MUSCLES OF THE EYELIDS AND NOSE. 173 



auricular ; 3, corrugator supercilii ; 4, malar portion of the orbicularis palpebrarura ; 4', 

 palpebral portion ; below i, the expanded insertion of levator palpebrre superioris in the 

 eyelid ; 5, pyramidalis nasi ; 6, insertion of the triangulares nasi on the dorsum of the 

 nose ; 7, levator labii superioris alaeque nasi ; 8, orbicularis oris of the left side ; 8', 

 outer part of the same on the right side, the inner part being removed ; 9, levator labii 

 superioris; -f, zygomaticus minor; 10, zygomaticus major; 11, depressor anguli oris; 

 12, depressor labii inferioris ; d, points to the cut ends of the levatores menti ; 13, placed 

 on the left masseter, points to the buccinator ; 13', buccinator, of the right side, a 

 portion of the parotid duct passing through the muscle ; 14, levator anguli oris, seen 

 also on the left side behind the zygomaticus minor. The remaining references which 

 apply to the muscles of the neck will be found described at page 194. 



horizontally outwards to the inner commissure of the eyelids, where it 

 divides into two thin fibrous lamellae, which diverge as they pass outwards 

 in the substance of the eyelids, and terminate in the tarsal cartilages. 

 One surface of the tendon is subcutaneous ; the other crosses the lachrymal 

 sac a little above the centre, and from it a thin but firm fascia is given off, 

 which spreads over the lachrymal sac, and adheres to the margins of the 

 groove which lodges it. 



The tensor tarsi Horner, (musculus sacci lachrymalis,) consists of very 

 thin fibres resting on the fascia just mentioned. It is only a deep portion 

 of the insertion of the marginal fibres of the ciliary part of the orbicularis 

 muscle : two slips, one from each eyelid, passing behind the lachrymal 

 canals, unite on the surface of the lachrymal sac before reaching their attach- 

 ment on the posterior part of the lachrymal bone. 



The corrugator supercilii is a small muscle narrower below than above, 

 placed at the inner side of the eyebrow. It arises from the inner extremity 

 of the superciliary ridge of the frontal bone ; thence its fibres proceed 

 outwards and a little upwards, and end, at the middle of the orbital arch, 

 by becoming blended with those of the orbicularis and occipito-frontalis 

 muscles, by which it is concealed. 



This muscle crosses the supratrochlear branch of the ophthalmic nerve and the 

 accompanying artery as they emerge from the orbit. 



The levator palpebrce superioris is a muscle occupying the upper part of the 

 orbit, but the insertion of which is seen in the dissection of the upper eyelid, 

 in which it forms a broad fibrous expansion which curves downwards 

 towards its margin, and is inserted under cover of the orbicularis muscle 

 into the forepart of the tarsal cartilage. It will be described along with 

 the muscles of the orbit. 



ACTIONS. The orbicularis palpebrarum closes the eyelids. In the ordinary closure 

 of the eye, it is chiefly the upper lid which moves, being depressed by the superior half 

 of the ciliary part of the muscle ; but in forcible closure both eyelids move, and not 

 only come together, but are drawn towards the nose at the same time that the eyebrows 

 are drawn downwards and inwards, the whole fibres of the orbicularis being thus 

 contracted and approached towards the tendo palpebrarum. In those circumstances 

 the fibres which form the tensor tarsi, being contracted like the others, compress the 

 lachrymal sac, and prevent the introduction into it of the lachrymal secretion from 

 the conjunctiva. The corrugator muscles draw the skin of the forehead downwards 

 and inwards, raising longitudinal furrows, as in frowning. The upper eyelid is 

 supported by the levator palpebrse, and droops when that muscle is paralysed. On 

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

 eyelids. 



MUSCLES OF 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 

 levator labii superioris alaeque nasi whose action is common to the nose and lip. 



