merely draw the puncta lacrymalia deeper inwards; they 

 may also compress the lacrymal sacs. 



Nerves : palpebraks from supra-, infra-orbital. : and trochlear., lacrymal., sub- 

 cuian. mal., rr. temporal, n. facialis. 



156. 2. Corrugator supercilii. 



Figure: arched, narrow, flat. Position: upon the arcus super- 

 ciliaris, covered by frontalis and sphinct. palpebr. Origin: the 

 root of the nose. Insertion : to the superciliary arch as far as the 

 temple. Action : draws the brow inwards and downwards, there- 

 by corrugating the skin over the root of the nose lengthwise. 



Nerves: as frontalis. 



157. 3. Levator palpebrx superioris. 



Figure : long, flat, and narrow. Position : between the roof of 

 the orbits and the reclus bulbi sup.; above it, passes n. frontalis 

 (trigem.). Origin: close above the optic foramen from ala parva 

 of the sphenoid bone and sheath of nerv. opticus. Insertion : 

 with a broad aponeurosis to the superior border of the tarsus. 

 Action : draws back the superior lid upwards, particularly on ele- 

 vation of the globe. 



Nerves: oculo-motorius. 



D. Muscles of the Nose. 



158. 1. Depressor al& nasi. 



Position: close upon the upper jaw, covered by sphinct. oris 

 and fevat. labii alseq. nasi. Origin: before the roots of the two 

 incisor and the canine teeth. Insertion: the posterior part of the 

 septum mobile and the a/as nasi. Action: draws the inferior 

 part of the nose downwards and backwards (sulcus naso-fabialis 

 becomes deeper.) Fibres from it penetrate the upper lip ; these 

 are m. Incisivus (Cowperi) superior. 



