MUSCLES OF THE EYELIDS. 267 



11, triangularis oris or depressor anguli oris ; 12, levator menti ; 13, on the masseter 

 is immediately above the risorius or upper horizontal fibres of the platysma myoides, 

 and a line from it points to the buccinator ; 14, platysma myoides ; 15, on the upper 

 j)art of the sterno-mastoid, points by a line to the posterior belly of the digastric 

 muscle ; 15', the sternal tendon of the sterno-mastoid, a part of its clavicidar jjortion 

 is seen near c : 16, trapezius ; 17, splenius capitis ; +, splenius colli ; 18, levator scapulte • 

 19, sterno-hyoid ; 20, omo-hyoid ; 21, pectoralis major, its pectoral part ; 21' its 

 clavicular part ; 22, deltoid. 



fibres form neaiy concentre curves, and are attached by their extremities 

 at the inner angle of the orbit ; 1st, to the edges and anterior smface of 

 the tendo palpebrarum ; 2nd, to the srfoce of the nasal process of the 

 superior maxilla, near the anterior margin of the lachrymal groove ; 

 and 3rd, to the internal angular process of the frontal bone. 



nHntions. — The palpchral portion of the muscle consists of thin, pae^ and 

 slightly curved fibres situated in the eyelids, and ■K-hich conceal the tarsal carti- 

 lages and the insertion of the levator palpebrre superioris ; the vrh'hntlar portion, 

 more largely developed, rests on the cheek and margin of the orbit. Superiorly 

 this muscle conceals the corrugator supercCii, with which and the occipito- 

 frontalis it is intimately connected ; interiorly it covers the origin of the 

 elevators of the upper lip. part of the common elevator of the lip and nose, and 

 the lachl•3^nal sac ; and externally it lies upon a part of the temporal fascia. 



The tendon of the orbicularis muscle (tendo palpebrarum), at the 

 inner commissure of the eyelids, is a small white cord which is often ob- 

 scured by the filires of the muscle, but is rendered apparent by drawing 

 the lids outwards. This tendon is about two lines in length, and half 

 a line in breadth, and is attached to the anterior margin of the lach- 

 rymal groove ; thence it runs horizontally outwards to the inner com- 

 missure of the eyelids, where it divides into two thin fibrous lamellse, 

 which d'verge, and terminate on the tarsal cartilages. One surface of 

 the tendon is subcutaneous ; tl^.e 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 lodger it. 



The tensor tarsi — (musculus sacci lachrymalis, Horner) — consists 

 of very thin fibres resting on the fascia just mentioned. It is only a 

 deep portion of the inner marginal fibres of the ciliary part of the 

 orbicularis muscle : two s'lips, one from each eyelid, passing behind the 

 lachrymal canals, unite on the hinder surface of the lachrymal sac before 

 reaching their attachment on the posterior margin of the lachrymal 

 g cove. 



The corrugator supercilii is a small, deeply-coloured muscle, 

 narrower beloAV 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. 



delations. — This muscle crosses the supratrochlear branch of the ophthalmic 

 nerve and the accompanying vessels, as they emerge from the orbit. It rests 

 u]ion the frontal bone and is covered by the orbicularis and occipito-frontalis 

 muscles. 



The levator palpebrae superioris occupies the upper part of the orbit. 

 Its tendon only is seen in the dissection of the upper eyelid, in which it 

 forms a broad fibrous expansion which curves downwards, and is 



