| Internal structure of the eyelids.—The tar- 
_ §al cartilages may be looked upon as the skele- 
on of the eyelids, and the membraneous ex- 
nsion intervening between them and the mar- 
fins of the orbits as connecting ligaments. The 
itter, indeed, are called the tarsal ligaments, 
_ although they do not in reality possess a liga- 
» Mentous structure, but consist merely of dense 
“laminar cellular membrane. On the inner sur- 
ice of the tarsal cartilages and tarsal ligaments 
le palpebral conjunctiva adheres. On the 
uter surface are the palpebral and ciliary por- 
ons of the orbicularis palpebrarum muscle, over 
lich is the skin. Moreover, incorporated 
th the superior tarsal ligament is the expan- 
in of the tendon of the levator palpebre supe- 
bris muscle. Imbedded in the substance of 
he tarsal cartilages lie the Meibomian follicles. 
nderneath the skin and the ciliary portion of 
ordicularis palpebrarum muscle, the roots of 
meyels shes lie close on the tarsal cartilages. 
Tarsal* cartilages —Tarsi; Fr., Les Tarses; 
41 tarsi; Germ., Der Augenliedknorpel. 
se are thin plates of fibro-cartilage, convex 
the outer surface, concave on the inner, to 
_ be adapted to the front of the eyeball. The 
pper is the larger. One of their margins is 
and straight, the other thin and curved, 
pecially so in the upper, which therefore re- 
nts in some degree a segment of a circle, 
ilst the lower is little more than a narrow 
- The thick and straight margin, called 
the ciliary, forms the margin of the eyelid; the 
hin and curved margin, called orbital, degene- 
es into the membraneous expansion already 
mentioned under the name of tarsal ligaments. 
rowards the outer canthus the orbital margins 
of the tarsal cartilages run into the ciliary ones 
tan acute angle, whilst towards the inner can- 
thus they form an obtuse angle by their junc- 
ion. The transverse length of the tarsal carti- 
lages is somewhere about an inch, the breadth 
of the upper cartilage at its broadest part about 
one-third of an inch, the breadth of the lower 
cartilage only half as much. At the inner can- 
thus the tarsal cartilages extend no farther than 
the lacrymal points, and at the outer canthus 
hey stop close to the commissure of the two 
: 
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if 
a 
Pe oe ee eae 
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As to the intimate composition of the tarsal 
Cartilages, they consist of what is called fibro- 
age, a microscopically fibrous substance, 
hout any of the corpuscles of common carti- 
a 
fee 
is substance is inconsiderable, and its con- 
istence not so great as in the upper. In the 
ower animals itis in the same state in both 
yelids. This is what has led Zeiss+ to say 
hat he never found a real cartilaginous tarsus 
in the human lower eyelid, nor among the lower 
mammifera in the upper eyelid either. “In 
‘In the human lower eyelid, the thickness of 
. 
__ * Tarsus, propter siccitatem quod carnis sit ex- 
togie. Bad. iv. p. 249, 
i VOL. ITI. 
i 
LACRYMAL ORGANS. 
81 
the sow only,” says he, “there isa nearer ap- 
proach to a tarsal cartilage than is to be found 
in apy other of the lower animals.” Miiller* 
has very well explained away all this difference 
of opinion, by showing that the dense cellular 
tissue which, according to Zeiss, occupies the 
place of tarsal cartilage in the human lower 
eyelid, and in both those of the inferior mammi- 
fera, is the same tissue, as the more consistent 
fibro-cartilage of the human upper eyelid, only 
in a less condensed state. 
The Meibomian glands are commonly de- 
scribed as being situate between the palpebral 
conjunctiva and tarsal cartilage. Winslow, 
Haller, and Zinn describe them as lying in 
grooves on the posterior surface of the tarsal 
cartilages. The Meibomian glands are seen 
very distinctly from the inside of the eyelids, as 
if they were immediately underneath the con- 
junctiva. But if the skin and orbicularis muscle 
be removed from the outside, these glands be- 
come equally viSible there.. “‘ Where, then,” 
asks Zeiss,t “do they lie,—before or behind 
the tarsal cartilage?” Examination of sections 
of the cartilage shows that the Meibomian glands 
lie in the substance of the tarsal cartilage itself ; 
and in the human lower eyelid and in both 
those of the lower animals, in the less consistent 
fibrous structure which there composes the 
tarsus. 
At the outer canthus the cellulo-membra- 
neous expansions called tarsal ligaments are 
stronger, and form bands which decussate and 
thus tie the tarsal cartilages to each other and 
to the outer margin of the orbit. These bands 
compose what is called the external palpebral 
ligament. 
The internal palpebral ligament is the tendon 
of the orbicularis palpebrarum muscle,—tendo 
oculi, or tendo palpebrarum. This, to adopt 
the description of Professor Harrison of Dub- 
lin, “is a small horizontal tendon, nearly one 
quarter of an inch in length. It is inserted in- 
ternally into the upper end of the nasal process 
of the superior maxillary bone ; thence it passes 
outwards and backwards to the internal com- 
missure of the eyelids, where it forks into two 
slips which enclose the caruncula lacrymalis, 
and are then inserted each into the tarsal carti- 
lage and the lacrymal duct.’’f 
Orbicularis palpebrarum muscle.—This is de- 
scribed in the article Face, vol.ii. p. 221. Here 
we shall only advert to some particular. points 
in its history. The fibres of the. orbicularis 
pertaining to the upper eyelid arise from the 
Internal angular process of the frontal bone, and 
from the upper edge of the tendo palpebrarum, 
and proceed, forming a curve, at first upwards 
and outwards, and then downwards and out- 
wards, within the upper eyelid and along and 
over the upper edge of the orbit towards the 
temple and outer angle of the eye. Here they 
meet those of the lower eyelid which have come 
from the nasal process of the upper jaw-bone, 
* Archiv, 1836. Jahresbericht, p. xxxviii. 
t L.c. p. 240, and op. cit. Bd. v. S. 216. See 
also Sichel in Lancette Franeaise, Gazette des Ho-~ 
pitaux, No. 53, 55, and 57. Paris, 1833, 
$ Dublin Dissector, 4th ed. p. 6. 
G 
