FACE. 



221 



lures, is also furnished with its contractor or 

 sphincter muscle, and with many dilators 

 which radiate from it at various angles. 



All the muscles of the face are superficially 

 situated, and most of them are subcutaneous. 



In the palpebral regions, or about the eye- 

 lids on each side, are placed, 1. a constrictor, 

 or the orbiculuris palpebrarum, of which the 

 corrugutor snpcrcilii is an associate; 2. the 

 levator pnlpebra and the vccipil&J'rimtalit, 

 which are dilators, and antagonists of the two 

 former muscles. 



The orbiculiiris palpebrurum,(naso-palpebral, 

 Chauss.) is a flat oval muscle, situated im- 

 mediately underneath the skin, to which it 

 adheres, and covering the base of the orbit 

 and the superficial surface of the eyelids ; in 

 the middle it presents a transverse aperture, 

 which is the orifice of the palpebne, varying 

 in size according to the individual, and giving 

 apparently a greater or less magnitude to the 

 globe itself, which, however, is of nearly uni- 

 form dimensions in different persons. The 

 orbicularis, like the other sphincter muscles, 

 consists of concentric fibres, but it is peculiar 

 in having a fixed tendon on one side, from 

 which a great part of the fibres arise; this 

 tendon of the orbicularis, or ligamentum pal- 

 pebnc, which is situated horizontally at the 

 inner corner of the eye, is about two and a 

 half lines in length, and half a line in breadth; 

 it arise; from the anterior border of the lachry- 

 mal groove in the nasal process of the upper 

 maxillary bone, and passing horizontally out- 

 wards in front of the lachrymal sac, divides 

 into a superior and an inferior slip, which are 

 attached to the inner extremities of the corres- 

 ponding eyelids. The tendon at first is flat- 

 tened anteriorly and posteriorly, but afterwards 

 becomes twisted so as to present horizontal 

 surfaces. From its posterior part is detached 

 a slip of fibres (the reflected tendon of the 

 orbicularis), which proceeds backwards to- 

 wards the os unguis, and forms the outer wall 

 of the lachrymal canal. 



The orbiculuris arises, 1. from the borders 

 and surfaces of this tendon and from its 

 reflected slip; 2. from the internal angular 

 process of the frontal bone and from the fronto- 

 maxillary suture ; 3. from the nasal process of 

 the upper maxillary bone ; and, 4. by short 

 tendinous slips from the inner third of the lower 

 border of the orbit. From these origins the 

 upper and lower fibres of the muscle take a 

 curved direction outwards, their concavity look- 

 ing towards the aperture of the lids, and fol- 

 lowing the course of the upper and lower 

 borders of the orbit, which they overlap. 

 They unite at the outer side ; not, however, by 

 a tendinous raphe or septum, as some have 

 described, but simply by the mingling of their 

 fibres. Each half (the upper and lower) of 

 the orbicularis consists really of two sets of 

 fibres ; one, which covers the margins of the 

 orbits, and forms the circumference of the 

 muscles, is strong, tense, and of the usual 

 reddish colour ; it arises from the direct ten- 

 don, and from the frontal or upper maxillary 

 bone. These form tlie orbicularis properly so 



called. The other set, which is pale and thin, 

 covers the lids and proceeds almost in a hori- 

 zontal direction outwards from the palpebral 

 bifurcation of the orbicular tendon : this forms 

 the ciliary or palpebrales. These two sets of 

 fibres, as we shall presently see, are distin- 

 guished as much by their functions as by their 

 appearance. 



Relations. The superficial surface of that 

 part of the muscle which covers the lids 

 (the palpebrales) is connected to the skin by 

 delicate loose cellular tissue entirely destitute 

 of fat. The stronger fibres which form the 

 outer part of the muscles are closely adherent 

 to the integument by cellular tissue more 

 densely woven, and presenting more or less 

 fat. fhe posterior surface covers, above, the 

 lower part of the frontalis and the corrugator 

 supercilii, with whose fibres it is connected ; 

 internally the corresponding part of the fibro- 

 cartilages of the lids, the lachrymal sac, and 

 the inner border of the orbit externally, the 

 outer border of the orbit and part of the tem- 

 poral fascia inferiorly, the upper part of the 

 malar bone, the origins of the levator labii 

 superioris proprius, the part of the levator 

 labii superioris alxque nasi, and the inferior 

 border of the orbit. At its circumference this 

 muscle corresponds, by its upper half, to the 

 frontal, which it slightly overlaps, and inter- 

 nally to the border of the pyramidalis, with 

 which it is connected; externally it is free. 

 Below its border is free, covering the origin, 

 and giving some fibres to the lesser zygoraatic ; 

 and internally it is separated from the levator 

 labii superioris alteque nasi by cellular tissue, 

 in which runs the facial vein. The central 

 fibres cover the palpebral fascia and the lids, 

 which separate them from the conjunctiva. 



Action. The action of this muscle resem- 

 bles that of other sphincters, the curved fibres 

 in contraction approaching the centre ; but as 

 in the orbicularis palpebrarum these fibres are 

 fixed at the inner side, it follows that the skin 

 to which the muscle is attached by its anterior 

 surface is drawn towards the nose, and when 

 the muscle is in strong action, becomes cor- 

 rugated, presenting folds which converge to- 

 wards the inner angle of the eye; above, where 

 the effect of the muscle on the skin is most 

 marked in consequence of its closer connec- 

 tion with the integuments, the brow and the 

 skin of the forehead are drawn down by it 

 and its associate the corrugator; the lower 

 fibres when in strong action, draw the cheeks 

 upwards and inwards. Like the other sphinc- 

 ters, also, this is a mixed muscle. Those 

 fibres which may be supposed to be voluntary, 

 are the larger and outer ones, which corres- 

 pond to the border of the orbit, and are of a 

 red colour. The iuvoluntary fibres are those 

 thin ones which cover the lids, are of a pale 

 colour, like the muscles of organic life, and 

 arise from the palpebral subdivisions of the 

 horizontal tendon. They contract involuntarily 

 while we are awake, in the action of winking, 

 and during sleep in maintaining the lids closed ; 

 they also act under the will in closing the 

 lids, particularly the upper. It appears then 



