THE MUSCLES OF THE KOSE. 283 



One surface of the ligament is subcutaneous ; the other crosses the lachrymal sac, to 

 which it is closely adherent, a little above the centre, and from it a process is given 

 off, which passes on the posterior side of the sac to be attached to the crest on the 

 lachrymal bone. The external tarsal ligament is a much weaker structure connect- 

 ing the eyelids to the malar bone. 



The tensor tarsi (muse, sacci lachrymalis, Horner) is regarded by many 

 anatomists as only a deep origin of the palpebral part of the orbicularis muscle. 

 It consists of a thin layer of fibres, which springs from the lachrymal crest 

 behind the sac and, passing outwards and forwards, divides into_two slips 

 which are continued behind the lachrymal canals into the ciliary bundles of the 

 orbicularis. 



The corrugator supercilii is a small, deeply-coloured muscle, placed at the 

 inner side of the eyebrow, under cover of the orbicularis and frontalis muscles. It 

 arises from the inner extremity of the superciliary ridge of the frontal bone ; 

 thence its fibres proceed outwards and upwards, diverging somewhat, and end 

 about the middle of the orbital arch, by passing between the bundles of the orbi- 

 cularis and frontalis, and becoming inserted into the deep surface of the skin of the 

 eyebrow. 



Relations. This muscle rests upon the frontal bone, and it crosses the supratrochlear 

 branch of the ophthalmic nerve and the accompanying- vessels, as they emerge from the orbit. 



The levator palpebrse superioris lies in the upper part of the orbit. Its 

 tendon only is seen in the dissection of the upper eyelid, where it forms a broad 

 expansion which curves downwards, and ends under cover of the orbicularis muscle 

 and palpebral ligament by becoming blended with the fibrous tarsus. It will be 

 fully described along with the muscles of the orbit (p. 289)." 



Actions. The palpebral part of the orbicular-!* closes the eyelids, the upper lid ordinarily 

 moving much more freely than the lower. The upper half of the orbital part depresses the 

 eyebrow, and stretches the skin of the forehead, opposing the frontalis muscle ; the lower half 

 of this part raises the skin of the cheek, and gives rise to wrinkles below and outside the eye. 

 The whole muscle comes into play in forcible closure of the eye, the orbital part then drawing 

 up the surrounding skin and pressing the lids firmly together, while they at the same time 

 are carried somewhat inwards towards the fixed part of the muscle. In closing the lids, as in 

 winking, the contraction of the palpebral part of the orbicularis carries forwards the internal 

 tarsal ligament and anterior wall of the lachrymal sac, which is thus dilated and sucks in the 

 tears. The tanner tarsi muscle, according to one view, contracts simultaneously with the 

 orbicularis, and draws backwards the puncta lachrymalia, disposing them more favourably for 

 the admission of the tears ; but it appears more probable that the tensor alternates in its 

 action with the orbicularis, and that, by drawing backwards the tarsal ligament, it compresses 

 the sac, and so propels the tears along the nasal duct into the nose. The corrucjator muscle 

 draws the skin of the outer part of the forehead downwards and inwards, producing 

 longitudinal furrows at the inner end of the eyebrow, as in frowning. The upper eyelid is 

 supported by the Icrator palpe'brw , and droops when that muscle is paralysed. On the other 

 hand, paralysis of the orbicularis is attended by an inability to close the eyelids. 



THE MUSCLES OP THE NOSE. 



Under this head may be conveniently grouped not only the compressor 

 naris and smaller muscles which act upon the nose alone, but also the pyramidalis 

 nasi which acts on the forehead and the common elevator of the lip and wing of the 

 nose. 



The pyramidalis nasi, placed over the nasal bone, appears to be a prolongation 

 of the inner part of the frontalis ; its fibres, however, decussate with' those of the 

 latter muscle, and are attached to the skin at the lower and mesial part of the fore- 

 head. It widens slightly as it descends, and terminates in a tendinous expansion 

 common to it and the compressor naris. 



